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manet-thesis-99mar - 1998:362 MASTER'S THESIS Routing. Click to edit the document details. Unformatted text preview: 1998:362 MASTER'S THESIS Routing Protocols in Wireless Ad-hoc Networks A Simulation Study Tony Larsson, Nicklas Hedman Civilingenjorsprogrammet 1998:362 • ISSN: 1402-1617 • ISRN: LTU-EX--98/362--SE Master’s thesis in Computer Science and Engineering Routing Protocols in essay, Wireless Ad-hoc Networks A Simulation Study Stockholm, 1998 Tony Larsson and cause violence essay Nicklas Hedman Lulea University of value essay, Technology Supervisor: Per Johansson Switchlab Ericsson Telecom AB Examiner: Mikael Degermark Department of Computer Science and Electrical Engineering Division of Computer Communications, Lulea University of Technology Abstract Ad-hoc networking is and contrast texting essay, a concept in computer communications, which means that users wanting to communicate with each other form a temporary network, without any form of centralized administration. Each node participating in the network acts both as host and a router and must therefore be willing to forward packets for value education other nodes. For this purpose, a routing protocol is needed. An ad-hoc network has certain characteristics, which imposes new demands on the routing protocol. The most important characteristic is the dynamic topology, which is a consequence of node mobility. Nodes can change position quite frequently, which means that we need a routing protocol that quickly adapts to topology changes. The nodes in an ad-hoc network can consist of laptops and personal digital assistants and are often very limited in resources such as CPU capacity, storage capacity, battery power and bandwidth.
This means that the routing protocol should try to minimize control traffic, such as periodic update messages. Instead the thesis routing protocol should be reactive, thus only calculate routes upon receiving a specific request. The Internet Engineering Task Force currently has a working group named Mobile Ad-hoc Networks that is working on value education routing specifications for ad-hoc networks. This master thesis evaluates some of the protocols put forth by the working group. This evaluation is done by means of simulation using Network simulator 2 from cause and effect of domestic violence essay Berkeley.
The simulations have shown that there certainly is a need for a special ad-hoc routing protocol when mobility increases. More conventional routing protocols like DSDV have a dramatic decrease in performance when mobility is high. Two of the proposed protocols are DSR and essay AODV. They perform very well when mobility is high. And Contrast Essay? However, we have found that a routing protocol that entirely depends on messages at the IP-level will not perform well. Value Essay India? Some sort of support from the ap lang analysis essay prompt lower layer, for instance link failure detection or neighbor discovery is necessary for value education essay high performance. The size of the network and the offered traffic load affects protocols based on source routing, like DSR, to some extent. A large network with many mobile nodes and high offered load will increase the overhead for DSR quite drastically.
In these situations, a hop-by-hop based routing protocol like AODV is more desirable. Preface This report is the result of our master thesis project carried out at Ericsson Telecom, Switchlab in Stockholm. This master thesis is of domestic violence, also the last part of our Master of value education essay india, Science degree at illegal for research paper, Lulea University of Technology. Switchlab is an applied research organization within Ericsson, working on network studies and technologies for products in the foreseeable future. This master thesis project has been a cooperation between Switchlab in Stockholm and essay india Ericsson Mobile Data Design (ERV) in practice world, Gothenburg.
Our master thesis consisted of value essay, conducting a simulation study of proposed routing protocols in ad-hoc networks. The thesis work done at ERV implemented one of the ap lang analysis essay proposed routing protocols and tested it in a simple scenario. This has made it possible to india, share thoughts and ideas with each other. We would like to thank the following persons: Per Johansson for being our supervisor at illegal immigration, Switchlab, Bartosz Mielczarek for contribution of the realistic scenarios and essay Mikael Degermark for being our Examiner at Lulea University of Technology. Also thanks to Johan Kopman and Jerry Svedlund in Gothenburg for discussions and comments regarding AODV. Finally, we would also like to and effect of domestic essay, thank Mats Westin and Henrik Eriksson for giving us feedback on this report. Value India? Table of Contents 1 INTRODUCTION . 9 1.1 1.2 1.3 1.4 1.5 1.6 2 BACKGROUND . 9 PROBLEM DESCRIPTION . 9 RELATED WORK . 10 PROJECT ORGANIZATION . 10 DISPOSITION . 11 ABBREVIATIONS . 11 GENERAL CONCEPTS.
12 2.1 WIRELESS AD-HOC NETWORKS . 12 2.1.1 General. 12 2.1.2 Usage. 13 2.1.3 Characteristics . 13 2.2 ROUTING . 14 2.2.1 Conventional protocols . 14 2.2.2 Link State. 14 2.2.3 Distance Vector . 14 2.2.4 Source Routing . 14 2.2.5 Flooding . Compare And Contrast Vs. Calling? 15 2.2.6 Classification. Essay? 15 3 AD-HOC ROUTING PROTOCOLS. 16 3.1 DESIRABLE PROPERTIES . 16 3.2 MANET. 17 3.3 DESTINATION SEQUENCED DISTANCE VECTOR - DSDV . 17 3.3.1 Description . 17 3.3.2 Properties . 17 3.4 AD-HOC ON DEMAND DISTANCE VECTOR - AODV . 18 3.4.1 Description . 18 3.4.2 Properties . 19 3.5 DYNAMIC SOURCE ROUTING - DSR.
20 3.5.1 Description . 20 3.5.2 Properties . 20 3.6 ZONE ROUTING PROTOCOL - ZRP . 21 3.6.1 Description . 21 3.6.2 Properties . 22 3.7 TEMPORALLY-ORDERED ROUTING ALGORITHM - TORA . 22 3.7.1 Description . 22 3.7.2 Properties . 23 3.8 INTERNET MANET ENCAPSULATION PROTOCOL - IMEP. 24 3.8.1 Description . 24 3.8.2 Properties . 24 3.9 CLUSTER BASED ROUTING PROTOCOL - CBRP. 24 3.9.1 Description . 24 3.9.2 Properties . Language Introduction? 26 3.10 COMPARISON. 26 4 SIMULATION ENVIRONMENT . 28 4.1 NETWORK SIMULATOR. 28 4.2 MOBILITY EXTENSION . 29 4.2.1 Shared media. 30 4.2.2 Mobile node. 30 4.3 SIMULATION OVERVIEW . 31 4.4 MODIFICATIONS . Value Essay India? 32 4.4.1 AODV . 32 4.4.2 DSR. 33 4.4.3 DSDV. 34 4.4.4 Flooding . World? 34 4.4.5 The simulator.
34 5 SIMULATION STUDY . 35 5.1 MEASUREMENTS . 35 5.1.1 Quantitative metrics . Value Education India? 35 5.1.2 Parameters . Immigration For Research Paper? 35 5.1.3 Mobility . 35 5.2 SIMULATION SETUP . 38 5.3 MOBILITY SIMULATIONS . Value? 39 5.3.1 Setup . 39 5.3.2 Fraction of received packets. And Contrast Vs. Calling Essay? 40 5.3.3 End-to-end delay . 41 5.3.4 End-to-end throughput . 42 5.3.5 Overhead . 43 5.3.6 Optimal path. 44 5.3.7 Summary mobility simulations. 46 5.4 OFFERED LOAD SIMULATIONS . 46 5.4.1 Setup . Essay India? 46 5.4.2 Fraction of received packets. 47 5.4.3 End-to-end delay . 48 5.4.4 End-to-end throughput . 49 5.4.5 Overhead . 49 5.4.6 Optimal path.
51 5.4.7 Summary offered load simulations . 51 5.5 NETWORK SIZE SIMULATIONS. 52 5.6 REALISTIC SCENARIOS . Outline? 52 5.6.1 Setup . 52 5.6.2 Conference. 53 5.6.3 Event coverage . 55 5.6.4 Disaster area . 57 5.6.5 Summary realistic scenarios. 60 5.7 OBSERVATIONS . 60 5.7.1 Ability to find routes . 60 5.7.2 Temporary backward routes. 61 5.7.3 Buffers . 62 5.8 DISCUSSION. 62 5.9 CLASSIFICATION. 62 5.9.1 Mobile networks . 63 5.9.2 Size of networks . Education? 63 5.9.3 Network scenarios . Compare Texting Vs. Calling? 64 5.10 IMPROVEMENTS . 64 6 IMPLEMENTATION STUDY . Value Education Essay India? 65 DESIGN. 65 6.1.1 Main . 65 6.1.2 Event queue . 66 6.1.3 Route table. 66 6.1.4 Neighbors / senders . 66 6.1.5 Request buffer.
66 6.1.6 Message . Cause And Effect? 66 6.2 SETUP . Value Essay? 66 6.3 TESTING . 67 6.3.1 Correctness. 67 6.3.2 Performance . 67 6.4 6.5 6.6 7 CONCLUSIONS. Illegal Outline Paper? 69 7.1 7.2 8 PROBLEMS / LIMITATIONS . 67 IMPROVEMENTS . 68 IMPLEMENTATION CONCLUSIONS . 68 RESULTS. 69 FURTHER STUDIES . Value Education Essay India? 69 REFERENCES . 71 APPENDIX A - TERMINOLOGY. And Contrast Texting Essay? 73 A.1 A.2 GENERAL TERMS . 73 AD-HOC RELATED TERMS . Value Essay India? 74 APPENDIX B - AODV IMPLEMENTATION FOR NS. 75 B.1 MESSAGE FORMATS. And Effect Of Domestic Essay? 75 B.1.1 Route Request – RREQ. 75 B.1.2 Route Reply - RREP. 76 B.1.3 Hello . Value Essay India? 76 B.1.4 Link failure . Violence? 76 B.2 DESIGN . Value Education Essay? 77 B.3 IMPORTANT ROUTINES.
78 B.3.1 Sending RREQ. Ap Lang? 78 B.3.2 Receiving RREQ . 78 B.3.3 Forwarding RREQ. 79 B.3.4 Forwarding RREP . 79 B.3.5 Receiving RREP . Education Essay India? 79 B.3.6 Hello handling . 80 B.3.7 Forwarding packets. Illegal Paper? 80 B.3.8 Sending Triggered RREP . 80 B.3.9 Receiving Triggered RREP. Education Essay? 80 APPENDIX C - SIMULATOR SCREENSHOTS . Immigration Outline For Research Paper? 81 C.1 C.2 NETWORK ANIMATOR . 81 AD-HOCKEY . 82 List of Figures Figure 1: Figure 2: Figure 3: Figure 4: Figure 5: Figure 6: Figure 7: Figure 8: Figure 9: Figure 10: Figure 11: Figure 12: Figure 13: Figure 14: Figure 15: Figure 16: Figure 17: Figure 18: Figure 19: Figure 20: Figure 21: Figure 22: Figure 23: Figure 24: Figure 25: Figure 26: Figure 27: Figure 28: Figure 29: Figure 30: Figure 31: Figure 32: Figure 33: Figure 34: Figure 35: Example of a simple ad-hoc network with three participating nodes. . 12 Block diagram of a mobile node acting both as hosts and as router. . Value Essay India? 13 Network using ZRP. The dashed squares show the routing zones for nodes S and practice dbq ap D. 22 Directed acyclic graph rooted at destination. 23 IMEP in the protocol stack. . 24 Bi-directional linked clusters. 25 Network simulator 2. . 28 Shared media model. Education? . 30 A mobile node. . 31 Simulation overview. 32 Example of mobility. . Compare And Contrast Vs. Calling? 37 Relation between the value education india number of link changes and mobility. . 37 Mobility simulations - fraction of received packets. . 40 Mobility simulations - delay. 41 Mobility simulations - throughput. . 42 Mobility simulations - overhead.
43 Mobility simulations - optimal path difference. . Memoir Class Thesis? 45 Offered load simulations - fraction of received packets. . 47 Offered load simulations - average delay. . 48 Offered load simulations - average throughput. . 49 Offered load simulations - overhead. 50 Offered load simulations – optimal path. 51 Conference scenario. . 54 Event coverage scenario. . 56 Disaster area scenario. . 58 Simple example scenario. . 60 Overview of AODV daemon. Value Education Essay? . 65 Different router identification approaches. From left to right: 3a, 3b, 3c. 70 Route request format. . 75 Route reply format. 76 AODV design of and contrast texting vs. calling, implementation for simulator. India? . 77 Screenshot – Network animator. 81 Screenshot – Ad-hockey – Conference scenario. Class? . Education Essay? 82 Screenshot – Ad-hockey – Event coverage scenario. . 83 Screenshot – Ad-hockey – Disaster area. . 83 List of Tables Table 1: Table 2: Table 3: Table 4: Table 5: Table 6: Table 7: Table 8: Table 9: Table 10: Table 11: Table 12: Table 13: Table 14: Table 15: Table 16: Table 17: Table 18: Table 19: Table 20: Table 21: Neighbor table. . Practice World History? 25 Comparison between ad-hoc routing protocols. . Education Essay? 27 Constants used in world history essay, the AODV implementation. 33 Constants used in the DSR implementation. . 33 Constants used in the DSDV implementation. . 34 Mobility variables. Education Essay? 36 Parameters used during mobility simulations. 39 Optimal path difference for all protocols. 45 Parameters used during offered load simulations. Memoir Class? . 47 Parameters used during realistic simulations.
53 Parameters used during conference scenario. . 53 Conference simulation results. . 54 Packet drops in conference scenario. 55 Parameters used during event coverage scenario. . 55 Event coverage simulation results. . 57 Packet drops in event coverage scenario. . 57 Parameters used during disaster area scenario. 57 Disaster area simulation results. . 59 Packet drops in disaster area. 59 Routing tables for AODV after a route discovery process. . 60 Routing caches for value education essay india DSR, after a route discovery process. 61 1 Introduction 1.1 Background Wireless communication between mobile users is becoming more popular than ever before. This due to recent technological advances in and contrast texting vs. calling essay, laptop computers and wireless data communication devices, such as wireless modems and wireless LANs. This has lead to lower prices and higher data rates, which are the two main reasons why mobile computing continues to enjoy rapid growth.
There are two distinct approaches for enabling wireless communication between two hosts. The first approach is to let the existing cellular network infrastructure carry data as well as voice. The major problems include the value problem of handoff, which tries to handle the situation when a connection should be smoothly handed over from one base station to another base station without noticeable delay or packet loss. Another problem is that networks based on the cellular infrastructure are limited to places where there exists such a cellular network infrastructure. The second approach is to form an ad-hoc network among all users wanting to compare vs. calling essay, communicate with each other. Education India? This means that all users participating in the ad-hoc network must be willing to forward data packets to make sure that the packets are delivered from memoir thesis source to education, destination. This form of networking is limited in range by history, the individual nodes transmission ranges and is typically smaller compared to the range of cellular systems. This does not mean that the cellular approach is better than the ad-hoc approach. Ad-hoc networks have several advantages compared to traditional cellular systems. These advantages include: N N N On demand setup Fault tolerance Unconstrained connectivity Ad-hoc networks do not rely on any pre-established infrastructure and can therefore be deployed in places with no infrastructure. This is useful in disaster recovery situations and places with non-existing or damaged communication infrastructure where rapid deployment of value education essay, a communication network is compare, needed.
Adhoc networks can also be useful on conferences where people participating in the conference can form a temporary network without engaging the services of any pre-existing network. Because nodes are forwarding packets for each other, some sort of routing protocol is necessary to education india, make the routing decisions. Currently there does not exist any standard for a routing protocol for ad-hoc networks, instead this is essay, work in progress. Many problems remain to be solved before any standard can be determined. This thesis looks at value education, some of these problems and language essay introduction tries to evaluate some of the currently proposed protocols. Value? 1.2 Problem description The objective for this master thesis was to evaluate proposed routing protocols for wireless ad-hoc networks based on performance.
This evaluation should be done theoretically and through simulation. It was also desirable to english essay introduction, compare the results with the results for routing protocols in value essay india, a traditional wired network. For Research Paper? At the essay beginning of this master thesis, no implementation of the protocols had been released, so the first main task was to memoir class, implement some of the protocols. The thesis also included the goal to generate a simulation environment that could be used as a platform for further studies within the area of ad-hoc networks. This simulation environment should if possible, be based on Network simulator 2 from Berkeley. 9 The goal of this master thesis was to: N N N N N N Get a general understanding of value essay india, ad-hoc networks. Generate a simulation environment that could be used for further studies. Texting? Implement some of the value india proposed routing protocols for ap lang prompt wireless ad-hoc networks.
Analyze the protocols theoretically and through simulation. Value Education? Produce a classification of the protocols with respect to applicability in compare and contrast texting vs. calling essay, combinations of small/large networks, and mobile/semi-mobile nodes. Recommend protocols for specific network scenarios. 1.3 Related work Many routing protocols have been proposed , but few comparisons between the different protocols have been made. Of the work that has been done in this field, only the work done by essay india, the Monarch1 project at Carnegie Mellon University (CMU) has compared some of the different proposed routing protocols and evaluated them based on english language introduction the same quantitative metrics. The result was presented in the article “A performance comparison of multi-hop ad hoc wireless network routing protocols”  that was released in the beginning of October 1998. There exist some other simulation results  that have been done on individual protocols. These simulations have however not used the same metrics and are therefore not comparable with each other. In parallel with our master thesis, a master thesis project in Gothenburg  implemented the india AODV  protocol and tested it in a environment that consisted of 5 computers with wireless interfaces. The cooperation between our projects and their project made it possible to cause and effect of domestic essay, share thoughts and ideas with each other. 1.4 Project organization The following persons have been involved in value essay india, this master thesis project: Simulation study and cause and effect essay master thesis authors M.Sc.
Tony Larsson M.Sc. Nicklas Hedman Supervisor at Ericsson Telecom AB, Switchlab Tekn.Lic. Per Johansson Examiner at Lulea University of essay, Technology Ph. D. Mikael Degermark Implementation study at Ericsson Mobile data design (ERV) in Gothenburg M.Sc. Johan Kopman M.Sc.
Jerry Svedlund Supervisor at ERV M.Sc. Christoffer Kanljung Contribution of realistic scenarios Ph.D. student at Chalmers University of Technology: Bartosz Mielczarek 1 MObile Networking ARCHitectures 10 1.5 Disposition This report consists of 8 chapters and two appendices. Chapters 1 and 2 explain the concept of ad-hoc networks and routing in general. Thesis? Chapter 3 describes the different routing protocols, analyzes and compares them. Chapters 4 and 5 describe the simulator and the simulations that were made. Chapter 6 describes the implementation study of AODV that was made in Gothenburg.
Chapter 7 concludes the whole report and chapter 8 is the essay references that we have used. Thesis? The appendices contain some terminology, details about the implementation of AODV that we did for the simulator and some screenshots of the simulator. 1.6 Abbreviations AODV CBR CBRP DSDV DSR IEEE IETF LAN IP MAC MANET OLSR PDA QoS TCP TORA UDP WINET ZRP Ad-hoc On-demand Distance Vector Constant Bit Rate Cluster Based Routing Protocol Destination Sequenced Distance Vector Dynamic Source Routing Institute of Electrical and Electronics Engineers Internet Engineering Task Force Local Area Network Internet Protocol Media Access Protocol Mobile Ad-hoc NETworks Optimized Link State Routing Protocol Personal Digital Assistant Quality of Service Transmission Control Protocol Temporally Ordered Routing Algorithm User Datagram Protocol Wireless InterNET Zone Routing Protocol 11 2 General Concepts 2.1 Wireless ad-hoc networks 2.1.1 General A wireless ad-hoc network is a collection of education essay india, mobile/semi-mobile nodes with no pre-established infrastructure, forming a temporary network. Each of the nodes has a wireless interface and communicate with each other over either radio or infrared. Laptop computers and personal digital assistants that communicate directly with each other are some examples of ap lang analysis prompt, nodes in an ad-hoc network.
Nodes in the adhoc network are often mobile, but can also consist of stationary nodes, such as access points to the Internet. Semi mobile nodes can be used to deploy relay points in areas where relay points might be needed temporarily. Figure 1 shows a simple ad-hoc network with three nodes. The outermost nodes are not within transmitter range of each other. However the middle node can be used to forward packets between the outermost nodes.
The middle node is acting as a router and value education india the three nodes have formed an ad-hoc network. Figure 1: Example of a simple ad-hoc network with three participating nodes. Illegal Outline For Research? An ad-hoc network uses no centralized administration. Essay India? This is to be sure that the network wont collapse just because one of the mobile nodes moves out of transmitter range of the others. Nodes should be able to enter/leave the analysis essay network as they wish. Because of the value education essay limited transmitter range of the nodes, multiple hops may be needed to reach other nodes.
Every node wishing to cause and effect of domestic violence essay, participate in an ad-hoc network must be willing to forward packets for other nodes. Thus every node acts both as a host and as a router. A node can be viewed as an abstract entity consisting of a router and value india a set of affiliated mobile hosts (Figure 2). A router is an entity, which, among other things runs a routing protocol. Illegal Immigration? A mobile host is simply an IP-addressable host/entity in the traditional sense. Ad-hoc networks are also capable of handling topology changes and malfunctions in nodes. It is education essay india, fixed through network reconfiguration. For instance, if a node leaves the texting essay network and causes link breakages, affected nodes can easily request new routes and the problem will be solved. This will slightly increase the delay, but the network will still be operational.
12 Wireless ad-hoc networks take advantage of the education india nature of the essay introduction wireless communication medium. In other words, in a wired network the value india physical cabling is practice dbq ap world, done a priori restricting the connection topology of the nodes. Value Essay India? This restriction is not present in the wireless domain and, provided that two nodes are within transmitter range of each other, an instantaneous link between them may form. Host Host Router Host Figure 2: Block diagram of a mobile node acting both as hosts and as router. 2.1.2 Usage There is no clear picture of what these kinds of practice history, networks will be used for.
The suggestions vary from document sharing at value india, conferences to infrastructure enhancements and military applications. In areas where no infrastructure such as the immigration for research Internet is available an education, ad-hoc network could be used by english language, a group of wireless mobile hosts. This can be the case in value, areas where a network infrastructure may be undesirable due to reasons such as cost or convenience. Thesis? Examples of such situations include disaster recovery personnel or military troops in cases where the education essay normal infrastructure is either unavailable or destroyed. Other examples include business associates wishing to share files in an airport terminal, or a class of students needing to interact during a lecture. If each mobile host wishing to essay, communicate is equipped with a wireless local area network interface, the group of essay, mobile hosts may form an ad-hoc network.
Access to and contrast texting essay, the Internet and access to resources in networks such as printers are features that probably also will be supported. 2.1.3 Characteristics Ad-hoc networks are often characterized by essay india, a dynamic topology due to the fact that nodes change their physical location by moving around. This favors routing protocols that dynamically discover routes over conventional routing algorithms like distant vector and link state . Another characteristic is that a host/node have very limited CPU capacity, storage capacity, battery power and english language bandwidth, also referred to as a “thin client”. This means that the power usage must be limited thus leading to a limited transmitter range. The access media, the radio environment, also has special characteristics that must be considered when designing protocols for education essay ad-hoc networks. Ap Lang Analysis Essay Prompt? One example of this may be unidirectional links. These links arise when for example two nodes have different strength on their transmitters, allowing only one of the host to hear the other, but can also arise from disturbances from the surroundings.
Multihop in value, a radio environment may result in an overall transmit capacity gain and cause of domestic essay power gain, due to the squared relation between coverage and required output power. By using multihop, nodes can transmit the packets with a much lower output power. 13 2.2 Routing Because of the fact that it may be necessary to education india, hop several hops (multi-hop) before a packet reaches the destination, a routing protocol is practice dbq ap world, needed. The routing protocol has two main functions, selection of routes for various source-destination pairs and the delivery of messages to their correct destination. The second function is conceptually straightforward using a variety of protocols and data structures (routing tables). This report is value education essay india, focused on selecting and finding routes. 2.2.1 Conventional protocols If a routing protocol is needed, why not use a conventional routing protocol like link state or distance vector? They are well tested and most computer communications people are familiar with them. The main problem with link-state and ap lang essay prompt distance vector is that they are designed for a static topology, which means that they would have problems to converge to education, a steady state in an ad-hoc network with a very frequently changing topology. Analysis Essay Prompt? Link state and distance vector would probably work very well in an ad-hoc network with low mobility, i.e. a network where the topology is not changing very often. The problem that still remains is that link-state and essay india distance-vector are highly dependent on periodic control messages.
As the number of network nodes can be large, the potential number of destinations is also large. This requires large and frequent exchange of data among the network nodes. This is in contradiction with the fact that all updates in and effect of domestic violence, a wireless interconnected ad hoc network are transmitted over the air and thus are costly in resources such as bandwidth, battery power and CPU. Because both link-state and distance vector tries to maintain routes to all reachable destinations, it is necessary to maintain these routes and this also wastes resources for value india the same reason as above. Another characteristic for conventional protocols are that they assume bi-directional links, e.g. that the transmission between two hosts works equally well in practice dbq ap world essay, both directions. In the wireless radio environment this is not always the case. Because many of the proposed ad-hoc routing protocols have a traditional routing protocol as underlying algorithm, it is necessary to understand the basic operation for conventional protocols like distance vector, link state and source routing. 2.2.2 Link State In link-state routing , each node maintains a view of the education essay india complete topology with a cost for each link. To keep these costs consistent; each node periodically broadcasts the link costs of its outgoing links to all other nodes using flooding. And Contrast Texting? As each node receives this information, it updates its view of the network and applies a shortest path algorithm to choose the next-hop for each destination. Some link costs in a node view can be incorrect because of long propagation delays, partitioned networks, etc.
Such inconsistent network topology views can lead to formation of education essay india, routing-loops. These loops are however short-lived, because they disappear in class, the time it takes a message to value education essay, traverse the diameter of the network. 2.2.3 Distance Vector In distance vector  each node only monitors the and contrast texting vs. calling cost of its outgoing links, but instead of value education, broadcasting this information to all nodes, it periodically broadcasts to each of its neighbors an estimate of the shortest distance to every other node in the network. The receiving nodes then use this information to recalculate the routing tables, by essay, using a shortest path algorithm. Compared to education, link-state, distance vector is more computation efficient, easier to implement and requires much less storage space. However, it is well known that distance vector can cause the formation of both short-lived and long-lived routing loops. The primary cause for this is that the nodes choose their next-hops in a completely distributed manner based on information that can be stale. 2.2.4 Source Routing Source routing  means that each packet must carry the complete path that the ap lang analysis essay prompt packet should take through the network. The routing decision is therefore made at essay, the source. The advantage with this approach is that it is very easy to avoid routing loops.
The disadvantage is that each packet requires a slight overhead. 14 2.2.5 Flooding Many routing protocols uses broadcast to ap lang essay prompt, distribute control information, that is, send the control information from an origin node to essay india, all other nodes. A widely used form of thesis, broadcasting is flooding  and value india operates as follows. The origin node sends its information to its neighbors (in the wireless case, this means all nodes that are within transmitter range). The neighbors relay it to their neighbors and so on, until the packet has reached all nodes in the network.
A node will only relay a packet once and to ensure this some sort of sequence number can be used. This sequence number is increased for each new packet a node sends. 2.2.6 Classification Routing protocols can be classified  into different categories depending on their properties. Of Domestic Violence Essay? N N N Centralized vs. Distributed Static vs.
Adaptive Reactive vs. Proactive One way to categorize the routing protocols is to divide them into centralized and distributed algorithms. In centralized algorithms, all route choices are made at a central node, while in distributed algorithms, the computation of routes is shared among the network nodes. Another classification of routing protocols relates to whether they change routes in response to the traffic input patterns. In static algorithms, the route used by source-destination pairs is fixed regardless of value education india, traffic conditions. It can only change in memoir, response to a node or link failure. This type of algorithm cannot achieve high throughput under a broad variety of traffic input patterns. Most major packet networks uses some form of adaptive routing where the routes used to route between source-destination pairs may change in response to congestion A third classification that is more related to ad-hoc networks is to classify the routing algorithms as either proactive or reactive. Proactive protocols attempt to continuously evaluate the routes within the network, so that when a packet needs to be forwarded, the route is value india, already known and can be immediately used. The family of Distance-Vector protocols is an example of a proactive scheme.
Reactive protocols, on the other hand, invoke a route determination procedure on demand only. Thus, when a route is needed, some sort of practice world history essay, global search procedure is employed. The family of classical flooding algorithms belongs to the reactive group. Proactive schemes have the advantage that when a route is value education essay india, needed, the delay before actual packets can be sent is very small. On the other side proactive schemes needs time to converge to essay introduction, a steady state. This can cause problems if the topology is changing frequently. India? 15 3 Ad-hoc routing protocols This chapter describes the ap lang different ad-hoc routing protocols that we have chosen to essay india, simulate and analyze.
3.1 Desirable properties If the conventional routing protocols do not meet our demands, we need a new routing protocol. The question is what properties such protocols should have? These are some of the properties  that are desirable: Distributed operation The protocol should of course be distributed. It should not be dependent on a centralized controlling node. This is the essay case even for stationary networks. The difference is that nodes in education india, an ad-hoc network can enter/leave the network very easily and because of mobility the network can be partitioned. Loop free To improve the overall performance, we want the routing protocol to guarantee that the routes supplied are loop-free. This avoids any waste of bandwidth or CPU consumption. Practice Dbq Ap World? Demand based operation To minimize the control overhead in the network and thus not wasting network resources more than necessary, the education protocol should be reactive. This means that the protocol should only ap lang analysis prompt, react when needed and that the protocol should not periodically broadcast control information. Value India? Unidirectional link support The radio environment can cause the cause of domestic essay formation of value, unidirectional links.
Utilization of these links and compare texting essay not only the bi-directional links improves the routing protocol performance. Security The radio environment is especially vulnerable to essay, impersonation attacks, so to ensure the wanted behavior from the routing protocol, we need some sort of preventive security measures. Authentication and analysis essay encryption is value education essay india, probably the way to go and memoir class the problem here lies within distributing keys among the nodes in the ad-hoc network. Education India? There are also discussions about using IP-sec  that uses tunneling to transport all packets. Power conservation The nodes in an ad-hoc network can be laptops and thin clients, such as PDAs that are very limited in battery power and therefore uses some sort of stand-by mode to practice, save power.
It is therefore important that the routing protocol has support for education essay these sleep-modes. Multiple routes To reduce the number of reactions to topological changes and congestion multiple routes could be used. If one route has become invalid, it is possible that another stored route could still be valid and english language thus saving the routing protocol from essay initiating another route discovery procedure. Quality of service support Some sort of analysis essay prompt, Quality of Service support is essay india, probably necessary to incorporate into the routing protocol. This has a lot to do with what these networks will be used for. It could for instance be real-time traffic support. None of the proposed protocols from english language MANET have all these properties, but it is necessary to remember that the protocols are still under development and are probably extended with more functionality. The primary function is still to value essay, find a route to ap lang analysis essay prompt, the destination, not to find the value india best/optimal/shortest-path route. The remainder of this chapter will describe the different routing protocols and analyze them theoretically.
16 3.2 MANET IETF has a working group named MANET (Mobile Ad-hoc Networks)  that is working in compare, the field of adhoc networks. Value Education Essay? They are currently developing routing specifications for ad-hoc IP networks that support scaling to a couple of hundred nodes. Their goal is to be finished in the end of year 1999 and then introduce these specifications to the Internet standard tracks. Even if MANET currently is working on memoir thesis routing protocols, it also serves as a meeting place and forum, so people can discuss issues concerning ad-hoc networks. Currently they have seven routing protocol drafts: N N N N N N N N AODV - Ad-hoc On Demand Distance Vector  ZRP - Zone Routing Protocol  TORA / IMEP - Temporally Ordered Routing Algorithm / Internet MANET Encapsulation Protocol  DSR - Dynamic Source Routing  CBRP - Cluster Based Routing Protocol  CEDAR - Core Extraction Distributed Ad hoc Routing  AMRoute – Ad-hoc Multicast Routing Protocol  OLSR - Optimized Link State Routing Protocol  Of these proposed protocols we have chosen to analyze AODV, DSR, ZRP, CBRP and TORA theoretically. We have also analyzed DSDV, which is a proactive approach, as opposed to the other reactive protocols. We have not analyzed AMRoute because it is a multicast routing protocol, neither CEDAR because it is primary a QoS routing protocol, nor OLSR, because it was submitted as an Internet draft so late. In those cases where a protocol supports both unicast and multicast routing we have only looked at the unicast routing part.
Of the theoretically analyzed protocols we have done simulations on AODV and DSR. 3.3 Destination Sequenced Distance Vector - DSDV 3.3.1 Description DSDV  is a hop-by-hop distance vector routing protocol that in education essay, each node has a routing table that for and contrast essay all reachable destinations stores the next-hop and number of value india, hops for vs. calling that destination. Like distance-vector, DSDV requires that each node periodically broadcast routing updates. Value Education Essay India? The advantage with DSDV over traditional distance vector protocols is that DSDV guarantees loop-freedom. To guarantee loop-freedom DSDV uses a sequence numbers to tag each route. The sequence number shows the analysis essay freshness of a route and routes with higher sequence numbers are favorable. A route R is considered more favorable than R' if R has a greater sequence number or, if the routes have the same sequence number but R has lower hop-count. The sequence number is increased when a node A detects that a route to value essay, a destination D has broken. So the next time node A advertises its routes, it will advertise the route to memoir, D with an infinite hop-count and a sequence number that is larger than before. DSDV basically is distance vector with small adjustments to make it better suited for value education india ad-hoc networks.
These adjustments consist of triggered updates that will take care of immigration outline, topology changes in the time between broadcasts. To reduce the amount of education, information in english essay, these packets there are two types of update messages defined: full and incremental dump. The full dump carries all available routing information and the incremental dump that only carries the information that has changed since the last dump. 3.3.2 Properties Because DSDV is dependent on periodic broadcasts it needs some time to converge before a route can be used. Value Education? This converge time can probably be considered negligible in a static wired network, where the topology is and effect, not changing so frequently. In an ad-hoc network on value education the other hand, where the topology is expected to be very dynamic, this converge time will probably mean a lot of dropped packets before a valid route is detected. The periodic broadcasts also add a large amount of overhead into the network. 17 3.4 Ad-hoc On Demand Distance vector - AODV 3.4.1 Description The Ad Hoc On-Demand Distance Vector (AODV)  routing protocol enables multi-hop routing between participating mobile nodes wishing to establish and maintain an ad-hoc network. AODV is based upon the distance vector algorithm. Practice Dbq Ap World History? The difference is that AODV is reactive, as opposed to proactive protocols like DV, i.e. AODV only requests a route when needed and does not require nodes to maintain routes to destinations that are not actively used in education essay, communications.
As long as the endpoints of a communication connection have valid routes to each other, AODV does not play any role. Features of this protocol include loop freedom and that link breakages cause immediate notifications to be sent to the affected set of for research, nodes, but only that set. Additionally, AODV has support for multicast routing and avoids the Bellman Ford counting to infinity problem . The use of destination sequence numbers guarantees that a route is fresh. Education? The algorithm uses different messages to discover and maintain links. Cause And Effect Of Domestic Violence Essay? Whenever a node wants to try and find a route to another node, it broadcasts a Route Request (RREQ) to all its neighbors. The RREQ propagates through the network until it reaches the value destination or a node with a fresh enough route to and contrast texting, the destination. Then the route is value india, made available by unicasting a RREP back to the source. The algorithm uses hello messages (a special RREP) that are broadcasted periodically to the immediate neighbors. These hello messages are local advertisements for the continued presence of the node and neighbors using routes through the class broadcasting node will continue to essay, mark the routes as valid. If hello messages stop coming from class thesis a particular node, the neighbor can assume that the node has moved away and mark that link to essay, the node as broken and notify the affected set of nodes by class, sending a link failure notification (a special RREP) to that set of nodes.
AODV also has a multicast route invalidation message, but because we do not cover multicast in this report we will not discuss this any further. Route table management AODV needs to education essay, keep track of the following information for each route table entry: N N N N N N N Destination IP Address: IP address for the destination node. Destination Sequence Number: Sequence number for this destination. Hop Count: Number of hops to the destination. Next Hop: The neighbor, which has been designated to forward packets to the destination for this route entry. Lifetime: The time for which the route is considered valid. Active neighbor list: Neighbor nodes that are actively using this route entry. Request buffer: Makes sure that a request is only processed once. Essay? Route discovery A node broadcasts a RREQ when it needs a route to a destination and value education essay does not have one available. This can happen if the route to the destination is unknown, or if a previously valid route expires. After broadcasting a RREQ, the node waits for a RREP.
If the reply is cause violence, not received within a certain time, the node may rebroadcast the RREQ or assume that there is no route to the destination. Forwarding of RREQs is done when the node receiving a RREQ does not have a route to the destination. It then rebroadcast the RREQ. The node also creates a temporary reverse route to the Source IP Address in its routing table with next hop equal to the IP address field of the neighboring node that sent the broadcast RREQ. This is value, done to keep track of and contrast texting vs. calling essay, a route back to the original node making the request, and might be used for an eventual RREP to find its way back to the requesting node. The route is temporary in education essay india, the sense that it is valid for ap lang analysis a much shorter time, than an actual route entry. When the essay india RREQ reaches a node that either is the compare and contrast destination node or a node with a valid route to the destination, a RREP is generated and unicasted back to the requesting node.
While this RREP is forwarded, a route is created to value essay india, the destination and when the RREP reaches the source node, there exists a route from the source to the destination. Ap Lang Analysis Prompt? 18 Route maintenance When a node detects that a route to a neighbor no longer is valid, it will remove the routing entry and india send a link failure message, a triggered route reply message to the neighbors that are actively using the memoir class route, informing them that this route no longer is valid. Value Education India? For this purpose AODV uses a active neighbor list to memoir, keep track of the neighbors that are using a particular route. The nodes that receive this message will repeat this procedure. Education? The message will eventually be received by the affected sources that can chose to either stop sending data or requesting a new route by sending out and effect violence, a new RREQ. 3.4.2 Properties The advantage with AODV compared to classical routing protocols like distance vector and link-state is that AODV has greatly reduced the value essay number of routing messages in the network. Essay? AODV achieves this by value essay india, using a reactive approach. This is probably necessary in class, an ad-hoc network to get reasonably performance when the topology is changing often. AODV is value essay india, also routing in the more traditional sense compared to for instance source routing based proposals like DSR (see 3.5). The advantage with a more traditional routing protocol in an ad-hoc network is that connections from the ad-hoc network to a wired network like the Internet is dbq ap history, most likely easier.
The sequence numbers that AODV uses represents the freshness of a route and is increased when something happens in the surrounding area. The sequence prevents loops from being formed, but can however also be the value india cause for new problems. What happens for instance when the memoir class sequence numbers no longer are synchronized in the network? This can happen when the network becomes partitioned, or the sequence numbers wrap around. Education India? AODV only support one route for each destination. Memoir Thesis? It should however be fairly easy to education, modify AODV, so that it supports several routes per violence, destination. Instead of requesting a new route when an old route becomes invalid, the next stored route to that destination could be tried.
The probability for that route to still be valid should be rather high. Although the Triggered Route Replies are reduced in education india, number by and contrast vs. calling essay, only sending the Triggered Route Replies to affected senders, they need to traverse the whole way from the failure to value essay, the senders. This distance can be quite high in numbers of hops. AODV sends one Triggered RREP for every active neighbor in the active neighbor list for all entries that have been affected of a link failure. Of Domestic Essay? This can mean that each active neighbor can receive several triggered RREPs informing about the same link failure, but for value india different destinations, if a large fraction of the network traffic is routed through the same node and this node goes down. An aggregated solution would be more appropriate here.
AODV uses hello messages at the IP-level. This means that AODV does not need support from the link layer to practice world essay, work properly. Education Essay India? It is however questionable if this kind of protocol can operate with good performance without support from the link layer. The hello messages adds a significant overhead to the protocol. AODV does not support unidirectional links.
When a node receives a RREQ, it will setup a reverse route to the source by class, using the node that forwarded the RREQ as nexthop. India? This means that the thesis route reply, in most cases is unicasted back the same way as the essay route request used. Practice World History? Unidirectional link support would make it possible to utilize all links and not only the essay india bi-directional links. It is however questionable if unidirectional links are desirable in a real environment. The acknowledgements in thesis, the MAC protocol IEEE 802.11 would for instance not work with unidirectional links. 19 3.5 Dynamic Source Routing - DSR 3.5.1 Description Dynamic Source Routing (DSR)  also belongs to the class of reactive protocols and allows nodes to dynamically discover a route across multiple network hops to value india, any destination. Source routing means that each packet in its header carries the complete ordered list of history essay, nodes through which the packet must pass. DSR uses no periodic routing messages (e.g. no router advertisements), thereby reducing network bandwidth overhead, conserving battery power and avoiding large routing updates throughout the ad-hoc network. Instead DSR relies on education essay support from the MAC layer (the MAC layer should inform the routing protocol about english essay link failures). The two basic modes of operation in DSR are route discovery and route maintenance. Route discovery Route discovery is the mechanism whereby a node X wishing to send a packet to Y, obtains the source route to Y. Node X requests a route by broadcasting a Route Request (RREQ) packet.
Every node receiving this RREQ searches through its route cache for a route to the requested destination. Value Education? DSR stores all known routes in its route cache. If no route is found, it forwards the RREQ further and adds its own address to dbq ap world history essay, the recorded hop sequence. This request propagates through the network until either the destination or a node with a route to the destination is reached. When this happen a Route Reply (RREP) is unicasted back to the originator. This RREP packet contains the sequence of education essay india, network hops through which it may reach the target. In Route Discovery, a node first sends a RREQ with the maximum propagation limit (hop limit) set to outline, zero, prohibiting its neighbors from rebroadcasting it.
At the cost of a single broadcast packet, this mechanism allows a node to query the value education india route caches of all its neighbors. Practice Dbq Ap World? Nodes can also operate their network interface in promiscuous mode, disabling the interface address filtering and causing the network protocol to receive all packets that the essay india interface overhears. These packets are scanned for useful source routes or route error messages and then discarded. The route back to compare vs. calling, the originator can be retrieved in several ways. The simplest way is to reverse the hop record in value india, the packet. However this assumes symmetrical links. To deal with this, DSR checks the route cache of the replying node. If a route is found, it is used instead.
Another way is to piggyback the reply on a RREQ targeted at the originator. Ap Lang Essay Prompt? This means that DSR can compute correct routes in the presence of asymmetric (unidirectional) links. Once a route is found, it is stored in the cache with a time stamp and the route maintenance phase begins. Route maintenance Route maintenance is the mechanism by which a packet sender S detects if the network topology has changed so that it can no longer use its route to the destination D. This might happen because a host listed in value essay, a source route, move out of wireless transmission range or is turned off making the route unusable. A failed link is detected by either actively monitoring acknowledgements or passively by running in promiscuous mode, overhearing that a packet is forwarded by immigration outline for research paper, a neighboring node. When route maintenance detects a problem with a route in value education essay india, use, a route error packet is sent back to the source node. When this error packet is received, the hop in error is removed from this hosts route cache, and all routes that contain this hop are truncated at this point.
3.5.2 Properties DSR uses the key advantage of source routing. Intermediate nodes do not need to maintain up-to-date routing information in order to route the packets they forward. There is also no need for periodic routing advertisement messages, which will lead to reduce network bandwidth overhead, particularly during periods when little or no significant host movement is taking place. Battery power is also conserved on the mobile hosts, both by not sending the advertisements and by not needing to receive them, a host could go down to ap lang analysis, sleep instead. This protocol has the advantage of learning routes by value essay, scanning for information in packets that are received. A route from A to C through B means that A learns the route to C, but also that it will learn the route to B. The source route will also mean that B learns the compare and contrast texting route to A and C and that C learns the route to A and education essay B. And Contrast Vs. Calling? This form of active learning is india, very good and and effect of domestic essay reduces overhead in the network. 20 However, each packet carries a slight overhead containing the source route of the packet. This overhead grows when the education packet has to go through more hops to reach the destination. So the and contrast vs. calling essay packets sent will be slightly bigger, because of the overhead.
Running the interfaces in promiscuous mode is a serious security issue. Since the address filtering of the interface is turned off and value education essay all packets are scanned for information. A potential intruder could listen to all packets and scan them for cause and effect of domestic violence useful information such as passwords and credit card numbers. Applications have to provide the security by encrypting their data packets before transmission. The routing protocols are prime targets for impersonation attacks and value education must therefore also be encrypted. And Effect Of Domestic Violence? One way to achieve this is to use IPsec . DSR also has support for unidirectional links by the use of piggybacking the source route a new request. This can increase the performance in scenarios where we have a lot of unidirectional links.
We must however have a MAC protocol that also supports this. 3.6 Zone Routing Protocol - ZRP 3.6.1 Description Zone Routing Protocol (ZRP)  is value education essay india, a hybrid of analysis prompt, a reactive and a proactive protocol. It divides the value network into several routing zones and specifies two totally detached protocols that operate inside and between the memoir class thesis routing zones. The Intrazone Routing Protocol (IARP) operates inside the value routing zone and learns the minimum distance and routes to all the nodes within the zone. The protocol is analysis essay prompt, not defined and can include any number of proactive protocols, such as Distance Vector or link-state routing. Education? Different zones may operate with different intrazone protocols as long as the protocols are restricted to dbq ap history, those zones. A change in topology means that update information only propagates within the education affected routing zones as opposed to affecting the entire network. The second protocol, the Interzone Routing Protocol (IERP) is reactive and is used for finding routes between different routing zones.
This is useful if the destination node does not lie within the routing zone. The protocol then broadcasts (i.e. bordercasts) a Route REQuest (RREQ) to all border nodes within the routing zone, which in turn forwards the request if the destination node is not found within their routing zone. This procedure is repeated until the requested node is found and a route reply is sent back to the source indicating the texting vs. calling essay route. IERP uses a Bordercast Resolution Protocol (BRP)  that is education essay, included in practice dbq ap history essay, ZRP. BRP provides bordercasting services, which do not exist in IP. Bordercasting is the process of sending IP datagrams from education one node to all its peripheral nodes.
BRP keeps track of the illegal immigration outline paper peripheral nodes and resolves a border cast address to the individual IP-addresses of the essay india peripheral nodes. The message that was bordercasted is then encapsulated into illegal immigration outline for research, a BRP packet and sent to each peripheral node. Routing Zone A routing zone is defined as a set of education, nodes, within a specific minimum distance in ap lang prompt, number of education essay, hops from the node in question. The distance is referred to as the zone radius. In the illegal outline example network (Figure 3), node S, A, F, B, C, G and value education india H, all lie within a radius of two from node F. Even though node B also has a distance of 3 hops from node F, it is thesis, included in the zone since the value education india shortest distance is only 2 hops. Compare And Contrast Texting Essay? Border nodes or peripheral nodes are nodes whose minimum distance to the node in question is equal exactly to the zone radius. In Figure 3, nodes B and F are border nodes to S. Value Essay? Consider the network in Figure 3. Node S wants to send a packet to practice dbq ap world, node D. Since node D is education india, not in the routing zone of S, a route request is sent to and effect of domestic, the border nodes B and F. Each border node checks to see if D is in essay india, their routing zone. Neither B nor F finds the requested node in their routing zone; thus the request is forwarded to the respectively border nodes. Language Essay Introduction? F sends the request to S, B, C and H while B sends the request to S, F, E and G. Now the requested node D is found within the education essay routing zone of and contrast texting, both C and E thus a reply is generated and sent back towards the education essay source node S. 21 B E A Zone for D C S D F Zone for S G H Zone for F Figure 3: Network using ZRP. Essay? The dashed squares show the essay india routing zones for nodes S and D. To prevent the requests from going back to previously queried routing zone, a Processed Request List is used. This list stores previously processed requests and if a node receives a request that it already has processed, it is simply dropped.
3.6.2 Properties ZRP is and contrast texting vs. calling essay, a very interesting protocol and can be adjusted of education india, its operation to world, the current network operational conditions (e.g. change the routing zone diameter). However this is not done dynamically, but instead it is suggested that this zone radius should be set by the administration of the network or with a default value by value, the manufacturer. The performance of illegal immigration outline paper, this protocol depends quite a lot on this decision. Since this is a hybrid between proactive and reactive schemes, this protocol use advantages from both. Routes can be found very fast within the routing zone, while routes outside the zone can be found by value education essay, efficiently querying selected nodes in the network. One problem is however that the proactive intrazone routing protocol is class thesis, not specified. The use of different intrazone routing protocols would mean that the nodes would have to support several different routing protocols. This is not a good idea when dealing with thin clients. Value? It is better to use the same intrazone routing protocol in the entire network. Dbq Ap Essay? ZRP also limits propagation of information about topological changes to the neighborhood of the change only (as opposed to value education essay india, a fully proactive scheme, which would basically flood the entire network when a change in topology occurred).
However, a change in essay, topology can affect several routing zones. 3.7 Temporally-Ordered Routing Algorithm - TORA 3.7.1 Description Temporally Ordered Routing Algorithm (TORA)  is a distributed routing protocol. Essay? The basic underlying algorithm is outline, one in a family referred to as link reversal algorithms. TORA is value essay, designed to minimize reaction to topological changes. A key concept in its design is that control messages are typically localized to a very small set of nodes. It guarantees that all routes are loop-free (temporary loops may form), and typically provides multiple routes for any source/destination pair.
It provides only the routing mechanism and depends on essay Internet MANET Encapsulation Protocol (IMEP ) for other underlying functions. TORA can be separated into value education india, three basic functions: creating routes, maintaining routes, and illegal paper erasing routes. The creation of routes basically assigns directions to value essay india, links in an undirected network or portion of the network, building a directed acyclic graph (DAG) rooted at the destination (See Figure 4). 22 D Figure 4: Directed acyclic graph rooted at destination. TORA associates a height with each node in the network. All messages in the network flow downstream, from a node with higher height to a node with lower height. Routes are discovered using Query (QRY) and Update (UPD) packets. Ap Lang? When a node with no downstream links needs a route to a destination, it will broadcast a QRY packet. Education India? This QRY packet will propagate through the network until it reaches a node that has a route or the destination itself. Such a node will then broadcast a UPD packet that contains the practice dbq ap node height. Every node receiving this UPD packet will set its own height to a larger height than specified in the UPD message.
The node will then broadcast its own UPD packet. This will result in a number of directed links from the originator of the QRY packet to the destination. Value Education Essay India? This process can result in multiple routes. Maintaining routes refers to reacting to topological changes in the network in a manner such that routes to the destination are re-established within a finite time, meaning that its directed portions return to a destination-oriented graph within a finite time. Upon detection of a network partition, all links in the portion of the illegal for research network that has become partitioned from the destination are marked as undirected to erase invalid routes. The erasing of routes is done using clear (CLR) messages.
3.7.2 Properties The protocols underlying link reversal algorithm will react to link changes through a simple localized single pass of the distributed algorithm. This prevents CLR packets to propagate too far in value essay india, the network. Analysis Essay? A comparison made by the CMU Monarch project has however shown that the overhead in TORA is quite large because of the use of value education essay, IMEP. Practice World History? The graph is rooted at the destination, which has the value education essay lowest height. However, the source originating the QRY does not necessarily have the highest height. This can lead to the situation, where multiple routes are possible from the source to the destination, but only one route will be discovered. The reason for this is that the texting essay height is initially based on value essay india the distance in number of hops from the essay introduction destination.
23 3.8 Internet MANET Encapsulation Protocol - IMEP 3.8.1 Description IMEP  is a protocol designed to support the operation of many routing protocols in Ad-hoc networks. The idea is to have a common general protocol that all routing protocols can make use of (see Figure 5). It incorporates many common mechanisms that the upper-layer protocol may need. Education Essay? These include: N N N N N Link status sensing Control message aggregation and encapsulation Broadcast reliability Network-layer address resolution Hooks for practice dbq ap history interrouter security authentication procedures IMEP also provides an architecture for MANET router identification, interface identification and addressing. IMEPs purpose is to improve overall performance by reducing the number of control messages and to put common functionality into one unified, generic protocol useful to all upper-level routing protocols. Value Education Essay? Routing IMEP IP Figure 5: IMEP in the protocol stack. Of the currently purposed protocols, only TORA and OLSR use IMEP. It must however be noted that TORA and IMEP where designed by the same author. 3.8.2 Properties The idea to have a general protocol for common basic features is good, but from a performance point of view this is not such a good idea. And Effect Of Domestic Violence? It adds another layer to the protocol stack. As the work by the CMU Monarch projects has shown , IMEP generates a lot of overhead, mainly because of IMEPs neighbor discovery mechanism that generates at least one hello message per second, but also because of the reliable in-order delivery of the education essay india packets that IMEP provides.
3.9 Cluster Based Routing Protocol - CBRP 3.9.1 Description The idea behind CBRP  is to divide the nodes of an ad-hoc network into a number of overlapping or disjoint clusters. Memoir Class Thesis? One node is elected as cluster head for each cluster. This cluster head maintains the membership information for value india the cluster. Inter-cluster routes (routes within a cluster) are discovered dynamically using the membership information. Essay Prompt? 24 CBRP is based on source routing, similar to DSR. This means that intracluster routes (routes between clusters) are found by flooding the network with Route Requests (RREQ). The difference is that the cluster structure generally means that the number of nodes disturbed are much less. Flat routing protocols, i.e. only one level of hierarchy, might suffer from value essay india excessive overhead when scaled up. And Contrast Texting? CBRP is like the other protocols fully distributed. This is necessary because of the very dynamic topology of the ad-hoc network. Furthermore, the protocol takes into consideration the existence of india, unidirectional links.
Link sensing Each node in and effect violence, CBRP knows its bi-directional links to its neighbors as well as unidirectional links from its neighbors to education india, itself. To handle this, each node must maintain a Neighbor Table (see Table 1). Table 1: Neighbor ID Neighbor 1 Neighbor 2 … Neighbor n Neighbor table. Link status Bi/unidirectional link to me Bi/unidirectional link to me … Bi/unidirectional link to me Role Is 1 a cluster head or member Is 2 a cluster head or member … Is n a cluster head or member Each node periodically broadcasts its neighbor table in a hello message. The hello message contains the node ID, the nodes role (cluster head, cluster member or undecided) and the neighbor table. The hello messages are used to update the neighbor tables at each node. If no hello message is received from a certain node, that entry will be removed from the table. Clusters The cluster formation algorithm is very simple, the node with lowest node ID is analysis essay, elected as the cluster head. Education India? The nodes use the english introduction information in essay, the hello messages to decide whether or not they are the cluster heads. The cluster head regards all nodes it has bi-directinal links to as its member nodes.
A node regards itself as a member node to a particular cluster if it has a bi-directinal link to the cluster head. It is possible for a node to belong to several clusters. English Introduction? Cluster 1 Cluster 2 3 4 Cluster head Cluster head 1 2 6 Figure 6: 5 Bi-directional linked clusters. 25 Clusters are identified by their respective cluster heads, which means that the cluster head must change as infrequently as possible. The algorithm is therefore not a strict lowest ID clustering algorithm. A noncluster head never challenges the india status of an compare and contrast texting, existing cluster head. Only when two cluster-heads move next to each other, will one of them lose the role as cluster head. In Figure 6 node 1 is cluster head for cluster 1 and node 2 is cluster head for cluster 2. Routing Routing in education essay india, CBRP is based on source routing and the route discovery is practice world history, done, by flooding the network with Route Requests (RREQ). The clustering approach however means that fewer nodes are disturbed. This, because only the cluster heads are flooded.
If node X needs a route to node Y, node X will send out a RREQ, with a recorded source route listing only itself initially. Any node forwarding this packet will add its own ID in this RREQ. Each node forwards a RREQ only value essay india, once and it never forwards it to node that already appears in the recorded route. In CBRP, a RREQ will always follow a route with the following pattern: Source-Cluster head-Gateway-Cluster head-Gateway- . -Destination A gateway node for a cluster is a node that knows that it has a bi-directional or a unidirectional link to a node in another cluster. In Figure 6, node 6 is gateway node for cluster 1 and node 4 is gateway node for cluster 2. The source unicasts the RREQ to its cluster head. Texting Vs. Calling Essay? Each cluster-head unicasts the RREQ to essay india, each of its bidirectionally linked neighbor clusters, which has not already appeared in the recorded route through the corresponding gateway. There does not necessarily have to essay, be an actual bi-directional link to value education essay, a bi-directional linked neighbor cluster. For instance, in Figure 6 cluster 1 has a unidirectional link to class thesis, cluster 2 through node 3 and cluster 2 has a unidirectional link to essay india, cluster 1 through node 5, and the clusters are therefore bidirectional linked neighbor clusters. This procedure continues until the target is found or another node can supply the route. When the RREQ reaches the target, the target may chose to memorize the reversed route to the source. It then copies the compare and contrast essay recorded route to a Route Reply packet and sends it back to the source.
3.9.2 Properties This protocol has a lot of common features with the earlier discussed protocols. It has a route discovery and route removal operation that has a lot in common with DSR and AODV. The clustering approach is value education essay, probably a very good approach when dealing with large ad-hoc networks. The solution is more scalable than the other protocols, because it uses the clustering approach that limits the number of messages that need to be sent. CBRP also has the advantage that it utilizes unidirectional links.
One remaining question is however how large each cluster should be. This parameter is critical to how the protocol will behave. 3.10 Comparison So far, the protocols have been analyzed theoretically. Table 2 summarizes and compares the result from these theoretical/qualitative analyses and shows what properties the english protocols have and do not have. India? As it can be seen from Table 2, none of the protocols support power conservation or Quality of Service. This is however work in progress and will probably be added to the protocols. Violence Essay? All protocols are distributed, thus none of the value education india protocols is dependent on a centralized node and can therefore easily reconfigure in the event of topology changes.
26 Table 2: Comparison between ad-hoc routing protocols. DSDV AODV DSR ZRP Loop-free Yes Yes Yes Yes Multiple routes Distributed Reactive Unidirectional link support QoS Support Multicast Security Power conservation Periodic broadcasts No Yes No No No No No No Yes No Yes Yes No No Yes No No Yes Yes Yes Yes Yes No No No No No No Yes Partially No No No No No Yes Requires reliable or sequenced data No No No No TORA/ IMEP No, short lived loops Yes Yes Yes No No No No No Yes (IMEP) Yes CBRP Yes Yes Yes Yes Yes No No No No Yes No DSDV is the only proactive protocol in this comparison. It is also the english introduction protocol that have most in common with traditional routing protocol in wired networks. The sequence numbers were added to ensure loop-free routes. DSDV will probably be good enough in networks, which allows the protocol to converge in reasonable time. Education Essay India? This however means that the mobility cannot be too high. The authors of DSDV came to the same conclusions and designed AODV, which is cause of domestic, a reactive version of DSDV. They also added multicast capabilities, which will enhance the performance significantly when one node communicates with several nodes.
The reactive approach in AODV has many similarities with the reactive approach of DSR. They both have a route discovery mode that uses request messages to find new routes. The difference is that DSR is based on source routing and will learn more routes than AODV. DSR also has the advantage that it supports unidirectional links. DSR has however one major drawback and it is the source route that must be carried in each packet. This can be quite costly, especially when QoS is going to be used. Education India? ZRP and CBRP are two very interesting proposals that divide the network into ap lang essay prompt, several zones/clusters. This approach is probably a very good solution for large networks. Within the zones/clusters they have a more proactive scheme and between the zones/clusters they have a reactive scheme that have many similarities with the value education operation of AODV and DSR. English? They have for essay instance a route discovery phase that sends request through the network. English Introduction? The difference between ZRP and education essay CBRP is english essay, how the network is divided.
In ZRP all zones are overlapping and in CBRP clusters can be both overlapping and disjoint. None of the essay india presented protocols are adaptive, meaning that the protocols do not take any smart routing decisions when the traffic load in the network is illegal paper, taken into consideration. As a route selection criteria the proposed protocols use metrics such as shortest number of hops and value education quickest response time to a request. English Introduction? This can lead to the situation where all packets are routed through the same node even if there exist better routes where the traffic load is not as large. 27 4 Simulation Environment The simulator we have used to essay, simulate the ad-hoc routing protocols in texting vs. calling, is the Network Simulator 2 (ns)  from Berkeley. To simulate the mobile wireless radio environment we have used a mobility extension to ns that is developed by the CMU Monarch project at Carnegie Mellon University. 4.1 Network Simulator Network simulator 2 is the value result of an on-going effort of research and development that is memoir class thesis, administrated by value education essay, researchers at Berkeley. It is a discrete event simulator targeted at networking research. It provides substantial support for simulation of compare and contrast essay, TCP, routing, and india multicast protocols. The simulator is written in C++ and a script language called OTcl2.
Ns uses an Otcl interpreter towards the language introduction user. This means that the user writes an OTcl script that defines the network (number of nodes, links), the traffic in the network (sources, destinations, type of traffic) and education which protocols it will use. This script is then used by ns during the simulations. Outline? The result of the simulations is an output trace file that can be used to do data processing (calculate delay, throughput etc) and to india, visualize the simulation with a program called Network Animator (NAM). See Appendix C for immigration outline a screenshot of NAM. NAM is a very good visualization tool that visualizes the packets as they propagate through the value education network. An overview of cause and effect violence, how a simulation is done in ns is shown in Figure 7. Otcl script Network Simulator 2 Output Data processing Network Animator Figure 7: Network simulator 2. The current version3 of the Network simulator does not support mobile wireless environments. The Network simulator alone is only intended for stationary networks with wired links. Value? This caused us some problems in the beginning of this master thesis.
We needed mobility and therefore started to design and implement a mobility model that would extend the simulator. We also started to implement the AODV protocol. This implementation of AODV is ap lang analysis prompt, compatible with NAM and therefore gives a good picture of value education india, how AODV behaves. It is very easy to follow for instance the route discovery procedure. About two months later, in and effect, August 1998, two separate mobility extensions were released. Value Education Essay? These extensions had everything that we wanted from an english essay, extension, so we decided to value india, use one of them. This however meant that the implementation of AODV that we made earlier no longer was compatible and had to be ported. 2 3 Object Tool Command Language Network simulator 2.1b3 28 4.2 Mobility extension There currently exist two mobility extensions to ns.
These are: N N Wireless mobility extension developed by the CMU Monarch projects . Mobility support, mobile IP and wireless channel support developed by C. Perkins at Sun Microsystems . Immigration For Research? The ns group at education essay, Berkeley has as intention to memoir class thesis, integrate both these extensions to ns. This work is however not complete yet. We have chosen to use the CMU Monarch extension, because this extension is targeted at ad-hoc networks. The version of the extension that we have worked with4 adds the following features5 to value education essay india, the Network simulator.
Node mobility Each mobile node is an independent entity that is responsible for computing its own position and of domestic essay velocity as a function of time. Education Essay India? Nodes move around according to a movement pattern specified at cause and effect violence essay, the beginning of the value india simulation. Realistic physical layers Propagation models are used to decide how far packets can travel in air. These models also consider propagation delays, capture effects and carrier sense . MAC 802.11 An implementation of the IEEE 802.11 Media Access Protocol (MAC)  protocol was included in the extension. The MAC layer handles collision detection, fragmentation and acknowledgements. This protocol may also be used to detect transmission errors. 802.11 is a CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) protocol. It avoids collisions by checking the channel before using it. If the channel is ap lang analysis essay prompt, free, it can start sending, if not, it must wait a random amount of time before checking again. For each retry an exponential backoff algorithm will be used.
In a wireless environment it cannot be assumed that all stations hear each other. If a station senses the medium, as free, it does not necessarily mean that the medium is free around the receiver area. This problem is known as the value essay hidden terminal problem and to overcome these problems the Collision Avoidance mechanism together with a positive acknowledgement scheme is ap lang essay prompt, used. The positive acknowledgement scheme means that the receiver sends an acknowledgement when it receives a packet. The sender will try to retransmit this packet until it receives the acknowledgement or the number of retransmits exceeds the education india maximum number of retransmits. 802.11 also support power saving and compare and contrast texting essay security. Value Education Essay India? Power saving allows packets to be buffered even if the system is asleep. Security is cause and effect of domestic essay, provided by value education india, an algorithm called Wired Equivalent Privacy (WEP). Illegal Immigration Paper? It supports authentication and encryption. WEP is a Pseudo Random Number Generator (PRNG) and value essay is based on english language essay RSAs RC4. One of the most important features of 802.11 is the ad-hoc mode, which allows users to build up Wireless LANs without an infrastructure (without an access point).
Address Resolution Protocol The Address Resolution Protocol, ARP  is implemented. ARP translates IP-addresses to hardware MAC addresses. This takes place before the packets are sent down to education india, the MAC layer. Ad-hockey Ad-hockey is an application that makes it possible to visualize the mobile nodes as they move around and send/receives packets. Ad-hockey can also be used as a scenario generator tool to create the input files necessary for the simulations. This is done, by positioning nodes in a specified area.
Each node is then given a movement pattern consisting of movement directions at different waypoints, speed, pause times and communication patterns. Screenshots of ad-hockey can be seen in Appendix C. 4 Version 1.0.0-beta, released in the middle of August. At the end of immigration for research, November 1998, the education CMU Monarch projects released version 1.1.0 of the language essay extension. This new version contains some bug fixes and implementations of the AODV and TORA protocols. 5 29 Radio network interfaces This is a model of the hardware that actually transmits the packet onto the channel with a certain power and modulation scheme .
Transmission power The radius of the transmitter with an omni-directional antenna is about 250 meters in education, this extension. Antenna gain and receiver sensitivity Different antennas are available for simulations. Ap Lang Essay? Ad-hoc routing protocols Both DSR and DSDV have been implemented and added to this extension. 4.2.1 Shared media The extension is based on value education essay a shared media model (Ethernet in the air). Analysis Prompt? This means that all mobile nodes have one or more network interfaces that are connected to a channel (see Figure 8). A channel represents a particular radio frequency with a particular modulation and coding scheme. Channels are orthogonal, meaning that packets sent on education india one channel do not interfere with the class transmission and reception of packets on another channel. Education Essay? The basic operation is as follows, every packet that is sent / put on the channel is received / copied to all mobile nodes connected to the same channel.
When a mobile nodes receive a packet, it first determines if it possible for english essay introduction it to receive the packet. This is determined by the radio propagation model, based on the transmitter range, the value essay india distance that the packet has traveled and the amount of bit errors. Mobile Node Mobile Node Mobile Node Channel Figure 8: Shared media model. 4.2.2 Mobile node Each mobile node (Figure 9) makes use of a routing agent for the purpose of calculating routes to other nodes in the ad-hoc network. Packets are sent from the application and are received by the routing agent. The agent decides a path that the packet must travel in essay, order to reach its destination and stamps it with this information. It then sends the packet down to the link layer. The link layer level uses an Address Resolution Protocol (ARP) to value essay india, decide the hardware addresses of immigration for research, neighboring nodes and map IP addresses to their correct interfaces. India? When this information is known, the packet is sent down to the interface queue and awaits a signal from the Multiple Access Control (MAC) protocol.
When the MAC layer decides it is ok to send it onto english language, the channel, it fetches the packet from the value essay india queue and ap lang prompt hands it over to the network interface which in turn sends the packet onto the radio channel. This packet is copied and is delivered to all network interfaces at the time at which the first bit of the packet would begin arriving at the interface in value education, a physical system. Each network interface stamps the packet with the receiving interfaces properties and analysis then invokes the propagation model. The propagation model uses the india transmit and receive stamps to determine the power with which the interface will receive the packet. The receiving network interfaces then use their properties to english language, determine if they actually successfully received the packet, and sends it to essay, the MAC layer if appropriate. If the MAC layer receives the compare and contrast texting vs. calling packet error- and collision- free, it passes the packet to the mobiles entry point. Value India? From there it reaches a demultiplexer, which decides if the packet should be forwarded again, or if it has reached its destination node. Class? If the destination node is reached, the packet is sent to a port demultiplexer, which decides to what application the packet should be delivered. If the packet should be forwarded again the value routing agent will be called and illegal outline for research the procedure will be repeated. 30 Entry point M U X Application Routing Agent Link Layer ARP Queue MAC Propagation model Network Interface Channel Figure 9: A mobile node.
4.3 Simulation overview A typical simulation with ns and value education the mobility extension is shown in Figure 10. Basically it consists of practice dbq ap history, generating the following input files to ns: N N A scenario file that describes the education india movement pattern of the nodes. For Research? A communication file that describes the traffic in the network. These files can be generated by value essay india, drawing them by hand using the dbq ap visualization tool Ad-hockey (see 4.2) or by generating completely randomized movement and communication patterns with a script. These files are then used for value education essay the simulation and as a result from this, a trace file is analysis essay prompt, generated as output. Essay? Prior to the simulation, the language essay parameters that are going to be traced during the simulation must be selected. The trace file can then be scanned and analyzed for the various parameters that we want to value, measure.
This can be used as data for memoir thesis plots with for instance Gnuplot. The trace file can also be used to value india, visualize the simulation run with either Ad-hockey or Network animator. 31 Scenario generation Scenario file Communication file Mobility extension Network Simulator 2 Output files Data processing Ad-hockey GnuPlot Figure 10: Network animator Simulation overview. 4.4 Modifications To be able to illegal outline for research paper, use ns for the simulations, we had to value education, do some modifications. First of all, we did not have the routing protocols we wanted to cause and effect of domestic essay, simulate, so one of the value education india first steps was to implement the protocols. 4.4.1 AODV We have implemented the AODV protocol (for more details, see appendix B). The implementation is done according to the AODV draft  released in August 1998. Analysis Essay? It must however be noted that a new version of the draft  was released in the end of November 1998. The new draft contains some changes that would enhance the performance. Value Education Essay India? These changes that affect the essay unicast routing part is primarily: N N Reduced or complete elimination of hello messages. Updates to important parameters to value essay, reflect recent simulation experiences.
To be able to test how the hello messages and link layer support affects the behavior of the memoir class protocol we have implemented three versions: N N N AODV with only india, IP-based hello messages AODV with only Link Layer notification of broken links AODV with both IP-based hello messages and Link layer notification of and effect of domestic violence essay, broken links The implementation of the different versions has some major differences that will affect the essay performance. First of all AODV with only MAC-layer support will not get the routes to the neighbors installed in outline paper, the routing table, neither will it update the routes to the neighbor who forwarded a message to you. Both AODV versions that have hello messages will have this neighbor detection process that keeps track of the neighbors. This means that the value education essay protocols with this feature will have more information in ap lang prompt, the 32 routing tables. Without this support, buffering of the packets may be necessary while a request is value india, sent out in search for a node that could be a neighbor. It must however be noted that the removal of and effect violence essay, hello messages somewhat changes the value education india behavior of the compare and contrast texting AODV protocol. The hello messages add overhead to the protocol, but also gives us some prior knowledge of link breakages. Removing the hello messages makes the protocol completely on-demand, broken links can only be detected when actually sending something on value essay the broken link. Illegal Immigration For Research Paper? The DSR implementation that was included in the mobility extension used a sendbuffer that buffered all packets that the application sent while the routing protocol searched for a route. Value Essay? To get a fair comparison of the protocols we implemented the same feature for AODV. This buffer can hold 64 packets and packets are allowed to stay in vs. calling essay, the buffer for value education 8 seconds.
The parameters that can be adjusted for AODV and the values we have used is cause of domestic violence essay, shown in Table 3. Some of india, these parameters are very important and affects the performance of the protocol in drastic ways. The hello interval is maybe the most important parameter when dealing with AODV that uses hello messages. Dbq Ap Essay? If the interval is too long, link breakages would not be detected fast enough, but if the value india interval is to short, a great amount of extra control overhead would be added. Most of the parameters in Table 3 are obvious. The maximum rate for sending replies prevents a node to do a triggered route reply storm.
This means that AODV in each node is only allowed to send one triggered RREP per second for each broken route. This could for instance happen if a forwarding node receives a lot of data packets that the node no longer has a route for. In this case the outline node should only send a triggered RREP, as a response to value education, the first data packet and if the compare and contrast texting essay node keeps receiving data packets after that, a triggered RREP is only allowed to be sent once per value essay india, second. Table 3: Constants used in the AODV implementation. Parameter Hello interval Active route timeout Route reply lifetime Allowed hello loss Request retries Time between retransmitted requests Time to illegal paper, hold packets awaiting routes Maximum rate for sending replies for a route Value 1,5 s 300 s 300 s 2 3 3s 8s 1/s 4.4.2 DSR The DSR implementation that came with the extension uses promiscuous mode (i.e. eavesdropping), which means that the protocol learns information from packets that it overhears. The question is how realistic this is in essay, a real environment. In a real case scenario we will probably have some sort of encryption, probably IP-Sec that uses IP-Sec tunneling to transport messages. We have made some small change to DSR that makes it possible to turn the analysis eavesdropping feature on value education india and off. The parameters that are configurable for thesis DSR are shown in Table 4. Education? These values are the values specified in the DSR draft and have not been changed. The nonpropagating timeout is the time a node waits for a reply for a nonpropagating search. A nonpropagating search is a request that first goes to the neighbors.
If the neighbors do not answer in this specified amount of a time, a new request that will be forwarded by the neighbors will be sent. Thesis? The sendbuffer in the DSR can hold 64 packets and the packets are allowed to india, stay in the buffer for 30 seconds Table 4: Constants used in english introduction, the DSR implementation. Parameter Time between retransmitted requests Size of source route header carrying n addresses Timeout for nonpropagating search Time to hold packets awaiting routes Maximum rate for sending replies for a route 33 Value 500 ms 4n + 4 bytes 30 ms 30 s 1/s 4.4.3 DSDV The extension also included an implementation of the DSDV protocol. This implementation is actually two implementations that handle the value education india triggered update a little different. In the compare texting first version only a new metric for a destination causes a triggered update to be sent. In the second version, a new sequence number for a destination causes a triggered update to be sent. We have modified DSDV so it always uses the value education essay india version that triggers on new sequence numbers. Language Essay Introduction? This is the education version that, we feel behaves according to memoir class thesis, the specification of DSDV. Value Education? The parameters for DSDV are shown in Table 5 and are as specified in analysis prompt, the DSDV paper .
Table 5: Constants used in the DSDV implementation. Essay India? Parameter Periodic route update interval Periodic updates missed before link declared broken Route advertisement aggregation time Maximum packets buffered per node per vs. calling, destination Value 15 s 3 1s 5 4.4.4 Flooding We have implemented a simple flooding protocol that simply floods all user data packets to all nodes in the network. To have some sort cleverness in value essay, this flooding and avoiding data to bounce back and forth we use a sequence number in each packet. This sequence number is incremented for each new packet. Each node keeps track of cause of domestic violence essay, (source IP, sequence number) for value education india all destinations and does not process a packet if the packet has a sequence number smaller than the stored sequence number. The idea was to do the simulations on the flooding protocol and compare the analysis prompt results with the results for the routing protocols. After some initial simulations on flooding this plan was abandoned. The simulations took too long to complete.
The reason is that flooding generates too many packets (events in the simulator). 4.4.5 The simulator To the actual simulator (ns + extension) we have added some new features to allow us to make the wanted measurements. Value India? Obstacles The visualization/scenario generator tool, Ad-hockey, allows the user to place obstacles (lines and boxes) into the scenario. Texting Essay? The problem is that ns do not use these obstacles for any kind of computation. Two nodes can communicate, even through a wall. We wanted to simulate the education essay protocols in cause and effect of domestic violence, a few realistic scenarios, so we added these computations to ns. The calculations consisted of two parts. Education India? The first part was to store all obstacles in immigration outline for research, a database that we later could use when calculating the intersection points and india the second part was to class thesis, extend the propagation model with the actual computations. The computations merely consisted of deciding if there existed an intersection point between the straight line from the sending node to the receiving node and any obstacle in value education, the database.
If such an intersection point exists, the memoir class communication is education india, simply cut of. No fading of the signal, reflections etc is taken into consideration. Thesis? The model is value education essay india, therefore very simple. Violence? The problem with these computations is value education essay india, that it adds a lot of overhead in the simulations. The simulations will take significantly longer time to complete. The extra computation must be done for all packets. In a large scenario with many nodes that are sending a lot of traffic this will increase the illegal immigration outline for research simulation time significantly. Version management To allow us to test different versions of one protocol simultaneous, we have added a version control to ns. This means that it is possible to give a version number to a protocol when the simulation starts. This version number is given to the specified protocol and it is education, then up to the programmer to use it.
We currently use this feature with both AODV and DSR. Ap Lang Prompt? The different versions are: N N N N N AODV 1 = AODV with only hello messages. AODV 2 = AODV with only MAC-layer feedback. AODV 3 = AODV with both hello messages and MAC-layer feedback. DSR 1 = DSR with eavesdropping. Education Essay? DSR 2 = DSR without eavesdropping. 34 5 Simulation study The protocols that we have simulated are DSDV, AODV and DSR. DSDV is only used to illegal for research, get a comparison of education, how much better/worse the MANET protocols are than an ordinary proactive protocol. The simulations were conducted on an Intel PC with a Pentium-2 processor at 400 MHz, 128 Mbytes of RAM running FreeBSD6. 5.1 Measurements Before we go into the actual simulations, we will discuss which parameters  that are interesting to measure when studying routing protocols in cause and effect, an ad-hoc network.
There are two main performance measures that are substantially affected by the routing algorithm, the average end-to-end throughput (quantity of service) and the average end-to-end delay (quality of service). 5.1.1 Quantitative metrics The measurements that we have conducted can be seen from two angels: externally and internally. The external view is what the application/user sees and the internal view is how the routing protocol behaves. The external measurements are basically the value education essay end-to-end throughput and delay. English Introduction? The internal behavior can further be divided into value india, routing accuracy and routing efficiency. N N Routing Efficiency: How much of the memoir sent data is actually delivered to the destination? How much routing overhead is required to find routes? Routing Accuracy: How accurate, measured in number of hops are the supplied routes compared to the optimal shortest path.
5.1.2 Parameters The metrics has to be measured against value essay some parameter that describes the characteristic behavior of an adhoc network and practice dbq ap can be varied in a controlled way. The parameters that we have chosen to simulate with are: N N N Mobility, which probably is one of the most important characteristics of an ad-hoc network. This will affect the dynamic topology, links will go up and down. Value India? Offered network load. The load that we actually offer the network. Practice History? This can be characterized by three parameters: packet size, number of value education essay india, connections and the rate that we are sending the packets with. Network size (number of compare vs. calling, nodes, the size of the area that the nodes are moving within). The network size basically determines the connectivity. Fewer nodes in the same area mean fewer neighbors to send requests to, but also smaller probability for collisions.
5.1.3 Mobility Because mobility is an important metric when evaluating ad-hoc networks we need some definition of mobility. There exist many definitions of mobility. The CMU Monarch project  has for value education india instance used the pause time in the waypoints as a definition of mobility. If a node has a low pause time, it will almost constantly be moving, which would mean a high mobility. English? If a node has a large pause time it will stand still most of the time and education have a low mobility. We did not think that this mobility definition was good enough, because even if the pause time is low and all nodes are constantly moving, they could all be moving with a very slow speed in the same area. We have defined mobility a little differently. Our definition is based on the relative movement of the practice history essay nodes. This definition gives a very good picture of how the nodes are moving relatively to each other. The definition is as follows: 6 FreeBSD 2.2.6 35 If several nodes move for a certain time, then the mobility is the average change in distance between all nodes over that period of time.
This time is the simulation time T. Mobility is a function of both the education india speed and the movement pattern. It is calculated with a certain sampling rate. During the simulations, we have used 0.1 seconds as sampling rate. Language? This is the education essay india default time when logging the movement in the simulations, so it was appropriate to use the same value when calculating the mobility. Table 6 shows all variables that are used in the equations for the mobility factor. Table 6: Variable name dist(nx, ny)t n i Ax(t) Mx T t Mob Mobility variables.
Description the distance between node x and node y at time t number of cause and effect violence essay, nodes Index Average distance for node x to education essay india, all other nodes at time t Average mobility for immigration outline for research paper node x relative to all other nodes during the entire simulation time Simulation time Granularity, simulation step Mobility for education india entire scenario First of all, the average distance from each node to all other nodes has to be calculated. This has to essay, be done at times t = 0, t = 0+X, t = 0+2X, . t = simulation time. For the node x at time t the formula is: n ¦ dist (n , n ) x Ax(t) = i i1 (5.1) n 1 After that, with the use of (5.1), the average mobility for that particular node has to be calculated. This is the average change in distance during a whole simulation. The mobility for node x is: T t ¦ A (t ) A (t 't ) x Mx = x t0 (5.2) T 't Finally, the mobility for the whole scenario is the sum of the mobility for all nodes (5.2) divided with the number of nodes: n ¦M Mob = i i1 (5.3) n The unit for the mobility factor (5.3) is m/s.
The mobility factor therefore gives a picture of the average speed of the distance change between the nodes. Figure 11 shows some basic examples of how this mobility factor will reflect the actual movement. If the nodes are standing still, this will of course lead to a mobility of 0, but this would also be the case when the nodes relative movement is zero, for example when the nodes are moving in parallel with the same speed. It is value, only when the nodes have a movement relative to each other that the mobility factor will be greater than zero. 36 Our mobility definition reflects how the class thesis mobility affects the value essay dynamic topology, without considering obstacles or surroundings. Standing still 0.0 Parallel movement 0.0 Figure 11: Relative movement 0.0 Example of mobility. The reason for choosing mobility as a parameter in the simulations is first of all that the english language essay mobility is education essay india, one of the most important characteristics of an ad-hoc network. But also because mobility is a parameter that is thesis, easy to grasp for people in general. Everyone has a rather good picture of what it means if the mobility is value essay india, increased.
We have tested the mobility factor to see how it affects the dynamic topology. As it can be seen in Figure 12, the number of link changes is directly proportional to the mobility factor. Memoir Class Thesis? A link change basically means that a link changes state from either up/down to down/up. The plot is the average values for all simulations that we have done using 50 nodes and an environment size of 1000x1000 meters. 3500 3000 Avg nr of link changes 2500 2000 1500 1000 500 0 0 0.5 Figure 12: 1 1.5 2 Mobility 2.5 3 3.5 Relation between the number of link changes and mobility. 37 4 5.2 Simulation setup In this chapter we will describe how the value essay india simulations were done. Compare And Contrast Essay? We have done 4 different types of simulations: N N N N Mobility simulations: We vary the essay india mobility to immigration paper, see how it affects the different metrics that we are measuring. Offered load simulations: We vary the load that we offer the value education india network, to english introduction, see how the protocols behave when for instance the load is high. Network size simulations: We vary the education number of violence essay, nodes in the network. Realistic simulations: A few realistic scenarios were designed.
These simulations do not give a general view of the protocol, but instead tests certain characteristics of the protocols. Essay India? Because we had different versions of both AODV and DSR we decided to first compare the vs. calling different versions of the same protocol. After that we did a more general comparison where we used one version of each protocol and compared them against value essay DSDV. The comparisons made are therefore: N N N Comparison of AODV with only practice dbq ap world history essay, hello messages, AODV with only link layer support and ADOV with both hello messages and education india link layer support. Comparison of memoir class thesis, DSR with and without eavesdropping. Comparison of DSDV, AODV with both hello messages and link layer support and DSR without eavesdropping. The reason for choosing DSR without eavesdropping in the last comparison, is as mentioned earlier that this is education, more realistic. Security features like encryption will prohibit eavesdropping in the future. The choice of memoir class thesis, AODV with both link layer support and hello messages was made because first of all, link layer support is probably a necessity to achieve a performance that is good enough and secondly because the value education essay india removal of hello messages somewhat changes the overall functionality of AODV. Removal of hello messages would of course save us from the overhead of the hello messages, but also makes the protocol completely on-demand. A broken link could only be detected when a packet needs to be sent on the link.
In all simulations, except the realistic scenario simulations, we have used a randomized scenario. The randomized scenarios have different parameters that affect the movement patterns. The parameters that can be changed are: N N N N N Maximum speed: Every time a speed is going to be randomized it is randomized in the interval [0,maximum speed]. Number of nodes: This was constant during the class thesis simulations. We used 50 nodes for all simulation except the size simulation where we varied the number of nodes.
Environment size: Determines the size of the environment. Education Essay? We have used a size of memoir class thesis, 1000 x 1000 meters for all simulations except the value essay realistic simulations where we have used 1500 x 900. Simulation time: The time for which the simulations will be run at. Ap Lang Analysis Essay? We have used a simulation time of 250 seconds for value education india all simulations except the realistic simulations where we used 900 seconds. English Essay Introduction? Pause time: Pause time is the time for education which a node stands still before randomizing a new destination and the speed that will be used to reach this destination.
We have used a pause time for 1 second in all simulations. The randomizing of scenarios works like this: first of all every node stands still for pause time seconds. After that each node selects a random destination, a waypoint somewhere in the environment space. Each node also randomizes a speed that will be used when moving to the waypoint. Texting Vs. Calling Essay? This speed is randomized uniformly in the interval 0 to essay, maximum speed. Language Essay Introduction? Every time a node reaches a waypoint, this procedure will be repeated. A factor that we have not taken into consideration with the scenarios is the fact that a real person is not likely to stand on the same place if the essay connection goes down. A real person is more likely to find a place where the cause and effect of domestic violence reception is good enough. The system would be to complex if this factor were included also. We have assumed bi-directional links during all our simulations, i.e. the education essay links work equally well in both directions.
It is questionable if unidirectional links are desirable when using the IEEE 802.11 MAC protocol, because bi-directional links are necessary if 802.11 acknowledgements are supposed to be used. 38 5.3 Mobility simulations 5.3.1 Setup The simulations where we varied the mobility where done by randomizing scenario files. This method is very hard to compare and contrast essay, perform, because we cannot prior a scenario generation say that we want a mobility factor of essay, exactly X. Instead we used the maximum speed parameter to control the scenario. The simulation parameters that have been used for the mobility simulations are shown in Table 7. Table 7: Parameters used during mobility simulations. English Essay Introduction? Parameter Transmitter range Bandwidth Simulation time Number of nodes Pause time Environment size Traffic type Packet rate Packet size Number of flows Value 250 m 2 Mbit 250 s 50 1s 1000x1000 m Constant Bit Rate 5 packets/s 64 byte 15 The scenario is value essay, a very crucial part of the simulation. We have therefore collected 10 measurements for each wanted mobility factor. The mobility factors that we simulated on are: 0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, and 3.5.
Because of the thesis hard part of getting scenarios that are precise we have used an interval of r0.1 for the above mentioned mobility factors. The scenarios that where created where then analyzed in terms of unreachable hosts. We did not want to investigate network partition at this stage, so all scenarios with extremely high degree of unreachable hosts where discarded. By increasing the maximum speed in the scenario generation, the mobility will also increase. A mobility factor of value education essay india, 3.5 approximately corresponds to a maximum speed of 20 m/s. Dbq Ap? For the randomized simulations we have varied the maximum speed in the interval 0 to 20 m/s. A speed of 20 m/s corresponds the speed of a vehicle, which will lead to a high mobility. We used the same communication pattern for all mobility simulations. Value Education Essay India? The traffic pattern consisted of cause and effect of domestic essay, 15 CBR sources that started at value essay, different times. We did not use TCP for essay introduction the simulations, because we did not want to investigate TCP, which uses flow control, retransmit features and so on. We wanted to education, get a general view of how the routing protocol behaves.
The communication pattern was randomly created. The parameters that was specified when randomizing the communication pattern were the number of wanted sources, the packet size, the rate at which they were sending and the simulation time. In these simulations, we wanted to investigate how the mobility affected the protocols, so the load that we offer is very low. We only use 15 CBR sources sending 64 bytes large packets with a rate of 5 packets/s. Violence Essay? The bandwidth of the links are 2 Mbit. 39 5.3.2 Fraction of received packets 0.8 Fraction received packets 1 0.8 Fraction received packets 1 0.6 0.4 0.2 0.6 0.4 0.2 AODV-HELLO-MAC AODV-MAC AODV-HELLO DSR-eaves dropping DSR 0 0 0 0.5 1 1.5 2 2.5 3 3.5 Mobility (m/s) 0 0.5 1 1.5 2 2.5 3 3.5 Mobility (m/s) 1 Fraction received packets 0.8 0.6 0.4 0.2 AODV-HELLO-MAC DSR DSDV 0 0 0.5 1 1.5 2 Mobility (m/s) Figure 13: 2.5 3 3.5 Mobility simulations - fraction of value essay, received packets. How many of the sent data packets are actually received and practice dbq ap world history why have the dropped packets been dropped?
Of the different AODV versions, it can been seen in value education, Figure 13 that both AODV versions that have MAClayer support are almost receiving all packets that are sent. AODV with both hello messages and dbq ap history essay MAC-layer support is slightly better than the version with only MAC-layer support. The reason for this is the same as mentioned earlier, the hello messages gets some prior knowledge of link breakages. AODV with only hello messages is however dropping a very large portion of the packets when the mobility increases. This large fraction of dropped packets is of course not acceptable and the reason for these drops has to do with the value education essay india interval of the hello messages. The interval between the hello messages and the number of allowed hello message losses are crucial for detection of link breakages. Cause Of Domestic Violence? If the interval is decreased, link breakages are detected earlier, but it would also mean that the value essay india control overhead in the network increases. The issue here is to texting vs. calling, try to education essay, find optimal values for these parameters. The choice of these parameters is also very dependent on the behavior that is desired; a higher fraction of received packets, a high throughput, low delay or a low overhead. The fraction of received packets for the DSR versions is very large even for high mobility.
The DSR version without eavesdropping has a slightly smaller fraction of received packets. This difference is however so small that it is negligible. Dbq Ap History Essay? DSR with eavesdropping gets better result for value the simple reason that it has a little more information when calculating the routes. A reason for compare texting the higher fraction received packets for DSR compared to AODV is that DSR allows packets to stay in the send buffer for value as long as 30 seconds, AODV only 8 seconds (our implementation). It must however be noted that the AODV draft  does not specify how long a packet is allowed to stay in cause and effect of domestic violence, the sendbuffer. When comparing these results with the results for DSDV it can clearly be seen that a proactive approach is value education india, not acceptable at all when the mobility increases. The fraction received packets drastically goes down to violence, 56-57 %. This value is however for a very large mobility factor (vehicles).
But the fraction of received packets is not even 100 % when the mobility is 0, as for all other protocols. The reason for value education this is that packets are sent before the routing tables have had enough time to converge and the packets are dropped. 40 The main reasons for dropping packets are that the english introduction protocol is sending packets on a broken route that it thinks is value india, valid and that packet in the buffers are dropped because of congestion and timeouts. At this low load we only have a small fraction of the packets that have been dropped because of collision. Immigration Paper? It can also be seen that IP-based hello messages as only link breakage detection mechanism is not a good idea. The results are very poor, even DSDV have slightly better results. Link layer feedback of value education essay, link breakages informs the upper layer routing protocol is much quicker and it can therefore react immediately. 5.3.3 End-to-end delay AODV-HELLO-MAC AODV-MAC AODV-HELLO 0.14 0.12 Avg packet delay (seconds) 0.12 Avg packet delay (seconds) DSR-eaves dropping DSR 0.14 0.1 0.08 0.06 0.1 0.08 0.06 0.04 0.04 0.02 0.02 0 0 0 0.5 1 1.5 2 2.5 3 3.5 2.5 3 0 0.5 1 1.5 2 Mobility (m/s) 2.5 3 3.5 3.5 Mobility (m/s) AODV-HELLO-MAC DSR DSDV 0.14 Avg packet delay (seconds) 0.12 0.1 0.08 0.06 0.04 0.02 0 0 0.5 1 1.5 2 Mobility (m/s) Figure 14: Mobility simulations - delay. Language Essay Introduction? As seen in Figure 14, of the value education essay different AODV versions AODV with only hello messages has lowest delay on the data packets that are received. The reason for this is and contrast texting vs. calling, not that it finds routes faster or that the routes are shorter or more optimal, instead AODV with only hello messages is the value education essay india AODV version that gets significantly fewest packets through the network. The packets that it successfully gets through the network have approximately the same low delay as for the other AODV versions.
The difference is that the other AODV versions have a portion of english introduction, packets that have a higher delay (has been in a buffer a long time and still gets the packets through the network). This affects the average delay, which becomes larger. Value Education India? In AODV with only practice dbq ap world history, hello messages, packets in the buffers that have been there for a long time are dropped. The reason is that ADOV does not successfully find a new route for those packets and because broken links are not detected fast enough, resulting in that a source can keep sending packets on a broken link believing that it is still working properly. AODV with both hello messages and MAC layer support has a slightly lower delay than AODV with only education, MAC-layer support. The reason for this is that as mentioned earlier, AODV with only MAC-layer support makes the protocol completely on-demand, it only detects link breakages when actually trying to send packets. Packets that are sent after this breakage is detected will have a higher delay, because they are buffered during the time it takes to find a new route.
AODV with both hello messages and Mac-layer support on the other hand will get some prior knowledge of the link breakage and has a chance to find a new route before any new packets are sent. 41 Both DSR versions show a tendency to get higher delay when mobility is increased. The turning point comes at a mobility factor of approximately 1.0. DSR without eavesdropping has a negligible higher delay compared to DSR with eavesdropping. DSDV is the world history protocol that seems to have lowest delay in these results. The results are however somewhat misleading because DSDV drops so many packets that it cannot said to be valid. The packets that are dropped in DSDV will successfully get through when using for instance DSR, but has a slightly higher delay, because of longer times in buffers etc.
These higher delay packets will make the education essay average delay higher for DSR. The same can be said for AODV with only memoir class thesis, hello messages. The other two AODV versions have a slightly higher delay than the DSR versions. This has probably to do with the source routing concept of value education essay india, DSR. DSR gains so much information by the source routes that it will learn routes to many more destinations than a distance vector protocol like AODV.
This will mean that while DSR already has a route for a certain destination, AODV would have to send a specific request for that destination. The packets would in the meanwhile stay in analysis essay, a buffer until a valid route is found. This will take some time and will therefore increase the average delay. In a packet based radio network without Quality of Service, the delays of the value india packets will vary much. The packets that do not have a route will be buffered until a route is found. Essay? A critical parameter here is how long a packet should be allowed to stay in the buffer before it is india, thrown away. If the packets are allowed to be in the buffer for a long time, the following situation could happen: A packet is sent, but there does not exist any route to that destination so the packet is buffered and memoir thesis a route request is sent. Value? The destination node is however unreachable so no route reply is returned to the sending node.
After a long time, the destination node suddenly becomes reachable and the packet is sent. Compare And Contrast Texting Vs. Calling? This packet will have a very large delay. Should this situation be allowed to happen? Should the packet be dropped from the buffer at a much earlier stage or do we want all packets to get through the network, even though the delay can be very large. In the case where we are using TCP, the retransmit operation will probably retransmit the value education essay packet at and effect violence, an earlier stage anyway, because no acknowledgement was received.
The allowed time for packets to stay in the sendbuffer in DSR is 30 seconds and only 8 seconds for AODV. If a packet is received 30 seconds after it was sent, this will increase the education essay india average delay to some degree. 5.3.4 End-to-end throughput 2.4 2.2 2.2 Throughput (Kbit/s) 2.6 2.4 Throughput (Kbit/s) 2.6 2 1.8 1.6 1.4 2 1.8 1.6 1.4 1.2 1.2 AODV-HELLO-MAC AODV-MAC AODV-HELLO DSR-eaves dropping DSR 1 1 0 0.5 1 1.5 2 2.5 3 3.5 Mobility (m/s) 0 0.5 1 1.5 Mobility (m/s) 2.6 2.4 Throughput (Kbit/s) 2.2 2 1.8 1.6 1.4 1.2 AODV-HELLO-MAC DSR DSDV 1 0 0.5 1 1.5 2 2.5 3 3.5 Mobility (m/s) Figure 15: Mobility simulations - throughput. 42 2 2.5 3 3.5 Figure 15 shows the throughput curves for the different protocols with a packet size of 64 bytes. Paper? It must however be mentioned that the curves in this case are only interesting from a relative view, as a comparison between the protocols. We have not tried to maximize the throughput, we have only tried to determine the relative difference in throughput for value india the different protocols with respect to class, the mobility factor and the specific load that we have used. The throughput curves for all protocols are very similar to the fraction received packet curves. This is logical because large packet drops will of india, course mean lower throughput. Both DSR versions and the AODV versions with link layer support have almost identical throughput. This throughput is also approximately constant, it decreases somewhat when mobility is as high as 2.5-3.5. AODV with only hello messages and DSDV have a throughput that drastically decreases when mobility increases.
AODV with only hello show a very poor result. The throughput curve drops almost immediately to half of what it is when mobility is outline, 0. 5.3.5 Overhead 25000 1.8e+06 AODV-HELLO-MAC AODV-MAC AODV-HELLO 20000 1.4e+06 Control overhead (bytes) Control overhead (packets) AODV-HELLO-MAC AODV-MAC AODV-HELLO 1.6e+06 15000 10000 1.2e+06 1e+06 800000 600000 400000 5000 200000 0 0 0 0.5 1 1.5 2 Mobility (m/s) 2.5 3 3.5 0 25000 0.5 1 1.5 2 Mobility (m/s) 2.5 3 3.5 1.5 2.5 3 3.5 2.5 3 3.5 1.8e+06 DSR-eaves dropping DSR DSR-eaves dropping DSR 1.6e+06 1.4e+06 Control overhead (bytes) Control overhead (packets) 20000 15000 10000 1.2e+06 1e+06 800000 600000 400000 5000 200000 0 0 0 0.5 1 1.5 2 2.5 3 3.5 0 0.5 1 Mobility (m/s) 25000 1.8e+06 AODV-HELLO-MAC DSR DSDV AODV-HELLO-MAC DSR DSDV 1.6e+06 20000 1.4e+06 Control overhead (bytes) Control overhead (packets) 2 Mobility (m/s) 15000 10000 1.2e+06 1e+06 800000 600000 400000 5000 200000 0 0 0 0.5 1 1.5 2 Mobility (m/s) 2.5 Figure 16: 3 3.5 0 0.5 1 1.5 2 Mobility (m/s) Mobility simulations - overhead. Because the routing protocol need to send control information to achieve the task of finding routes, it is interesting to education essay, see how much control information that is and contrast essay, actually sent for each protocol. There exists some sort of tradeoff between the byte overhead and the number of control information packets sent. A large byte 43 overhead would of course mean a larger part of wasted bandwidth. Many small control information packets would however mean that the radio medium on education essay india which packets are sent is cause and effect violence essay, acquired more frequently. This can be quite costly in terms of power and network utilization. The values that we have plotted do not include any physical layer framing or MAC layer overhead. India? We have only ap lang analysis prompt, looked at the overhead at the IP-level. A completely fair comparison would also include the above mentioned overheads. We have chosen not to include these for the simple reason that the education essay india MAC layer can be different in a real life implementation.
We wanted to investigate the overhead generally, not the overhead that is dependent on particularly the IEEE 802.11 MAC protocol. The results are shown in Figure 16. Memoir Thesis? The first column is overhead calculated in number of packets and value education essay india the second column is the byte overhead. The number of control packets and byte overhead is a total for all simulations done where we have varied mobility. Of the different AODV versions, it can be seen that the curves for the AODV versions that have link layer support are similar in appearance. Vs. Calling Essay? The difference of about 8000-9000 packets and 270000-290000 bytes that can be seen corresponds to the hello packets. Education India? The AODV version with only hello messages has a much more stable form of the curve. The small rise that is visible is the triggered route replies that are sent when a link goes down and the new requests that are sent to find a new route during route failures.
A route failure therefore triggers both triggered replies and new requests. This rise is and effect of domestic violence essay, much larger for the AODV versions with link layer support for the simple reason that it detects link failure much faster, which will lead to much more messages. DSR does not include the data packets in the number of india, control packet calculations, only the extra byte overhead from memoir these packets is included. Worth noting when observing the value DSR versions is compare vs. calling essay, that the value essay DSR version that does not use eavesdropping has approximately the illegal paper double amount of control overhead counted in number of value education india, messages and about 400000 bytes more of byte overhead than the DSR version with eavesdropping at the highest mobility 3.5. The somewhat strange behavior of the byte overhead for DSR can be explained as a sum of both the class thesis sent packets and the sent control messages.
As mobility increases, fewer packets will get through the network. Fewer packets mean less byte overhead in the source route of the packets. Increased mobility also means more topology changes, which will increase the number of update messages. The byte overhead is therefore decreasing and at approximately mobility 1.5 the value essay india increase of control messages will cause the byte overhead to increase. The number of control messages in DSDV is fairly constant, even when the mobility is extremely high. This is the nature of a proactive protocol that is dependent on for research paper periodic broadcasts. Essay? The byte overhead on the other hand, will increase as mobility increases. The reason for this is english essay introduction, that the amount of information sent in each update message will be larger as the amount of link changes increases. 5.3.6 Optimal path One internal aspect of the routing protocol is the routing accuracy, e.g. how good the actual routes are compared to the optimal routes. To illustrate this we have compared the actual hop count with the optimal shortest route for all received packets. Value Education? We have then, for each protocol, calculated how large fraction the analysis essay prompt received packets that have been routed through the optimal route, a route with hopcount that is education, one larger than the optimal, a route with hopcount that is two larger than the compare and contrast texting essay optimal and so on.
The result is shown in Table 8. Value Education India? The results are the total results for all simulations done with varying mobility. To better illustrate the difference between some of the protocols, we have also plotted the results for one AODV version, one DSR version and compared it with the only proactive protocol DSDV. Cause Essay? It can clearly be seen in Figure 17 that DSDV is the protocol that has the highest degree of optimality, almost 90 % of the received packets have been routed with optimal hop count. The AODV and DSR versions are almost identical. AODV is slightly better. This difference is however so small that it can neglected. The difference between the different DSR versions is essay, quite large and can be explained with the extra information that DSR with eavesdropping has when calculating routes. This extra information is apparently very informative when calculating shortest possible routes. AODV with only hello messages has best results of the different AODV versions. These due to the similarities with a proactive protocol like DSDV that is highly dependent on periodic broadcasts.
Because of the periodic updates DSDV needs some time before it converges to a steady state. Prompt? This happens when we have high movement with a lot of topology changes. Education India? Most of the dbq ap world history essay packets that are sent during this time are dropped and the rest of them get a little higher hopcount. All packets that are sent after the routing tables have converged to a steady state do however most likely have the optimal shortest path. AODV with only hello messages have a similar behavior. Link breakages are dependent on the hello messages. This will mean that high movement and frequent topology changes will lead to many packet 44 drops during this time.
The packet that successfully gets through the network have done this during times when the education network is somewhat stabile 1 AODV-HELLO-MAC DSR DSDV Packets (%) 0.8 0.6 0.4 0.2 0 0 2 Figure 17: 4 6 Nr of analysis, hops from optimal 8 10 Mobility simulations - optimal path difference. Because both DSR versions and the AODV versions with link layer support gets significantly more packets through the network when the value essay number of topology changes is large, they will have a little lower fraction of packets that have a optimal route. In times of frequent movement it is easy to get a route that at class thesis, first is optimal and value education india then the moment later is 1-2 hops longer than another route that become the optimal route. World History? The protocols will keep sending packets on the route that at first was optimal. Value India? A good relative comparison is to look at the average hop count difference for all packets received. Language? DSDV has the education smallest average with a hopcount at only 0.13 hops from the optimal path. Table 8: Protocol AODV 1 AODV 2 AODV 3 DSR 1 DSR 2 DSDV 0 79.1% 55.9% 68.4% 81.1% 63.2% 88.7% Optimal path difference for all protocols.
Number of hops from optimal path (% packets) 1 2 3 4 5 6 14.8% 3.68% 1.08% 0.30% 0.55% 0.06% 29.9% 9.04% 2.62% 1.09% 0.56% 0.20% 23.0% 5.37% 1.48% 0.84% 0.47% 0.14% 15.3% 2.73% 0.54% 0.13% 0.08% 0.01% 26.6% 7.21% 2.21% 0.56% 0.13% 0.05% 10.6% 0.59% 0.06% 0.00% 0.00% 0.00% 45 7 0.06% 0.38% 0.04% 0.02% 0.03% 0.00% Average 0.292170 0.682837 0.459423 0.234429 0.512004 0.126577 5.3.7 Summary mobility simulations The protocols that have link layer support for link breakage detection will be much more stable. The fraction of packets received for these protocols is almost constant at 95 % even when mobility increases. This result indicates that these kinds of texting vs. calling, protocols will get the job done even when mobility increases. These protocols include both DSR versions and the two AODV versions that have this link layer support. Protocols that are highly dependent on periodic broadcast show a rather poor result, only education essay india, little more than 50 % of the packet are received when mobility is illegal for research paper, increased. Value Essay? Because DSR is a source routing protocol it is always interesting to see how much overhead this kind of protocol will have. The byte overhead is larger than for instance the AODV version that uses both hello messages and link layer support for link breakage detection. Illegal Immigration Outline For Research? The interesting thing with this is that the number of control messages is much smaller for DSR than any other protocol. This is interesting because this means that an approach that uses a source routing based approach to find routes combined with a destination vector approach for sending data packets could be desirable. 5.4 Offered load simulations We have used these protocols for these simulations: N N N AODV with both hello messages and MAC link layer support. DSR without eavesdropping DSDV We only used the more realistic version of both AODV and education essay india DSR, for the same reason as mentioned in the previous section.
5.4.1 Setup The offered load simulations where done by varying the load that we offer the network. Illegal Immigration Outline Paper? We had mainly three parameters to adjust the offered load: N N N Packet size Number of CBR flows Rate at which the flows are sending The mobility simulations that we have done used a packet size of 64 bytes, a rate of 5 packets/s and education 15 CBR flows. This is a fairly moderate offered load, so for the offered load simulations, we wanted to for research paper, investigate how the protocols behave when the load was increased. Value Education India? We could increase the cause and effect packet size or the education number of class thesis, CBR flows, but the parameter that best describes the value essay india load is the rate at which we are sending. By only increasing the class rate for the CBR flows, the load for each flow will increase. This also gives some hints of how large the throughput can be. Education Essay India? We have used four different offered load cases: N N N N 5 packets / second (same as the mobility simulations) 10 packets / second 15 packets / second 20 packets / second The packet size was held constant at 64 bytes and the number of ap lang analysis essay, flows at 15.
We used the same randomized scenario files as in the mobility simulations. Education Essay India? The same communication file was also used, with the exception that we changed the rate for immigration paper the CBR sources. Value Education? The parameters that we used during the practice dbq ap world history essay offered load simulation are shown in Table 9. 46 Table 9: Parameters used during offered load simulations. Parameter Transmitter range Bandwidth Simulation time Number of nodes Pause time Environment size Traffic type Packet rate Packet size Number of flows Value 250 m 2 Mbit 250 s 50 1s 1000x1000 m Constant Bit Rate 5 packets/s 64 byte 15 5.4.2 Fraction of received packets 0.8 Fraction received packets 1 0.8 Fraction received packets 1 0.6 0.4 0.2 0.6 0.4 0.2 AODV 5 pkt/s AODV 10 pkt/s AODV 15 pkt/s AODV 20 pkt/s DSR 5 pkt/s DSR 10 pkt/s DSR 15 pkt/s DSR 20 pkt/s 0 0 0 0.5 1 1.5 2 Mobility (m/s) 2.5 3 3.5 1 1.5 2 Mobility (m/s) 2.5 3 3.5 0 0.5 1 1.5 2 Mobility (m/s) 2.5 3 3.5 1 Fraction received packets 0.8 0.6 0.4 0.2 DSDV 5 pkt/s DSDV 10 pkt/s DSDV 15 pkt/s DSDV 20 pkt/s 0 0 0.5 Figure 18: Offered load simulations - fraction of received packets. At only 5 packets/s both AODV and DSR are rather constant, the fraction of received packets is value, only decreasing slightly when mobility increases (Figure 18). At 10 packet/s we can see that the fraction received packets is decreasing much faster when the mobility factor is cause of domestic, greater than 2. At 15 packets/s and 20 packets/s both AODV and DSR are dropping a large fraction of the packets. At the highest mobility and a rate of essay india, 20 packets/s, only 50-60 % of the sent packets are received. The reason is more collisions in the air and memoir class congestion in buffers.
The results for AODV and DSR are fairly similar at a packet rate of 5 packets/s and 10 packets/s. At data rates of 15 packets/s and india 20 packets/s, AODV shows a better result than DSR. At these rates the protocols are however dropping a large fraction of the packets, even at class thesis, a mobility factor of 0. DSR will have a much larger byte overhead than AODV at higher data rates (Figure 21). The reason for this is the source route in each data packet. This also increases the load on education india the network and causes more packets to be dropped; thus AODV will get more packets through the network.
47 DSDV is dropping a large fraction of the packets already at essay, the lowest data rate 5 packets/s. It must however be noted that the increase in dropped packets is not as large for value DSDV as for AODV and compare texting essay DSR. At the highest data rate, DSDV is education india, almost as good as DSR. 5.4.3 End-to-end delay 0.7 0.7 AODV 5 pkt/s AODV 10 pkt/s AODV 15 pkt/s AODV 20 pkt/s 0.6 0.5 Avg packet delay (seconds) Avg packet delay (seconds) 0.6 DSR 5 pkt/s DSR 10 pkt/s DSR 15 pkt/s DSR 20 pkt/s 0.4 0.3 0.5 0.4 0.3 0.2 0.2 0.1 0.1 0 0 0 0.5 1 1.5 2 2.5 3 3.5 0 0.5 1 1.5 2 2.5 3 3.5 Mobility (m/s) Mobility (m/s) 0.7 DSDV 5 pkt/s DSDV 10 pkt/s DSDV 15 pkt/s DSDV 20 pkt/s Avg packet delay (seconds) 0.6 0.5 0.4 0.3 0.2 0.1 0 0 0.5 1 1.5 2 2.5 3 3.5 Mobility (m/s) Figure 19: Offered load simulations - average delay. The delay is also affected by high rate of CBR packets (Figure 19). The buffers becomes full much quicker, so the packets have to stay in the buffers a much longer period of time before they are sent. This can clearly be seen at the highest rate 20 packets/s. The high degree of packet drops, even at mobility 0 makes the delay high already from the start.
DSR has a much lower delay compared to AODV. The difference between AODV and DSR is most apparent at memoir thesis, rate 10 packets/s. Education Essay? DSDV has the class thesis lowest delay of them all. This is however an education essay india, effect from the large fraction of packet drops that DSDV has, compared to DSR and AODV. The increase in delay for cause DSDV also comes from the increased time that the packets must stay in the buffers. The high delay at a mobility factor of 0-1 and a data rate of 20 packets/s that can be seen for education all protocols is a result of the extremely high data rate and the low mobility. The high data rate will fill up the buffers very quickly. And Effect Essay? The low mobility will mean that already found routes are valid for education india a much longer time period. This means that found routes can be used for more packets.
Even the packets that have stayed in the buffer for a long time have a chance to get through. When mobility increases, more routes will become invalid and illegal new requests are necessary. While the education requests are propagating the network in search for immigration outline for research a new route, buffers will get full and packets are dropped. These packets are the education essay packets that have stayed in the buffers for the longest time and therefore the delay will decrease. The increase in language introduction, mobility actually results in a load balancing of the traffic between the nodes; hot spots are “removed” due to mobility. Value Education Essay India? For DSDV, the average delay at highest data rate will actually be lower than at the rate of 15 packets/s. Practice Dbq Ap History Essay? This is a little strange but has probably something to do with the fact that DSDV only value essay, uses a buffer that only has room for 5 packets per flow.
At the rate of 15 packets/s and 20 packets/s, when mobility starts to get so high that the topology changes frequently, only and effect essay, 40-60 % of the packets gets through the network. These 48 topology changes means that the protocol needs more time to converge before the india packets can be sent. The buffers will therefore be congested almost all the time so the packets that actually get through have approximately the same the compare texting vs. calling essay delay. 5.4.4 End-to-end throughput 8 8 6 Throughput (Kbit/s) 7 6 Throughput (Kbit/s) 7 5 4 3 5 4 3 2 2 AODV 5 pkt/s AODV 10 pkt/s AODV 15 pkt/s AODV 20 pkt/s 1 0 0 0 0.5 DSR 5 pkt/s DSR 10 pkt/s DSR 15 pkt/s DSR 20 pkt/s 1 1 1.5 2 Mobility (m/s) 2.5 1.5 2.5 3 3.5 0 0.5 1 1.5 2 2.5 3 3.5 Mobility (m/s) 8 7 Throughput (Kbit/s) 6 5 4 3 2 DSDV 5 pkt/s DSDV 10 pkt/s DSDV 15 pkt/s DSDV 20 pkt/s 1 0 0 0.5 1 2 3 3.5 Mobility (m/s) Figure 20: Offered load simulations - average throughput. At low CBR rates the throughput of india, DSR and AODV is unaffected of the mobility (Figure 20), it stays constant at 2,5 Kbit/s. At higher CBR rates, the class throughput will decrease when the mobility increases. This can already be seen at CBR rate 10 packet/s.
The decrease at CBR rate 10 packets/s is however very small. Essay? At rate 15 packets/s and 20 packets/s the throughput decreases very much for all protocols. Compare And Contrast Vs. Calling? This is however an effect from the large fraction of india, dropped packets. The result for AODV is dbq ap history, slightly better than for DSR. It must however be noted that the offered load definition that we use only includes the rate at which we are sending packets with; no control packets are included in this definition. The same applies for the throughput, only the data packets are included in the calculations of throughput. DSR have a much larger byte overhead than AODV at higher data rates (Figure 21). This also increases the load on the network and causes more packets to be dropped; thus AODV will have a better throughput at higher data rate.
DSDV drops a large fraction of the packets already at essay india, a rate of 5 packets/s. This can be seen in the small decrease in the throughput at rate 5 packets/s. The throughput decreases more and more as the rate increases. 5.4.5 Overhead In Figure 21, the difference between distance vector and source routing can clearly be seen. The byte overhead for analysis DSR is much larger than AODV even at low data rates and the difference becomes larger when the value CBR rate increases. At CBR rate 20 packets/s, the byte overhead for DSR is more than the world history essay double than for essay AODV. The reason for the larger byte overhead for DSR is of course the source route in each packet. The 49 number of control messages is though smaller for DSR. Essay? This is the other characteristic for value education india source routing, it learns all routes in ap lang analysis essay prompt, the source route and education essay india therefore does not need to send as many route requests. The reason for the increase in number of world, control packets is the MAC-layer support. The increase in value education essay india, rate means that the MAC-layer will detects link failures much faster.
This means that the triggered RREPs are sent much earlier also causing the source node to class, send out a new request much earlier. All link failures are detected earlier with increased rate; thus there will be time for more RREQs, RREPs and triggered RREPs. 4e+06 35000 AODV 5 pkt/s AODV 10 pkt/s AODV 15 pkt/s AODV 20 pkt/s 30000 AODV 5 pkt/s AODV 10 pkt/s AODV 15 pkt/s AODV 20 pkt/s 3.5e+06 3e+06 Control overhead (bytes) Control overhead (packets) 25000 20000 15000 10000 2.5e+06 2e+06 1.5e+06 1e+06 5000 500000 0 0 0 0.5 1 1.5 2 Mobility (m/s) 2.5 3 0 3.5 0.5 1 1.5 2 2.5 3 3.5 Mobility (m/s) 35000 DSR 5 pkt/s DSR 10 pkt/s DSR 15 pkt/s DSR 20 pkt/s 30000 4e+06 3e+06 Control overhead (bytes) 25000 Control overhead (packets) DSR 5 pkt/s DSR 10 pkt/s DSR 15 pkt/s DSR 20 pkt/s 3.5e+06 20000 15000 2.5e+06 2e+06 1.5e+06 10000 1e+06 5000 500000 0 0 0.5 1 1.5 2 2.5 3 0 3.5 0 0.5 1 Mobility (m/s) 1.5 2 2.5 3 3.5 Mobility (m/s) 4e+06 DSDV 5 pkt/s DSDV 10 pkt/s DSDV 15 pkt/s DSDV 20 pkt/s 35000 DSDV 5 pkt/s DSDV 10 pkt/s DSDV 15 pkt/s DSDV 20 pkt/s 30000 3.5e+06 3e+06 Control overhead (bytes) Control overhead (packets) 25000 20000 15000 10000 2.5e+06 2e+06 1.5e+06 1e+06 5000 500000 0 0 0 0.5 1 1.5 2 Mobility (m/s) 2.5 Figure 21: 3 0 3.5 0.5 1 1.5 2 2.5 3 3.5 Mobility (m/s) Offered load simulations - overhead. The amount of control information in DSDV is value education india, not affected to thesis, any great extent by the data rate for the CBR packets. Education India? By looking at Figure 21 it looks like the number of control packets is exactly the same for all data rates, but there is actually a small difference. The number of control packets is illegal immigration outline, actually a little smaller when the rate is 20 packets/s. This difference is education essay, about 80 packets.
The reason for this difference is that the high data rate causes more collisions, which means that some of the update messages are dropped. These lost update messages will not be received by practice history, any node, and cannot therefore trigger new update messages. This means that when the next update message actually is received a much larger update message has to be sent, thus we can see a slight increase of byte overhead when the rate increases. Value Essay India? But when the mobility increases more and more packets will be dropped. At the highest data rate, many of the update messages are dropped, 50 even the packets with a little more information. This causes the byte overhead for DSDV at higher data rates not to increase to world history, the same extent as for DSDV with lower data rates. 5.4.6 Optimal path Figure 22 illustrates the difference in hopcount from the optimal hopcount at a CBR rate of education essay india, 20 packets/s. It is the result for all simulations done at this rate. If we compare this figure with Figure 17, which illustrates the compare and contrast essay hopcount difference for the CBR rate 5 packets/s, we can clearly see that they are almost identical.
The rate does not affect the number of hops that the packets actually need to travel from source to education india, destination. 1 AODV 20 pkt/s DSR 20 pkt/s DSDV 20 pkt/s Packets (%) 0.8 0.6 0.4 0.2 0 0 2 Figure 22: 4 6 Nr of hops from optimal 8 10 Offered load simulations – optimal path. 5.4.7 Summary offered load simulations The performance of the protocols differs slightly during different network loads. The most apparent difference is the byte overhead. While DSDV has a rather unaffected overhead, it increases both for AODV and DSR during higher loads.
A higher sending rate causes the protocol to detect broken links faster, thus reacting faster. This leads to a slight increase in control packets, which also affects the byte overhead. The most apparent is the increase in DSRs overhead as we increase the send rate. Since each data packet contains a source route, the dbq ap world history byte overhead increases dramatically. The increased send rate also set demands on the send buffer of the routing protocol.
Congestion occurs and value packets are dropped. The faster a routing protocol can find a route, the less time the packets have to spend in buffers, meaning a smaller probability of packet drops. 51 5.5 Network size simulations We did simulations on some of the protocols and varied the number of nodes that participated in practice dbq ap world history essay, the network. Essay India? We decreased the number of nodes to 35 and 25 nodes. The decrease in number of nodes basically meant that the connectivity also decreased; each node had fewer neighbors.
The results from practice dbq ap world essay these simulations did not give any new information regarding the performance of the protocols. Education India? The relative difference between the protocols was the same. Decreased connectivity meant of course that we did not get as many packets through the network as in the mobility simulations, but it must however be noted that the practice dbq ap world dependency between the scenarios and results are much larger in the network size simulations. The worst results for each protocol happened when the mobility was 0. This may sound strange, but the reason for the bad result when the nodes is education, standing still is the randomized scenarios. If a randomized scenario has poor connectivity, this connectivity will be same during the whole simulation if the nodes are standing still. World History? The nodes are not moving and cannot therefore affect the essay connectivity. In a scenario with moving nodes however, the connectivity will vary during the whole simulation. So even if a node is unreachable from the beginning, there is still a chance that it will be reachable some time later. Language Essay? 5.6 Realistic scenarios 5.6.1 Setup The randomized simulations we have done, gives a very good general picture of how the protocols behaves in value education essay india, respect to certain parameters, such as mobility, size and world essay network load. This kind of simulations also has some problems: N N N It is hard to identify situations in which the protocols fail or have problems It has no connection to value, a real life situation. It may favor complex protocols, while in real life scenarios simpler protocols can find the routes almost as effectively.
It is therefore also very interesting to cause and effect, see how the protocols behave in value education india, a more realistic scenario. We have therefore done simulations on some scenarios believed to be realistic. Illegal Outline Paper? The realistic scenarios do not give a full picture of india, how the protocols behave generally. Instead they give some sense of history, weak points in the protocols. The three basic types of scenarios that we have done simulations on are: N N N Conference type, with low movement factor.
Event coverage type, with fairly large movement factor. Could for essay india instance be reporters trying to interview politicians. Disaster area, with some relatively slow nodes and some very fast nodes (mounted on a car or a helicopter). The environment size is 1500 x 900 meters for all realistic scenarios. This size is scaled according to the range of the english introduction transmitters. In a real life conference scenario, the essay environment size would be significantly smaller and so would also the transmitter range.
The same thing would apply for cause violence the speed of the education essay india people moving around. The speed is also scaled to practice history, 10 m/s. All parameters used during the essay realistic simulations are shown in Table 10. 52 Table 10: Parameters used during realistic simulations. Parameter Transmitter range Bandwidth Simulation time Number of nodes Environment size Traffic type Packet rate Packet size Speed of a human Speed of language essay, a mobile node mounted on a vehicle Value 250 m 2 Mbit 900 s 50 1500x900 m Constant Bit Rate 4 packets/s 512 byte 1 m/s 20 m/s 5.6.2 Conference This scenario simulates 50 people that are attending a conference, seminar session or some similar activity. It involves communication between some of the value essay india people. Parameters specific for the conference scenario are shown in Table 11 Table 11: Parameters used during conference scenario.
Parameter Number of CBR sources Number of receivers Number of flows Value 2 6 6 The scenario is characterized by: N N N N N Low mobility factor, 10 % of the nodes are moving during any period of time. Paper? Links are long lasting and value involves many hops. Class? The traffic is concentrated to a few nodes, typically only the speaker. Few obstacles which are far apart. Typically only one large obstacle, a wall with doors and windows that can be used for communication. Relatively large interference from value essay india other nodes, due to the concentration of transmitting nodes. This can in some cases lead to local congestion. The scenario basically tests the protocols: N N N Ability to history, respond to local changes for long links. Ability to education india, cope with large concentration of traffic.
Message overhead with low mobility factor. Figure 23 shows how the scenario was designed and created with ad-hockey. The scenario is divided into and contrast texting, three zones that have their certain characteristics. Education? N N N Zone 1 - Speaker zone: The speaker moves back and english introduction forth. This changes the value closest neighbor in history essay, the audience.
Zone 2 - Audience zone: Static audience that is value education essay, sitting still most of the memoir class time. Very seldom does a node go outside to return a certain amount of time later. This will probably result in essay, a link breakage of english language, a longlasting link. Essay? Zone 3 - Outsider zone: Outsiders behind a wall that are trying to establish a connection between the speaker and each other. 53 Transmitter range Zone 1 Zone 2 Zone 3 = Node = Obstacle = Movement Figure 23: Conference scenario. The results for this scenario are shown in Table 12 and illegal immigration outline for research paper Table 13.
It must however be noted that we do not distinguish the results for education essay india nodes that are in zone 2 or zone 3. Illegal For Research Paper? The calculated mobility factor for this scenario is very low. Education India? All protocols except DSDV and the AODV version that only uses hello messages show quite good performance, delivering between 92-99% of the language essay introduction packets with an essay, average throughput between 14.8 – 15.7 Kbit/s. Compare And Contrast Texting? DSDV delivers only education india, 75.6% of the packets with an language, average throughput of 12.1 Kbit/s and the AODV version with only hello messages delivers 89.3 % of the packets, with a throughput of 14.3 Kbit/s. This shows that an ad-hoc routing protocol must quickly adapt to link changes even for long lasting routes as in this case where mobility is very low. Table 12: Mobility factor Received Throughput Sent Average delay Dropped Received packets Packet overhead Byte overhead Average hopcount DSDV 0.0439350 75.6% 12.1 Kbit/s 21510 0.052 s 5250 16260 44054 6406036 5.32 Conference simulation results. DSR - 1 0.0439350 97.1% 15.55 Kbit/s 21510 0.210 s 614 20896 3129 3689865 5.73 DSR - 2 0.0439350 98.0% 15.7 Kbit/s 21510 0.23 s 422 21088 4109 4093220 5.79 54 AODV - 1 0.0439350 89.3% 14.30 Kbit/s 21510 0.26 s 2298 19212 43881 1660020 6.62 AODV - 2 0.0439350 92.3% 14.79 Kbit/s 21510 0.29 s 1644 19866 14537 610884 6.53 AODV - 3 0.0439350 94.0% 15.00 Kbit/s 21510 0.39 s 1376 20134 54677 2112716 6.45 Both versions of DSR have the india lowest packet overhead in this scenario, while all versions of AODV show the lowest byte overhead. Analysis Essay Prompt? The large byte overhead for value essay DSR has to do with the for research fairly large amount of traffic and that the routes have an average hopcount that is as large as 5-6 hops.
As can be seen in Table 13. DSDV fails to education essay, deliver 3599 packets because of route failures. This is due to the slow response time when links go down and the time it takes to essay prompt, find new routes. A lot of packets will be sent using a route that the protocol thinks is valid, while in education india, fact the illegal immigration paper route is broken and the packets are dropped. Also a lot of packets are dropped in the interface queue. AODV using only hello messages show the same tendency, dropping 1364 packets because of the same reasons. Essay India? It is however fewer packets than for analysis DSDV. This has to do with the time between the HELLO messages. The less time between the messages, the faster can the education protocol react to broken links and avoid dropping the packets. In general, most of the cause violence packets are dropped in the sendbuffer. Retransmission of these dropped packets could of course be handled by upper layer protocols, such as TCP.
Table 13: Cause for education india drop Sendbuffer Route failures ARP Interface queue End of simulation DSDV 3599 74 1567 10 Packet drops in conference scenario. English Language Essay? DSR – 1 519 30 34 18 13 DSR – 2 303 98 4 0 17 AODV –1 894 1348 22 4 30 AODV – 2 1364 201 21 10 48 AODV -3 1096 202 14 0 64 5.6.3 Event coverage This scenario simulates a group of value education essay india, 50 highly mobile people that are changing position quite frequently. It could for instance represent a group of reporters that are covering a political event, music concert or a sport contest. In real life it would be nearly impossible to establish a wired network between the reporters, but they must be in constant communication with each other, enabling a fast reaction. Parameters that are specific for the event coverage scenario are shown in Table 14. Table 14: Parameters used during event coverage scenario. Parameter Number of CBR sources Number of english language introduction, receivers Number of flows Value 9 45 45 The scenario is characterized by: N N N N N Rather high mobility factor. Value Education Essay? Typically 50 % of the nodes are constantly changing their position during any time of immigration outline, period.
Every now and then the value education essay india nodes tend to cluster. Links involve a few hops and relatively short-lasting. Traffic is spread all over the place. Many obstacles. Nodes can usually only communicate with a few nodes. This will lead to a low interference from the other nodes, except for the moments of ap lang essay, clustering. Value India? 55 The scenario tests the protocols: N N Ability to respond to fast link changes and fluctuating traffic. Message overhead with constant topology updates. Figure 24 shows how the scenario was designed. 50 % of the nodes are moving randomly with a constant speed of 1 m/s. Every now and essay then a temporary cluster contain approximately 10 nodes will form.
These clusters remain static for a certain amount of time. Temporary clusters = Node = Obstacle Figure 24: = Movement Event coverage scenario. The results for the event coverage scenario are shown in Table 15 and Table 16. As Table 15 shows, the two protocols that has the lowest fraction of packets received are DSDV and the AODV version that entirely relies on feedback from link-layer. These protocols only have a fraction of packets received that lies around 91-92 %. For all other protocols/versions this value is at least 94 %. The mobility factor for the scenario is value essay india, 0.72, which is quite low even though considering we have about 50 % of the nodes in movement. The nodes are however only moving with a speed of 1 m/s. Cause Violence? DSDV has the highest overhead of all the protocols, counted in both number of control packets and bytes. DSR both with and without eavesdropping have a very low overhead. It must however be noted that the education essay india traffic load in this scenario is very low and most of the practice dbq ap world communication is value education india, taking place in a very small area, thus leading to a very low average hopcount of ap lang analysis prompt, approximately 1.5 for all protocols. In this scenario, AODV with only hello message shows better results than AODV with only link-layer support and the reason is that the education india hello messages makes it possible to keep track of compare and contrast texting vs. calling essay, neighbors. Education Essay? Most of the communication is taking place within clusters, so to know the neighbors will probably mean that we will not have to make as many requests.
The topology of the network is changing quite frequently. This causes a protocol like DSDV to practice dbq ap world history, have a very large overhead. Value Education? The communication however, take mostly place within the clusters. This makes the job for the on-demand-based protocols much easier. The hopcount from source to practice dbq ap world history, destination is value essay india, very small so the protocols will find a route very quickly. The protocols which are entirely on-demand will have a slightly 56 higher delay and the protocols that uses some sort of vs. calling essay, periodic messages (DSDV and the ADOV version that use hello messages) will have lower delay.
Table 15: Mobility factor Received Throughput Sent Average delay Dropped Received packets Packet overhead Byte overhead Average hopcount DSDV 0.721611 91.4% 14.75 Kbit/s 4500 0.075 s 385 4115 42415 10578764 1.46 hops Event coverage simulation results. DSR – 1 0.721611 97.5% 15.68 Kbit/s 4500 0.138 s 111 4389 1056 141196 1.53 hops DSR – 2 0.721611 97.7% 15.71 Kbit/s 4500 0.140 s 102 4398 1354 158420 1.57 hops AODV – 1 0.721611 94.5% 15.33 Kbit/s 4500 0.024 s 245 4255 31342 1137752 1.55 hops AODV – 2 0.721611 92.2% 14.89 Kbit/s 4500 0.214 s 352 4148 2722 117904 1.75 hops AODV – 3 0.721611 95.1% 15.36 Kbit/s 4500 0.015 s 219 4281 31443 1142180 1,55 hops Table 16 shows that most of the packets are dropped due to route failures and in those cases where there exists a sendbuffer, congestion/time-out in the sendbuffer. AODV that only uses link-layer support (AODV 2) has most of the essay india dropped packets due to failed ARP requests and essay DSDV drops most of value india, its packets at the interface queue. Table 16: Cause for drop Sendbuffer Route failures ARP Interface queue End of simulation DSDV Packet drops in compare vs. calling, event coverage scenario. DSR - 2 81 19 1 AODV - 1 100 83 61 1 102 48 235 DSR – 1 81 21 9 9 AODV - 2 131 32 178 10 1 AODV - 3 100 15 104 5.6.4 Disaster area This scenario represents some sort of disaster area in essay india, a region that lacks any sort of language introduction, telecommunication infrastructure. It could for instance represent a natural disaster or a large rescue operation. Every rescue team member could have a personal communicator with ad-hoc network capability. These personal communicators are capable of communicating with each other and with relay nodes that are mounted on a vehicle, like a helicopter, car or boat.
The parameters that are specific for india the disaster area scenario are shown in cause and effect of domestic violence essay, Table 17. Essay India? Table 17: Parameters used during disaster area scenario. Parameter Number of CBR sources Number of receivers Number of flows 57 Value 38 87 87 The scenario is characterized by: N N N N N N A node movement, where approximately 95 % of the nodes are moving slightly, while the remaining 5 % are changing their position very often. Network partitioning now and memoir class thesis then. Long and short lasting links that only are a few hops.
Traffic that is spread all over the nodes. Value Essay India? Many obstacles. Low interference from the dbq ap other nodes. Education India? The scenario tests the protocol: N N Ability to work with both slow and fast changing network topologies. Memoir Thesis? Ability to education india, cope with network partitioning. Figure 25 shows how the scenario was designed. There are two highly mobile nodes moving at the speed 20 m/s back and forth. There are also three separate subnetworks that can connect to each other through the relays mounted on the highly mobile nodes. Dbq Ap World History? Within each subnetwork, the movement is randomized at education essay, speed 1 m/s.
Subnetwork 2 Subnetwork 1 Vehicle 1 = Node Subnetwork 3 = Obstacle Figure 25: Vehicle 2 = Movement Disaster area scenario. The results for the disaster area scenario are shown in Table 18 and Table 19. The calculated mobility factor for this scenario is quite high. Practice? Many of the nodes are moving slightly (people), and india some nodes are moving very fast (vehicles). The protocols that show the best results in this scenario are the ap lang analysis purely reactive approaches, that is AODV using both hello messages and MAC support and DSR with eavesdropping. They have a delivery ratio between 54–58 % of the education essay india packets with an average throughput of 14.1 – 14.8 Kbit/s. DSDV has the cause of domestic violence worst performance, delivering only 29,5% of the packets with an average throughput of value essay, 12.42 Kbit/s. A delivery ratio of only paper, 58 % for value education essay the best protocol may sound like a terrible ratio, but because of network partitioning, it is hard for any protocol to successfully deliver more packets than that. 58 DSDV show the lowest delay, but this is due to the low delivery ratio. All versions of AODV keep an average delay between 0.89 – 1.05 seconds, while the DSR versions lie between 1.19 – 1.25 seconds. Both DSR versions keep a low packet overhead compared to the other protocols.
The byte overhead is however twice as large for DSR compared to AODV. As expected, DSDV uses the shortest paths with an average of 3.42 hops. Cause And Effect? The other protocols has an average hopcount of 5.0-5.2 hops. Value Education? Table 18: Mobility factor Received Throughput Sent Average delay Dropped Received packets Packet overhead Byte overhead Average hopcount DSDV 1.154619 29.5% 12.42 Kbit/s 29616 0.196 s 20867 8749 41402 6497476 3.42 hops Disaster area simulation results. DSR – 1 1.154619 58.0% 14.79 Kbit/s 29616 1.252 s 12440 17176 27048 4880992 5.01 hops DSR – 2 1.154619 54.50% 14.43 Kbit/s 29616 1.187s 13464 16152 30692 5137148 5.16 hops AODV – 1 1.154619 48.0% 13.07 Kbit/s 29616 0.888 s 15382 14234 61557 2426164 5.23 hops AODV – 2 1.154619 52.2% 13.49 Kbit/s 29616 1.052 s 14161 15455 50686 2426164 5.24 hops AODV – 3 1.154619 54.0% 14.09 Kbit/s 29616 0.988 s 13635 15981 77311 3096228 5.26 hops DSDV drops a lot of packets because of practice world essay, route failures. In this scenario, DSDV also drops a large amount of packets in the interface queue.
One large cause for drops in the other protocols, lies in the sendbuffer. If routes are not found within time, packets in the buffer are dropped because of timeouts or congestion. Another large cause for packet drops is route failures. This scenario is very interesting and should be investigated further, especially for the AODV protocol. We discovered when running the value education simulations that AODV tend to form short lived routing loops. Since the author claim that this protocol should be loop free at english essay introduction, all times, one possible cause for this might be invalid use of the value essay india sequence numbers or the of domestic essay fact that sequence numbers are unsynchronized during network partitioning. Very few packets were dropped because of this (less than 5). Another interesting thing with this scenario is value essay, that all main nodes send traffic both ways to each other.
This causes AODV to respond to and contrast vs. calling essay, requests with temporary routes set up by other requests. Since it is education essay india, unclear from the draft whether the temporary routes should be regarded as a normal route in language, the routing table or not, we decided to try both in this scenario. By only allowing RREPs to use the temporary routes, and by value, not allowing a node to respond to a RREQ with a temporary route, the routing loops could be avoided. Prompt? However, the performance of the protocol decreased. Value Education India? We therefore used simulations where we considered the temporary routes as a normal route.
Table 19: Cause for drop Sendbuffer Route failures ARP Interface queue End of simulation DSDV 15853 479 4528 7 DSR – 1 10033 1990 35 3 1 Packet drops in english essay, disaster area. DSR - 2 10277 2960 64 159 9 59 AODV – 1 9836 5047 292 34 2 AODV - 2 10693 3046 241 20 1 AODV - 3 10941 2470 64 44 116 5.6.5 Summary realistic scenarios The realistic scenarios show how the protocols behave in certain situations. Education India? For this purpose, three scenarios were designed and simulated with different versions of the protocols DSDV, DSR and AODV. DSR show the best performance results overall. Memoir? If source routing is undesirable, another good candidate is value education india, AODV with only MAC layer support.
It has a slightly higher packet overhead, but an and effect violence, overall good delivery ratio. 5.7 Observations The protocols that we have worked with most are AODV and DSR, thus we have observed some important differences for these protocols, that in some way affect the performance of the protocols. 5.7.1 Ability to find routes AODV To illustrate AODVs ability to find routes, we use a simple scenario (see Figure 26). The scenario consists of four nodes A, B, C and D connected to each other. A C D B Figure 26: Simple example scenario. Node A needs a route to education essay, node D. No data has been sent earlier, thus the only routes known to the AODV protocol are the different neighbors in the scenario. This is illegal for research, because AODV uses hello messages to keep track of the neighbors of a node. A RREQ is generated by node A and broadcasted to its neighbors. The RREQ propagates through the network until it reaches node C. Since node C has a route to node D it can comply with the RREQ and generate a RREP.
During the propagation of the RREQ, a reverse path is set up to node A. The RREP is unicasted back to A. It uses the temporarily backward route set up by the RREQ. During the propagation of the reply, a forward route is set up to node D by education, all intermediate nodes, resulting in the routing table shown in Table 20, thus all temporary routes are updated to active routes. Table 20: Node A Destination Nexthop B B D B Routing tables for AODV after a route discovery process. Node B Destination A C D Nexthop A C C Node C Destination B D A Nexthop B D B Node D Destination C Nexthop C After the route discovery process, only B and compare and contrast vs. calling essay C have routes to all other nodes in the scenario. Node A does not know that there is a route to node C, nor does node D know of the route to A and B. Thus AODV has to go through the route discovery process several times to discover all the routes. Value India? This leads to dbq ap world history, more control traffic and higher delays.
On the other hand, it saves memory by not having to keep information about routes that might not be used. 60 DSR The ability to find routes differs slightly between the DSR and value essay india AODV protocol. DSR can make use of the source route carried in each packet header to discover routes to nodes by which the packet has traveled through. If new routes are found, DSR can take advantage of this without having to go through a new route discovery phase, thus reducing the language number of value education essay, control packets and decreasing the delay. Thesis? The memory usage of education india, a node is instead increased by having to store more routes.
We consider the same scenario as for the AODV protocol (Figure 26). Node A needs a route to node D. No data has been sent earlier, thus DSR has no knowledge of any routes. Thesis? Since no routes are known, the RREQ propagates until it reaches node D. During the value india propagation of the RREQ, every node in its path learn a route back to all the nodes by which the RREQ has passed through. The RREP is practice dbq ap world history, unicasted back to A, using the essay india routes learned during the propagation of the RREQ. As the RREP propagates, each node also learns the routes to all nodes for which the RREP has passed through, resulting in the routing tables shown in Table 21. Essay? After the route discovery phase, each node has a route to every other node in this example. Table 21: Node A Destinatio n B C D Path B B-C B-C-D Routing caches for DSR, after a route discovery process. Education India? Node B Destinatio n A C D Path A C C-D Node C Destinatio n A B D Path B-A B D Node D Destinatio n A B C Path C-B-A C-B C 5.7.2 Temporary backward routes When a RREQ propagates in search for a route in texting vs. calling essay, AODV, a temporary backward route is set up towards the requesting node.
A RREP might use this backward route. This route is normally set to education india, expire after 3 seconds if it is not used. It is not clear from the draft if this route may be used by application data as well. Using this route for data affects the behavior of the protocol in compare texting, some way and it is not described how the protocol should handle this. One of the value education essay problems with this temporary route is with the way it is ap lang prompt, set up. Education Essay? When the RREQ propagates, we do not know who will be using the backward route, so no active neighbors can be put into the active neighbor list. If during this time, a link failure or an practice dbq ap world history, expired route entry somewhere breaks the route, the rest of the nodes in the route are not informed of this and therefore have redundant routes in their tables.
When the route is education essay india, used again, the application data will come to memoir thesis, a node in the route that does not have a valid entry for the destination and education india will therefore be dropped while a triggered RREP tries to inform the nodes in world history essay, the route that it is value education essay india, broken. This problem will become more apparent in a network with a higher load. English Introduction? Another problem is the short lifetime if temporary routes are installed into the routing table. Value Essay India? Lets say node A sets up a temporary route to and effect violence, D. Node A can then respond with the temporary route to another request searching for education india a route to D. Since the temporary route has a short lifetime, it might expire before the actual data has a chance to use it. Practice World History Essay? This results in unnecessary control overhead and packet drops. To deal with this, the routing agent could chose to only allow RREP to use the temporary route. Value Education Essay India? Also a check of the expire time before responding with a RREP could be used to assure that the class route wont timeout shortly after the node has responded with the essay information.
A question about cause and effect of domestic violence this was directed to the author of the protocol with the response that this check should not be done, instead the protocol should rely on value education essay india the sequence numbers to provide the freshness of a route. We implemented a version of the AODV protocol that used the temporary route for all packets since it showed a slightly better performance result then if not allowing data packets to use the temporary route. The implementation done in world essay, Gothenburg used the temporary route only for route replies. Value Education Essay? So we have a small difference in our implementations. Memoir Class? 61 5.7.3 Buffers The use of send buffers in the routing protocol also affects the performance of the routing protocol; especially the value essay size of the english language buffers and the time a packet is education, allowed to stay there before it is dropped. The send buffer buffers data packets while the routing protocol requests a route to the destination. In our simulations, AODV used a buffer capable of holding 64 packets and allowing them to stay in the buffer for maximum 8 seconds. Allowing the packets to texting essay, stay in the buffer for longer period of value essay india, times will of compare and contrast texting essay, course increase the value essay amount of successfully routed packets, but also increase the average delay. Also the choice of queuing discipline will affect the practice dbq ap measured performance.
If the buffer is full, there must be some smart algorithm to value, decide which packets should be dropped. The routing protocol could decide not to buffer any packets at practice dbq ap world, all and depend on higher layer protocols such as TCP to retransmit lost packets. This would however affect the measured performance in the simulations and give unfair results for the protocol. 5.8 Discussion If we compare the work that we have done against value the work that was done by the CMU Monarch project , many similarities can be seen. Their conclusion was that both DSR and class AODV performs well at all mobility rates and movement speeds.
We have come to the same conclusion, but we feel however that their definition of mobility (pause time) does not represent the dynamic topology to education, the same extent as our mobility factor that is based on the actual relative movement pattern. The only node speeds that they have tested are 1 m/s and and contrast vs. calling 20 m/s, which are not showing the complete range. Our mobility factor has a speed range from 0 m/s up to 20 m/s and education essay india shows how the protocols behave in the complete range. They have also only shown the result for one DSR version and one AODV version. Memoir Class Thesis? The DSR version that they show the results for essay india is using eavesdropping, which we regard as being unrealistic, because of the security issuses discussed earlier. The AODV version that they have used is dbq ap, not using hello messages, which changes the essay behavior of AODV. We have tested different versions and shown that DSR with eavesdropping has a slightly better performance than DSR without eavesdropping. We have also shown that AODV with MAC-layer support and hello messages has better performance than AODV with only MAC-layer support. Our results also show that it is necessary to use some support from the MAC-layer to achieve a performance that is good even at high mobility factors. The CMU Monarch project, have used the number of sources as a definition of the load that is offered the essay network. Their simulations with the value education essay india different number of sources are almost identical to each other.
The only practice dbq ap world history essay, protocols that showed a significantly difference was TORA, that only delivered 40 % of the packets with the value education essay india lowest pause time and highest number of sources. Our definition of load was based on violence the rate that the sources are sending packets with. Even DSR that had the best results in the CMU paper fails to deliver a large fraction of the education packets when the history essay rate is increased. The increase of the essay rate also very clearly shows how much the essay overhead for DSR increases compared to for instance AODV. 5.9 Classification Why is there any need for classification of routing protocols? If one routing protocol is superior than the other routing protocols for instance in very high mobile environments, why not always use that routing protocol? If it handles high mobile environments, it should also be good at low mobile environments. Education India? In real life, many parameters affect the behavior of the routing protocol.
It is also important to language, recognize the need that is required in india, a particular scenario. Memoir Class? In one scenario, there is maybe more need for high throughput than there is for low delay. In another scenario there is maybe more need for essay india low delay etc. This is becoming more and more important now, in particular when active networks  is becoming an interesting issue in networking. English Essay Introduction? Active networking means that you add user controllable capabilities to the network. The network is no longer viewed a passive mover of bits, but rather as a more general computation engine. This makes it possible for instance to adjust the routing protocol depending on the scenario. You could basically send the routing protocol and let it install itself into value india, the nodes. 62 5.9.1 Mobile networks As the simulation results show, the mobility of the network greatly affects the introduction performance of the value essay india protocols. It is english introduction, crucial that the protocol ability to detect broken routes is fast enough and that they also react to these changes.
DSDV Since DSDV is dependent of its periodic updates, its ability to deal with a dynamic topology is very poor. It has a poor ability to education essay india, fast detect broken links and for research paper takes time to converge. This protocol should really be avoided for use in india, ad-hoc networks where it is crucial to deal with frequent changing topology. Outline For Research Paper? This protocol could however be an option for networks that are static during long periods of times. AODV The original AODV protocol using only HELLO messages as link breakage detection shows poor results as mobility increases. This protocol needs better link breakage detection. Using lower layers such as MAC to detect transmission errors can achieve this. Value Essay? If this is used, the protocol actually shows a very good performance. This protocol is a definite choice for highly mobile networks. DSR This protocol is highly optimized and also shows good results in illegal immigration outline for research paper, the simulations.
The protocol could definitely be used in education, highly mobile networks as well as static networks. And Effect Of Domestic Violence? 5.9.2 Size of networks When talking about the essay size of memoir thesis, a network, it is not only the number of nodes in the network that is of interest. The area that the essay india nodes are spread out over english essay introduction is also interesting. Value Education Essay India? This basically decides the connectivity of the network. A large area with many nodes may mean longer routes then for a smaller area with the outline paper same number of nodes.
At the value education essay india same time, many nodes close to each other means a higher collision probability. DSDV This protocol does not scale well. Its use of periodic broadcasts limits the protocol to small networks. If the protocol would be used in large networks, the converge time to a steady state would increase when routes go up and practice down. The reason is that updates must propagate from one end of the network to india, the other. AODV This protocol scales well, and could be used in both small and medium sized networks. The combination of on-demand and language essay distance vector makes this protocol suitable for education india large networks as well. The information that each node must store for each wanted destination is rather small compared to for instance DSR that has to violence essay, store whole source routes. In large networks however, the value propagation of requests to all nodes is a waste of resources. A better solution is probably to divide the network into clusters or zones, like for instance ZRP and CBRP have done. DSR This protocol has some limitations when it comes to the size of the network.
A larger network often means longer routes and longer routes means that the source overhead in each packet grows. The current implementation limits each packet to carry a source route of maximal 16 hops. This can of course be adjusted, but one should keep in mind the large overhead this causes. Dbq Ap World Essay? One could imagine a network with 20 nodes connected in a straight line. Then this implementation would not manage to route to all nodes. We therefore recommend this protocol for small and medium sized networks.
63 5.9.3 Network scenarios Conference For low mobility scenarios, like the conference scenario that we did simulations on, DSR is the best protocol to use if the hopcount is small (fewer than 5 hops). The reasons are high delivery rate, low delay and essay low message overhead in terms of packets and byte overhead. If the number of hops increases and english introduction get as many as 10 hops, each packet must carry a very large byte overhead, which can be very costly, when the load increases. Another good candidate for this scenario when the number of value education india, hopcount increases is one of the AODV versions that use MAC-layer support. Ap Lang? AODV has also a very high delivery ratio, but the number of control packets is somewhat larger.
Event coverage In average mobile scenarios, like the event coverage scenario, where nodes tends to cluster and almost all communication is within the clusters, DSR is by all means the best protocol. It has a very large delivery ratio and the overhead is very small, even counted in bytes, because of the few hops required to reach the destination. Education Essay? The AODV versions show a very good result also, but the cause of domestic violence essay overhead is larger. So for these type sort of education, networks DSR it the practice dbq ap best protocol. Disaster In networks that become partitioned, DSR with eavesdropping show the best results in this scenario. It has a high delivery ratio, high throughput, a delay around 1.2 seconds and low packet overhead.
It also uses only value education, 5 hops in average to reach a destination. This protocol is therefore recommended in this type of scenario. Eavesdropping might however be undesirable because of security issues. One other candidate for this scenario is AODV with MAC support. It has almost as high delivery ratio as DSR and also a lower delay. The packet overhead is twice as high but the byte overhead is smaller. 5.10 Improvements The simulations have shown that DSR with and without eavesdropping and the AODV versions that use linklayer support has the overall best result in almost all simulations. Cause And Effect Of Domestic Essay? DSR has as mentioned earlier the advantage that it learns more information for value education each request it sends out. If a request goes from S to D and the reply from D to S, S will learn the route to all intermediate routes between S and D. This means that it is not necessary to send out as many requests as for example AODV.
The source routing approach is language, therefore very good in value essay india, the route discovery and route maintenance cases. However, source routing is not desirable to use for data packets. First of all, it adds a lot of overhead. Secondly it is not as traditional as for instance distance vector or link-state that are widely used in wired networks. And Contrast Texting Vs. Calling? Our proposal is therefore to implement a protocol that is a combination of source routing and education essay india distance vector. Source routing should be used in route discovery and illegal outline route maintenance phases. These phases would also include that the routing tables where set up accordingly during the propagation of the requests and replies. When the data packets are forwarded a distance vector algorithm should be used. Education India? The packets are simply forwarded to the nexthop according to the routing table. This in immigration for research paper, combination with that the protocol stores several routes for each destination would probably mean a protocol with a performance that is even better than the protocols that have been simulated in this master thesis.
64 6 Implementation study The implementation study that was conducted at Ericsson Mobile Data Design in Gothenburg  has implemented the education AODV protocol. The goal was to and contrast vs. calling, deliver a working routing protocol as specified in the original AODV draft . Value India? 6.1 Design Main Event Queue Route Table Send Hello Send Request Check Neighb Check sender Remove route Neighbors / Senders Lookup Add Delete Update Need route? Add Delete Update time Is member? Host unreachable Lookup failed Message Request buffer Send request Send reply Send hello Receive msg Add Delete Is member? Rreq Rrep Hello Route add Route del User space /dev/route Iotcl() Icmp.c UDP FIB Kernel Table Kernel route.c Other daemons Figure 27: Overview of dbq ap history, AODV daemon. The implementation that has been done should only be considered as a prototype to value, confirm the vs. calling essay usefulness of AODV. It is implemented as a daemon in user space. The advantage with this is that debugging and testing is much easier to do.
A final implementation should be made in kernel space with more optimized design. Thus abandon the education modular design and optimize the code to go really fast. Figure 27 shows the design of the user space daemon and how it interacts with the kernel code. The different modules will be explained in the following chapters. 6.1.1 Main Main ties together all other modules of the dbq ap history essay user space daemon. Education Essay India? It is also in main that the language AODV specific code lies. Value Education India? 65 6.1.2 Event queue Queue for events that are supposed to be performed at certain times. These events include: N N N N Periodic hello messages Send / retransmit route requests Timeouts of route entries Hello timeout 6.1.3 Route table This module is an compare and contrast essay, interface against the submodules Daemon Table and value education essay india Kernel Table. Cause And Effect Of Domestic Essay? It takes care of these two, so when you want to lookup or change a route from Main, you only have to do one call to this module instead of two to the both submodules.
The entries in Daemon Table module have all the fields that is required for AODV, sequence number, list of value, active neighbors and so on. The operations supported are Lookup, Add and Delete. Compare Texting? The Kernel Table is not a table in the sense Daemon Table is, instead this submodule just communicates with the education essay kernel, sending messages about adding and deleting entries and receives netlink need-route messages. 6.1.4 Neighbors / senders Keeps track of the neighbors of immigration outline for research, a node. A neighbor is education essay, a host that sends/receives hello messages that is directly received/sent by another node. Analysis Prompt? This demands that the value india links are bi-directional. At first it was thought that the WaveLAN cards would take care of this, but it was not the case. The signal strength and the range was different between the hosts. To be able to guarantee bi-directional link, the concept Sender was added. A host is classified as a sender if it can be heard by at least one other node. When sending hello messages a node sends the list of class, current Senders and essay if the receiver of the Hello messages is in this list, it is a Neighbor and introduction can start act as one 6.1.5 Request buffer This buffer prevents the network of being flooded by multiple request for the same address.
This buffer stores already processed requests. 6.1.6 Message Handles the different types of messages that the daemon can send and receive. These messages are: N N N Hello Route Request Route Reply. 6.2 Setup The computers used for education india this implementation study was: N N 2 stationary computers with Lucent WaveLAN ISA cards. Practice? 3 laptops with Lucent WaveLAN PCMCIA cards.
The implementation started first with the 2 stationary computers running FreeBSD7. The choice of FreeBSD was primarily made because FreeBSD offers the best documentation of its kernel source. It was later discovered when the laptops arrived that FreeBSD was incompatible with the Lucent WaveLAN PCMIA cards in the laptops. Linux8 however has support for both variants of the LucentWaveLAN cards and Linux was therefore chosen as development operating system. It is not very hard to port the code to FreeBSD in the future if so desired. 7 8 FreeBSD 2.2.6 Linux Red Hat 5.1 66 6.3 Testing The purpose of testing the implementation is to verify that the implementation works correctly and to see if the performance is suitable for real life applications. 6.3.1 Correctness To verify that the value implementation of AODV behaved correctly, computers were placed in cause of domestic violence, different scenarios to essay india, test the different parts of the language protocol. The following tests where made: N N N N N N N Bi-directional links and value education essay neighbors: Tests that two nodes can send hello messages to english language essay introduction, each other and registry the counterpart as a neighbor. Unidirectional links and neighbors: It tests the same as above, but with the difference that we only have an uni-directional link, so only one of the nodes can hear the other and registry him as a neighbor. Value Education Essay India? Neighbor link down: Tests that neighbors moving away from each other causes the link between them to go down. Zero hop route requests: Tests that a request to a neighbor that also is the requested destination generates a reply that is correctly received.
This is memoir class thesis, not the normal operation of the protocol, but could happen if two nodes are in range but have not accepted each other as neighbors. Education Essay India? Single hop route request: Tests the situation where node S searches the route to D and we have one node B in between. S broadcasts a request that is caught by B, which knows the essay route to D and education essay india sends a reply back to S. Multihop route request: Almost the same situation as the single hop route request. English Essay? The difference is value, that we have two nodes between the requesting source and the destination. The route request must therefore be forwarded one hop before a reply can be generated.
Triggered route reply: Tests that the triggered route reply is generated whenever a route goes down. 6.3.2 Performance No actual performance tests were done. The results for vs. calling so few nodes would be misleading. Instead tests with real applications like Netscape and Telnet were done. Value India? The problems that occurred with these tests were related to the on-demand nature of AODV. Essay? Telnet for essay india instance returns host-unreachable when trying to telnet to a computer on illegal immigration outline paper the first attempt. The second attempt however is successful. The reason is that when Telnet makes its first attempt, no route to the destination exists.
This will result in an error message from the kernel to Telnet, at the same time as a new request is sent to the neighbors. This request will eventually find a route to value, the destination and ap lang analysis essay it is education, installed in vs. calling, the routing table. When Telnet makes a second attempt connect to education essay, the same host, a route will already exist in the routing table and ap lang telnet will successfully reach the value destination host. The solution to this problem is memoir, simply to take care of the error messages that the kernel sends to the application. The error message should be buffered and if a route is not found in a certain amount of time, the error message should be sent to the application, but if a route is actually found the error message can be discarded. 6.4 Problems / Limitations Problems that occurred during the implementation include: N N N FreeBSD incompatibilities: As mentioned before, lack of essay, functional drivers to FreeBSD forced the implementation study to be done under Linux. And Effect Of Domestic Violence Essay? Address: The current prototype requires that each node participating in value education india, the network have a predefined unique IP-address. There is a great need for a dynamic assigned IP-address architecture, which assigns nodes IP-addresses as they enter the network. IPv6 holds such functionality. Texting? This prototype is value essay india, however done for IPv4 so no consideration has been done to compare and contrast texting vs. calling, implement such functionality. Three-way handshake: To guarantee bi-directional links, a three way handshake was necessary for the hello messages before two nodes can be certain of the value other nodes existence.
The handshake uses piggybacking. It concatenates a list of all nodes it receives hello messages from to the hello messages it sends. When a node receives a hello message and practice dbq ap world finds its own address in value education essay india, the concatenated list it will add the sending node to its own list of neighbors which it has bi-directional links to. Three hello 67 N messages instead of one wastes bandwidth, but could also in a worst case scenario mean that it could take as long as two full hello intervals before two nodes in paper, range of each other accepts the bi-directional links. Essay? Temporary routes: When a request is broadcasted from a node, it will propagate through the network and at the same time install a temporary route back to and contrast texting vs. calling essay, the source.
The problem with this temporary route is first of essay, all that the request is unaware of if the memoir route ever will be used and secondly who will use it. This means that it does not know the active neighbors that are using this entry and can therefore not inform these neighbors if a link should go down on this route. The solution that was implemented differs somewhat of what was done in the simulation study. The solution is to store the temporary routes separately and value education india only install them in the routing table when the route reply is and effect of domestic violence, propagating back through the network. Education? 6.5 Improvements Possible features that could be added to this prototype: N N N N Link layer hellos: The addition of compare texting, link layer feedback from 802.11 would significantly increase the performance as the simulation study has shown. Redundant routes: Store all routes to a destination, not only the essay one we are currently using. If a route goes down due to a link failure, the next stored route would be tried before a new request is to practice world essay, be sent. Education Essay India? This saves a lot of overhead a and makes the delay somewhat smaller. Dynamic IP-addresses: As mention under limitations, dynamic address assignment is language introduction, a requirement for these kind of networks.
Multicast: Multicast groups within a ad-hoc network could be added. The latest AODV draft has support for value education india this. 6.6 Implementation conclusions The implementation of the AODV protocol has shown that it is cause and effect of domestic violence, possible to get these protocols to work in real-life. It must however be noted that real-life in this case only consisted of five computers. The AODV prototype has also given some insight into the problems that arise when trying to value essay, run real applications on and effect of domestic violence an ad-hoc network. Applications like Netscape and Telnet get host unreachable in the first attempt. The second attempt finds the route successfully. This has to do with the on-demand feature of the AODV protocol.
68 7 Conclusions 7.1 Results The simulations have shown that there certainly is a need for a special ad-hoc routing protocol when the mobility increases. It is however necessary to have some sort of feedback from the link-layer protocol like IEEE MAC 802.11 when links go up and down or for neighbor discovery. To only be dependent on periodic messages at value education essay india, the IP-level will result in a very high degree of packet losses even when mobility increases a little. The simulations have also shown that more conventional types of protocols like DSDV have a drastic decrease in performance when mobility increases and are therefore not suitable for mobile ad-hoc networks. AODV and DSR have overall exhibited a good performance also when mobility is high.
DSR is however based on source routing, which means that the illegal paper byte overhead in each packet can affect the total byte overhead in the network quite drastically when the essay offered load to the network and compare texting vs. calling essay the size of the network increases. In these situations, a hop-by-hop based routing protocol like AODV is more desirable. Essay? One advantage with the source routing approach is however that in its route discovery operation it learns more routes. Source routing is however not desirable in analysis essay, ordinary forwarding of data packets because of the value education large byte overhead. A combination of AODV and analysis prompt DSR could therefore be a solution with even better performance than AODV and DSR. Education India? Another key aspect when evaluating these protocols is to test them in violence essay, realistic scenarios. We have tested them in three types of scenarios. Value India? DSR had the best performance, but the large byte overhead caused by the source route in each packet makes AODV a good alternate candidate.
It has almost as good performance. The implementation study conducted at ERV in Gothenburg has shown that it is possible to get a real ad-hoc network up and running. The main problems that did occur were related to the testing of the protocol with real applications. Essay? When a route was needed by the application and the route did not exist in the routing table, the value education essay india kernel informed the applications of compare and contrast, a connection error before giving the value routing protocol enough time to find a route. Practice World History? 7.2 Further studies Ad-hoc networking is a rather hot concept in computer communications.
This means that there is much research going on and many issues that remains to be solved. Due to value, limited time, we have only focused on the routing protocols. However there are many issues that could be subject to further studies. First of all, the simulator environment could be improved. Memoir Thesis? These are just some of the improvements that could be made: N N More routing protocols, for instance TORA, ZRP and CBRP. Measurement of education, computing complexity.
Secondly, there are many issues related to ad-hoc networks that could be subject to further studies: N N N Simulations which take unidirectional links into consideration. Some sort of analysis of whether many small control messages are more costly to class thesis, send in value, terms of resources than fewer large control messages. Security: A very important issue that has to be considered is the security in an ad-hoc network. Routing protocols are prime targets for impersonation attacks. Because ad-hoc networks are formed without centralized control, security must be handled in a distributed fashion.
This will probably mean that IP- 69 N N N N N N Sec  authentication headers will be deployed, as well as the necessary key management to distribute keys to dbq ap, the members of the ad-hoc network. Quality of Service (QoS): What needs are there for Quality of Service in an ad-hoc network? This is related to what the networks actually will be used for. Hand-over of real-time traffic between nodes. How should real-time traffic smoothly be handed over to another node when a route goes down? Should flooding be used before a route is value education essay india, found? Multicast: We have only looked at unicast routing. Multicast routing is also an interesting issue that has to be considered.
Connecting ad-hoc networks to of domestic, the Internet through access points: How do you connect an value essay, ad-hoc network to the Internet? It is practice dbq ap world history essay, not possible to just add the access point as default in the routing tables. This would mean that nodes without a route to a certain destination would be routed to the Internet. Mobile IP: Integration of mobile IP into ad-hoc networks. Addressing of value essay india, hosts: How should the hosts in english essay introduction, an ad-hoc network be addressed? What happens if one adhoc network is education essay, partitioned in to and contrast essay, two separate networks or two ad-hoc networks are merged into one new larger ad-hoc network? IP Index Router IP Router (IP) Index Index Figure 28: Router (RID) IP IP Different router identification approaches. From left to right: 3a, 3b, 3c. Education India? There are basically three types of thesis, identifiers to consider (Figure 28): 1) Interface identifiers: Interfaces are present on both routers and hosts.
In the Internet addressing architecture, interfaces are identified by IP addresses. 2) Host identifiers: Can either be a permanent identifier or a temporary identifier. 3) Router identifiers: Is unspecified and generally depends on the routing policy. There are three approaches to MANET router identification and addressing currently being considered: a) Single IP address (AODV): Identifies a MANET node (both the router and the host) with a single IP address. This approach leaves several issues open: N How to support sets or subnets of hosts attached to value, a MANET router?
N How to support the use of multiple wireless interfaces? b) Single IP address with interface indexes (DSR): Identifies a MANET router with a single IP address and each interface with a single-byte interface index. This makes it possible to enable simultaneous support for multiple wireless technologies, with the IP address acting as router identifier. World History? The problem with this scheme is that it is education, not IP in the classical sense where interfaces are identified by IP addresses. The use of a non-standard addressing architecture will likely complicate interoperability. c) Router identifier and IP interface addresses (IMEP): Identifies a MANET router with a router Identifier (RID) and identifies each interface with an IP address. This approach can support sets or subsets of compare vs. calling, attached hosts and simultaneous use of multiple wireless technologies.
Approach a) and b) seem tailored to support a mobile host that acts like a router. Approach c) is intended to support a mobile router platform to which one or more host-like devices may be permanently or temporally affiliated. These approaches say nothing about how IP addresses are assigned to interfaces (on hosts or routers), or what the RID is and how it is assigned. This is a separate problem, although one which is related to routing. 70 8 References  Dimitri Bertsekas and Robert Gallager, “Data Networks - 2nd ed”. Prentice Hall, New Jersey, ISBN 013-200916-1.  Bommaiah, McAuley and Talpade. AMRoute, “Adhoc Multicast Routing Protocol”, Internet draft, drafttalpade-manet-amroute-00.txt, August 1998. Work in progress.  Josh Broch, David A. Maltz, David B. Johnson, Yih-Chun Hu and essay Jorjeta Jetcheva, “A performance Comparison of Multi-hop Wireless Ad Hoc Network Routing Protocols”. Mobicom'98, Dallas Texas, 25–30 October, 1998.  Josh Broch, David B. Johnsson, David A. Prompt? Maltz, “The Dynamic Source Routing Protocol for education essay india Mobile Ad Hoc Networks”. History? Internet Draft, draft-ietf-manet-dsr-00.txt, March 1998. Work in value, progress.  Scott Corson and Joseph Macker, “ Mobile Ad Hoc Networking (MANET): Routing Protocol Performance Issues and outline for research paper Evaluation Considerations”.
Internet-Draft, draft-ietf-manet-issues-01.txt, March 1998. Essay India? Work in progress.  M.Scott Corson, S. Ap Lang Analysis Essay Prompt? Papademetriou, Philip Papadopolous, Vincent D. Park and Amir Qayyum, “An Internet MANET Encapsulation Protocol (IMEP) Specification”. Internet draft, draft-ietf-manet-imepspec01.txt, August 1998. Education Essay? Work in progress.  Kevin Fall and Kannan Varadhan, “ns notes and documentation”. The VINT project, UC Berkeley, LBL, USC/ISI, and Xerox PARC, May 1998. English Essay? Work in progress. Education?  Zygmunt J. Haas and Marc R. Pearlman, “The Zone Routing Protocol (ZRP) for Ad Hoc Networks”, Internet draft, draft-ietf-manet-zone-zrp-01.txt, August 1998.
Work in progress.  IEEE Computer Society LAN MAN Standards Committee, “Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications”, IEEE Std 802.11-1997. Analysis Essay Prompt? The Institute of Electrical and Electronics Engineers, New York.  Philippe Jacquet, Paul Muhlethaler and Amir Qayyum, “Optimized Link State Routing Protocol”. Internet draft, draft-ietf-manet-olsr-00.txt, November 1998. Essay? Work in english introduction, progress.  Mingliang Jiang, Jinyang Li and value education Yong Chiang Tay, “Cluster Based Routing Protocol (CBRP) Functional specification”. Illegal Immigration Outline For Research? Internet draft, draft-ietf-manet-cbrp-spec-00.txt, August 1998. Work in progress. Education Essay?  David B. Johnson and David A.Maltz, “Dynamic source routing in cause essay, ad hoc wireless networks”. In Mobile Computing, edited by Tomasz Imielinski and Hank Korth, chapter 5, pages 153-181. Kluwer Academic Publishers.  David B. Johnson and David A. Maltz, “Protocols for adaptive wireless and education essay mobile computing”. In IEEE Personal Communications, 3(1), February 1996.  Stephen Kent and Randall Atkinson, “Security Architecture for the Internet Protocol”, Internet draft, draft-ietf-ipsec-arch-sec-07.txt, July 1998.
Work in progress. Memoir Thesis?  Mobile Ad-hoc Networks (MANET). URL: http://www.ietf.org/html.charters/manet-charter.html. (1998-11-29). Work in progress. Value Education Essay India? 71  Vincent D. Park and M. Texting Essay? Scott Corson, “Temporally-Ordered Routing Algorithm (TORA) Version 1: Functional specification”. Value Education Essay? Internet draft, draft-ietf-manet-tora-spec-01.txt, August 1998. Compare Vs. Calling Essay? Work in progress.  Vincent D. Park and M. Scott Corson, “A performance comparison of the Temporally-Ordered Routing Algorithm and Ideal Link-state routing”. In Proceedings of IEEE Symposium on Computers and Communication ’98, June 1998.  Charles E. Value Education Essay? Perkins, “Mobility support, Mobile IP and Wireless Channel Support for analysis essay ns-2”, presentation slides. Value Education? URL: http://www.svrloc.org/ charliep/mobins2/, (1998-11-29). Work in progress.  Charles E. Perkins, “Ad Hoc On Demand Distance Vector (AODV) Routing”. Internet draft, draft-ietfmanet-aodv-01.txt, August 1998.
Work in progress.  Charles E. Perkins, “Ad Hoc On Demand Distance Vector (AODV) Routing”. Internet draft, draft-ietfmanet-aodv-02.txt, November 1998. Work in progress.  Charles E. Perkins, “Mobile Ad Hoc Networking Terminology”. Practice Dbq Ap History Essay? Internet draft, draft-ietf-manet-term00.txt, October 1997. Work in progress. Education Essay?  Charles E. Perkins and illegal paper Pravin Bhagwat, “Highly dynamic Destination-Sequenced Distance-Vector routing (DSDV) for mobile computers”. In Proceedings of the SIGCOM '94 Conference on Communications Architecture, protocols and Applications, pages234-244, August 1994. A revised version of the paper is available from education essay http://www.cs.umd.edu/projects/mcml/papers/Sigcomm94.ps. (1998-11-29)  Larry L. Peterson and Bruce S. Davie, “Computer Networks - A Systems Approach”. Language Essay Introduction? San Francisco, Morgan Kaufmann Publishers Inc. ISBN 1-55860-368-9.  Plummer, D., An Ethernet Address Resolution Protocol - or - Converting Network Protocol Addresses to value essay, 48.bit Ethernet Address for Transmission on Ethernet Hardware, RFC-826, MIT, November 1982.  Theodore S. Rappaport, “Wireless Communications: Principles and Practice”. New Jersey, Prentice Hall. ISBN 0-13-375536-3. Practice?  Raghupathy Sivakumar, Prasun Sinha and Vaduvur Bharghavan, “Core Extraction Distributed Ad hoc Routing (CEDAR) Specification”, Internet draft, draft-ietf-manet-cedar-spec-00.txt, October 1998.
Work in progress.  Martha Steenstrup, “Routing in communication networks”. New Jersey, Prentice Hall. ISBN 0-13010752-2.  Jerry Svedlund and value essay india Johan Kopman, “Routing protocols in wireless ad-hoc networks - An implementation study”. Violence? Uppsala: Uppsala University. Master thesis.  D. L. Value Education India? Tennenhouse and D. Wetherall, “Towards an cause and effect of domestic violence, active network architecture”. In Multimedia Computing and Networking 96, San Jose, CA, Jan 1996. Essay?  The CMU Monarch Project. “The CMU Monarch Projects Wireless and Mobility Extensions to ns”. URL: http://www.monarch.cs.cmu.edu/. (1998-11-29).
Work in progress. 72 Appendix A -Terminology This appendix contains some terminology  that is related to ad-hoc networks. Immigration For Research Paper? A.1 General terms Bandwidth: Total link capacity of a link to essay india, carry information (typically bits). Channel: The physical medium is divided into memoir class, logical channel, allowing possibly shared uses of the medium. Channels may be made available by subdividing the medium into education essay, distinct time slots, distinct spectral bands, or decorrelated coding sequences. Thesis? Convergence: The process of approaching a state of value india, equilibrium in which all nodes in the network agree on a consistent state about the topology of the practice history network.
Flooding: The process of education essay india, delivering data or control messages to memoir class thesis, every node within the any data network. Host: Any node that is essay, not a router. Interface: A nodes attachment to essay, a link. Value? Link: A communication facility or medium over practice world essay which nodes can communicate at the link layer. Loop free: A path taken by a packet never transits the same intermediate node twice before arrival at the destination. Value India? MAC-layer address: An address (sometimes called the link address) associated with the and contrast link interface of a node on a physical link. Next hop: A neighbor, which has been designated to forward packets along the way to value education, a particular destination. Neighbor: A node that is within transmitter range from another node on the same channel. Node: A device that implements IP.
Node ID: Unique identifier that identifies a particular node. Router: A node that forwards IP packets not explicitly addressed to itself. In case of ad-hoc networks, all nodes are at least unicast routers. English Language Essay? Routing table: The table where the routing protocols keep routing information for various destinations. This information can include nexthop and the number of hops to the destination. Scalability: A protocol is scalable if it is applicable to large as well as small populations. Source route: A route from the source to the destination made available by the source. Throughput: The amount of data from a source to education essay india, a destination processed by the protocol for which throughput is to be measured for instance, IP, TCP, or the MAC protocol. 73 A.2 Ad-hoc related terms Ad-hoc: For this special or temporary purpose or a special case without generic support. AODV: Ad-Hoc On-Demand Distance Vector.
Routing protocol for wireless ad-hoc networks. Asymmetric: A link with transmission characteristics that are different of the transmitter and receiver. English Introduction? For instance, the range of one transmitter may be much higher than the range of another transmitter on the same medium. The transmission between the two hosts will therefore not work equally well in value education essay india, both directions. See also symmetric. English Language Introduction? Beacon: Control message issued by a node informing other nodes in its neighborhood of its continuing presence. Bi-directional: see symmetric. CBRP: Cluster Based Routing Protocol. Routing protocol for wireless ad-hoc networks.
Cluster: A group of essay, nodes typically in range of each other, where one of the immigration nodes is elected as the cluster head. The cluster head ID identifies the cluster. Each node in the network knows its corresponding cluster head(s) and therefore knows which cluster(s) it belongs to. DSDV: Dynamic Sequenced Distance Vector. Routing protocol for value wireless Ad Hoc networks. DSR: Dynamic Source Routing. Routing protocol for wireless Ad Hoc networks. Of Domestic? Proactive: Tries to maintain the routing map for the whole network all the time.
See also reactive. Reactive: Calculates route only upon value education essay, receiving a specific request. English Language? See also proactive RREQ: Routing Request. A message used by AODV for education essay india the purpose of discovering new routes to dbq ap history, a destination node. RREP: Route Reply. Education Essay? A message used by AODV to illegal, reply to route requests. Symmetric: Transmission between two hosts works equally well in both directions.
See also asymmetric. TORA: Temporally Ordered Routing Algorithm. Value Education India? Routing protocol for wireless ad-hoc networks. English Language Essay? Unidirectional: see asymmetric. ZRP: Zone Routing Protocol. Routing protocol for wireless ad-hoc networks. 74 Appendix B - AODV implementation for ns This appendix contains a little more details about the implementation of AODV that we did for india ns. The implementation of AODV is done according to the draft  released in August 1998. B.1 Message formats AODV have four different messages that it uses for route discovery and route maintenance.
All messages are sent using UDP. Illegal Immigration Paper? B.1.1 Route Request – RREQ The format of the route request message is shown in Figure 29. 0 1 2 31 01234567890123456789012345678901 Type Reserved Hop count Broadcast ID Destination IP address Destination Sequence Number Source IP address Source Sequence Number Figure 29: N N N N N N N N Route request format. Type: Type of message. Reserved: Reserved for future use. Currently sent as 0 and ignored on reception. Hop count: Number of hops from the source IP address to essay, the node handling the request. Broadcast ID: A sequence number identifying the particular request uniquely when taken in conjunction with the source nodes IP address.
Destination IP address: IP address of the destination for which a route is required. Thesis? Destination sequence number: The last sequence number received in the past by the source for any route towards the destination. Source IP address: IP address of the value education node that originated the and effect of domestic request. Value Essay India? Source sequence number: Current sequence number for and effect violence essay route information generated by the source of the route request. 75 B.1.2 Route Reply - RREP The format of the route reply message is shown in education india, Figure 30. 0 1 2 31 01234567890123456789012345678901 Type L Reserved Hop count Destination IP address Destination Sequence Number Lifetime Figure 30: N N N N N N N Route reply format. Type: Type of message. L: If the L-bit is set the message is a hello message and contains a list of the nodes neighbors. Reserved: Reserved for future use. Currently sent as 0 and ignored on reception. Hop count: Number of essay, hops from the source IP address to the destination IP address.
Destination IP address: IP address of the destination for value education which a route is supplied. Destination sequence number: The destination sequence number associated to the route. Lifetime: Time for which nodes receiving the Reply consider the route to be valid. B.1.3 Hello Hello messages are a special case of for research paper, Route reply messages. Value Essay India? The difference is that a hello message always supplies the route to illegal for research, itself. This means that the hop count field is set to 0, the value india destination address set to the nodes IP address and the destination sequence number set to the nodes latest sequence number.
B.1.4 Link failure Link failure messages are also special Route reply messages, but in this case the destination reflects the route that has broken. The broken route is assigned an infinite hop count and a sequence number that is increased with one. 76 B.2 Design Figure 31 shows how AODV was designed when implemented for ns. AODV OTcl C++ AODV_Agent Hdr_AODV Request Buffer Figure 31: AODV_RTable AODVConstants AODV design of implementation for simulator. AODV The tcl script that starts the and effect of domestic violence AODV routing agent and creates all mobile nodes that are using AODV as routing protocol. AODV_Agent Implements all AODV specific parts.
Handles RREQ, RREP, Hello and value education essay Triggered RREP. It also has a send buffer that buffers packets while a route is searched for. Illegal Outline Paper? The timers that handles timeouts on route entries and the send buffer are also implemented here. Hdr_AODV Defines the message format for value education india all messages that AODV uses. Request Buffer Implements the request buffer that prevents a node to process the essay same RREQ multiple times. AODV_RTable The routing table that AODV uses. The routing table also implements the active neighbor list for each route entry. AODVConstants All AODV constants are defined here, which makes it easy to modify for instance the hello interval. Education Essay India? 77 B.3 Important routines B.3.1 Sending RREQ RREQ will only texting vs. calling essay, be sent by the source nodes (no intermediate nodes sends RREQs), if there does not exist any route for the destination. 1. 2. 3. 4. 5. 6. Value Education India? 7. 8. 9. 10. 11.
12. B.3.2 if ( no route exists ) else Receiving RREQ When a node receives a RREQ, it must first of all decide if it already has processed the RREQ. The RREQ is for research paper, discarded if it has been processed. Otherwise the source address and the broadcast ID from RREQ will be buffered to prevent it from being processed again. 1. Essay? 2. 3. 4. 5. if ( (source addr, broadcast ID) in request buffer ) else The next step is to create or update the route entry in the routing table. This route can be used by the RREP when a route is found.
1. 2. English Essay? 3. 4. 5. 6. 7. Essay India? 8. Of Domestic? if ( no route to source addr ) elseif ( source seqno in RREQ source seqno in route entry ) elseif ((source seqno in value education essay, RREQ = source seqno in route entry) AND ( hop count in RREQ hop count in language, route entry )) Then, the value essay node must check if it knows the route to the wanted destination. Violence Essay? If the node knows the route it will unicast a RREP to value education essay, the source. Otherwise it will forward the RREQ. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. if ( you are destination of RREQ ) elseif (( have route to destination ) AND (destination seqno in route entry = destination seqno in RREQ)) else 78 B.3.3 Forwarding RREQ When a node receiving a RREQ that it has not processed yet does not have a route, it will forward the RREQ. 1. Cause Violence? 2. Value India? 3. 4. 5. create a RREQ packet: copy all fields from received RREQ into new packet increment hop count field locally broadcast new RREQ packet discard received RREQ B.3.4 Forwarding RREP When a node receives a RREP that is not addressed for illegal immigration outline for research paper the node, it will set up the forward route by updating the routing table and forward the RREP back to the requesting source. This part is however not explicit specified in the AODV draft. 1. Essay? 2. Practice Dbq Ap? 3. 4. 5. 6. 7. 8. 9. 10. 11. 12.
13. Education India? if ( route to requested destination does not exist ) elseif(destination seqno in RREP destination seqno in route entry) elseif ((destination seqno in RREP = destination seqno in route entry ) AND ( hop count in RREP hop count in entry )) if (route to requesting source exists) B.3.5 Receiving RREP When the originating source receives the RREP it will update the dbq ap history essay routing table. 1. 2. 3. 4. 5. 5. 6. Value Education Essay India? 7. 8. 9. 10. 11. if (route to destination does not exist) elseif (destination seqno in RREP destination seqno in route entry) elseif (( destination seqno in RREP = destination seqno in route entry ) AND (hop count in RREP hop count in practice dbq ap history essay, entry )) else 79 B.3.6 Hello handling Each node periodically broadcasts a hello message to all neighbors. When a node receives a hello message it knows that the value sending node is a neighbor and will update the english essay introduction routing table. 1. 2. 3. Essay India? 4. 5. 6. 7. 8. 9. B.3.7 if (route entry for HELLO source exists) else Forwarding packets AODV uses a active neighbor list to keep track of which neighbors that are using a particular route. Violence Essay? These lists are used when sending triggered route replies. The neighbor lists are updated every time a packet is forwarded. Essay India? 1. 2. 3. Essay Introduction? 4. 5. 6. B.3.8 if (route entry to destination exists) Sending Triggered RREP Link breakages are detected by either the link layer which notifies the routing agent or by education essay india, using hello messages. English Essay Introduction? If a node has not received hello messages from education essay india a node for a certain amount of time it will assume that the link is down. Every time a link is detected as down, AODV will send a Triggered RREP to inform the affected sources. 1. 2. 3. 4. B.3.9 for vs. calling (each address in the active neighbor list for a route entry) Receiving Triggered RREP Every time a Triggered RREP is received informing about a broken link, the affected route entry must be deleted and neighbors using this entry must be informed.
1. 2. 3. 4. if (have active neighbors for broken route) delete route entry for broken route 80 Appendix C -Simulator screenshots This appendix shows some screenshots of Network animator and Ad-hockey. Network animator is the visualization tool for ns and india Ad-hockey is the visualization for the mobility extension developed by the CMU Monarch project. C.1 Network animator Figure 32 shows a screenshot of Network animator. The scenario contains 19 nodes in texting, a wired network. Some of the nodes are sending packets, which also can be seen in the figure. With this tool it is very easy to trace packets as they propagate through the value essay network. The circles represent the nodes and the lines between the circles are the physical wired links that connect the nodes with each other. Figure 32: Screenshot – Network animator. 81 C.2 Ad-hockey The screenshots of dbq ap world essay, Ad-hockey that can be seen in Figure 33, Figure 34 and Figure 35 shows the playback trace of the value realistic scenarios that with did simulations on.
The big white rectangle in the middle is the movement area. The different colored circles are the nodes. The colors of the nodes represent what action the nodes are performing at the moment. It could for and contrast vs. calling instance be that the node is sending, forwarding or receiving a packet. The lines between the nodes do not represent wired links. The lines are actually packets that propagate from node to node. The detached rectangles and lines that also can be seen within the value education movement area are obstacles. Figure 33: Screenshot – Ad-hockey – Conference scenario. Practice World Essay? 82 Figure 34: Screenshot – Ad-hockey – Event coverage scenario. Figure 35: Screenshot – Ad-hockey – Disaster area. 83 . TERM Spring #039;00 PROFESSOR Hesham TAGS Computer network, . routing protocol, ad-hoc network.
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PARALLEL_COMPUTING_PLATFORM_ICSPC07 Newcastle ECON 101 - Spring 2000 PARALLEL COMPUTING PLATFORM FOR EVALUATING LDPC CODES PERFORMANCE Esa Alghonaim, Aima. Bruvold_dissertation_2005 Newcastle ECON 101 - Spring 2000 UNIVERSITY OF CALIFORNIA Santa Barbara Cross-Layer Design for Ecient Wireless Medium. How to write a good paper Newcastle ECON 101 - Spring 2000 How to write a paper Toby Walsh National ICT Australia and UNSW, Sydney http:/www.cse. How to write a good paper. Average end to education, end delay This is the average time delay for data packets from Ms Ramaiah Institute Of Technology CS 303 - Fall 2016 International Journal of Scientific and Research Publications, Volume 2, Issue 9, Sep. adhoc_routing_protocols UCLA CS 218 - Spring 2015 RoutingProtocolsforAdHocNetworks AdhocOnDemandDistanceVector Routing DSR:TheDynamic. 2 Dynamic Source Routing Disadvantages Packet header size grows with route National Institute of Technology, Calicut COMP it-441 - Spring 2011 European Journal of immigration paper, Scientific Research ISSN 1450-216X Vol.39 No.4 (2010), pp.606-612. IJETAE_0312_59 Ms Ramaiah Institute Of Technology CS 303 - Fall 2016 International Journal of Emerging Technology and essay india Advanced Engineering Website: www.ij. 14 Routing in MANETs Routing protocols should support the highly dynamic nature Al-Sirat Degree College OPERATION 4572 - Spring 2017 ng Thanh Bnh Chapter 7 Adhoc Networks Contents Introduction Characteristics of MANETs.
07 Adhoc Networks. Nodes J and K both broadcast RREQ to node D Since nodes J and K are hidden from class Vietnamese-German University, Binh Duong Province EEIT 28 - Winter 2016 Lecture (11-14) -On-Demand-Driven Reactive Routing protocols Chandra Prakash Assistan. Copyright © 2017. Course Hero, Inc. Privacy Terms.
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Seven Common Resume Mistakes Pastors Make. With some 400,000 congregations in the United States, the way each church secures a pastor is widely varied. Some churches receive pastors through a denominational appointment system. Other congregations seek a pastor totally independent of any hierarchy. They seek, interview, and education essay vote in a totally autonomous fashion. Still other churches secure a pastor in some combination of the analysis prompt two approaches. In many of these situations, the church requests resumes of prospective pastors as an initial consideration process. I have worked with countless churches helping them to value, secure and understand the resumes they have received. Indeed I have looked at thousands of resumes. Immigration. Many of them are excellent.
Others are, well, not. Allow me to india, share with you seven of the more common resume mistakes I see. Any one of these mistakes will likely cause that particular person to be eliminated from consideration. 1. Sloppy resumes. These sloppy resumes have careless grammatical and stylistic errors. Capitalization is random and spacing is unpredictable. Memoir Class Thesis. There is no discernible pattern to how the different items on the resume are placed. Just yesterday I heard from a church that eliminated a prospective pastor from value essay india, consideration because his resume was so sloppy. “If he approaches ministry with this much disregard,” the layman told me, “he certainly will not do well at this church.” 2. Unverified statistics. It is common and acceptable to put such statistics as worship attendance and the church budget of the pastor’s current church on the resume.
Make certain that the numbers are accurate. Otherwise it will appear that the pastor is careless at best and duplicitous at worst. 3. Bad photos. Not all pastors choose to put a photo on a resume. If the and effect of domestic violence pastor does decide to use a photo, it should be one of high quality of him or of him with his family. Education India. I still am surprised to see how many photos are candid shots that belong on Facebook, or they are of such poor quality that facial features are hardly discernible. 4. Poor presentation of outline for research family. The mistakes here are usually one of two extremes.
Some pastors leave off their family entirely. The prospective church is left to wonder if the pastor’s family is a priority for him. On the other extreme, I have seen resumes that include so much detail about the pastor’s spouse that it becomes muddled who is really seeking a position. 5. Value Essay India. No sense of prioritization. Typically, church leaders receiving resumes presume that how a pastor orders different areas on his resume reflects his priorities. Class. If education is presented first, that is his priority. If family is noted first, that then becomes the perceived priority.
I have seen too many resumes that simply don’t make sense in the manner items are presented. 6. Failure to note ministry accomplishments. Those who receive prospective pastor resumes want to know more than the name and address of churches or other places of ministry and employment. Education Essay India. They want to know what was accomplished during that tenure. Illegal Outline For Research. Of course, pastors must be careful in how they present such information lest they appear to be bragging or failing to give God the glory. 7. Failure to value education essay india, explain gaps in date. If a pastor has a two or three year gap on his resume, he needs to explain it.
It is memoir thesis, better to essay india, provide a succinct explanation of what transpired leading toward those years than to leave the recipients wondering. What have you noticed about pastors’ resumes? What would you add to my list? Pastor to Pastor is the Saturday blog series at english essay introduction ThomRainer.com. Pastors and staff, if we can help in essay india any way, contact Steve Drake, our director of memoir class thesis pastoral relations, at [email protected] . We also welcome contacts from laypersons in value education churches asking questions about pastors, churches, or the world essay pastor search process.
Jane Wilkinson says. Thank you so much for this blog. I hope it is read widely. I am on a pastor search committee of a nondenominational church in essay Illinois. Language Introduction. Your words are incredibly on target. Our committee has made numerous comments about how sloppy some of the resumes are. Education Essay. We have tried to overlook the mistakes on the resumes but, frankly, the candidates we seem to favor are those that took the time to do a quality resume.
The sloppy resumes leave us with the memoir class thesis impression that the value education essay india candidate has a poor work ethic and prompt that he is too lazy to proofread read something he writes. I encourage pastors to education essay india, get outside readers to proofread their resumes. I hate to see an cause of domestic otherwise good candidate not be considered because of two or three pages of a document. Thom Rainer says. Thanks Jane. Value Essay India. Great input!
What about english essay those of value education essay us who have completed our seminary training, but the only ministry experience that we have had outside of an pastoral internship has been the various areas of service as a layperson. Some people have said not to illegal outline for research paper, include it because it was not “full time paid ministry”. Some have said to education essay india, include it. I have tried both ways and immigration outline for research paper after two years I am still searching for a full time vocational ministry opportunity. Well stated observations.
Another resource we’ve produced in Michigan is education, our SIMPLIFIED SEARCH TEAM TRAINING. We frequently recommend it to prospcetive pastors/staff to hear what we are recommending to search teams. A section of the training is on illegal for research paper “how to evaluate resume’s.” Maybe it will be helpful to your readers. Education Essay India. It is available at: http://bscm.e-quip.net/presentations/show/2974. Thom Rainer says. The worth of a ministry is not measured by its compensation level or whether you are compensated at ap lang prompt all. I strongly encourage pastors to include ALL ministry experience, paid and non-paid. Essay. Before I served as pastor, I asked the outline for research leadership of my church if I could give ten to education, twenty hours a week as a non-paid minister of evangelism and outreach.
They were happy for and effect violence me to do so and to give me the title I requested. Thom Rainer says. Steve Drake says. Thanks Dr. Rainer for value education india engaging such an important practical issue for ministers. If it isn’t true elsewhere, it is certainly true here: “You don’t get a second chance to make a first impression.” I have had students and cause and effect violence essay friends who have said, “I’m not sending resumes. God knows where I am, if He wants me to move, He can send the committee to me.” It is certainly true that God knows where we are, but if He is willing to use a donkey to get someone’s attention, I have no problem realizing He might just use a resume too.
More and more in our day, I think it would be good for ministry candidates to provide video footage online on YouTube or Vimeo sites to let the searching group have an “up close and personal” look at the candidate. Recently I was called by a committee asking for a recommendation of a young man. Everything I said about the candidate was already confirmed in his mind because he had read three years of the candidate’s blog. That church called the candidate and wonderful things are happening among them. Good post Dr. Rainer! I would also encourage folks to write a brief philosophy of ministry for education essay the resume. A church can learn a lot about a candidate from a brief but well worded statement describing one’s view of ministry and the church.
Now, for a list of things search committees do wrong… Robbie Perkins says. Jonathan…I agree. When I sent a resume to the church where I am currently serving as pastor I gave a “ministry philosophy” in and effect of domestic violence essay the form of value essay a cover letter. Dr.
Rainer… you mentioned a perceived priority in the listing of info on a resume, is there an order that you might recommend? Thom Rainer says. My preference is to provide brief biographical information first, like date of introduction birth and india place of birth. Within the memoir bio, I note my family members, including how long I have been married and the age of my children if they aren’t adults. Education India. Second, I provide a brief ministry and doctrinal statement.
Third, I note my education, not because of its priority but because readers expect it near the top. I then note my ministry experience and then secular experience. Miscellaneous items like published works and denominational experience go near the last, followed by paper, references. There is no best order, but those priorities are my preference and most common on the resumes I see. I have my resume’ in almost the same order you described here. Education Essay. I have also reworked my resume’ with consideration given to outline for research paper, the advice you provided in this article. All of the information in question covers two pages.
I also provide a third page that lists four references. I wish I could post it on india here to violence, let you see it, as I have put a lot of essay india work into organizing it. But I am wondering if it is english introduction, too long. Some have given me the essay india advise that pastor search committees do not really spend a lot of time pouring over resumes. So I should just keep it short and world history essay sweet by education india, providing just the nuts and bolts; just grab their attention without providing the detail I have given. So how do I find a happy medium here? Thom Rainer says. Most of the pastor resumes I see are 4-5 pages. The search committees tell me they do like the detail as long as it is not obvious fluff and filler. Thom Rainer says.
See my blog on October 3, 2011 where I address that very issue. Thanks. Robbie Perkins says. Thanks Dr. Memoir Class Thesis. Rainer. Jim Orchard says. A little off topic but related, search teams how about a little email letting us know you have received the education essay resume and then if you have decided to drop our resume from the list let us know with a note saying thank you for and contrast texting your interest so we can move on education essay with our search for a church. Thom Rainer says. Thanks. See my blog of October 3, 2011 where I address that matter to search committees. Sam Loveall says.
Dr. Rainer, here’s a tip for your readers that you didn’t include – – be sure to fill in all the blanks. During a search for a new youth minister, we received a resume that began with a cover letter (that I very much wish I had kept.) The letter writer went to great lengths to explain just how God had been leading this young man to our congregation. Memoir. Intense prayer, advice from others, deep soul searching – – things like that. I wish I could remember the exact words of the “climax” sentence of the letter, but it went some thing like this: “I am convinced that God has great things planned, and I look forward to india, speaking with you about serving with (church name) as we seek His further will for…” I’m surprised to hear you say to include a family section on ap lang analysis essay prompt your resume. Coming to the ministry from the business world (where I was a hiring manager) I would never have thought to include info about family since that is one thing you most definitely would not put on a resume for a secular job. Also, I hope that when you work with churches you remind them that this is value education india, a two-way street and they are under scrutiny by potential pastors just as the candidates are under scrutiny by them. I’ve had churches contact me seeking a resume who failed to provide any information or very little information or sloppily presented information and and contrast vs. calling essay the message this sends is that they think they are so wonderful that anyone would be blessed to be their pastor.
As true as that may be, I would have no way of knowing how good they are by the info they make available and how they present it. Thanks for these tips and please take it the right way when I say that I hope I never have to use them. Sometimes, it’s hard for pastors and value education essay india other ministry professionals to view their calling in job terms. But, at least one person on a Search Committee is going to compare and contrast texting vs. calling essay, be a business person and are accustomed to value essay, seeing professional resumes. They are going to essay introduction, assume that your resume indicates how one will run their church and value education india lead them spiritually. Will they be able to count on english language essay introduction you to handle things professionally, when someone confesses an addiction problem that would ruin their standing in the community? Will you professionally help families who have been in bitter disputes for years, when a loved one dies? Many churches are worried about value india decline and want to know if you are able to lead them toward spiritual and numeric growth.
Does your resume give them confidence you can? Do you have any great online or other resources to help pastors develop a ministry resume or portfolio? Great stuff. Thanks, definitely brought clarity to a foggy situation. Steven Zeigler says. I desire to be a worship leader. I have had no paid positions. I have only and effect essay, worked with two pastors and have done three years of value india mission work in the U.S. Practice History. God has put his hand on me to be a worship leader.
I am working 36 hours a week to support my family of four and I am age 47 now. I have not gone to bible college. I have had formal training for value education five years on organ and class thesis I have four years of education essay india performance with my college I attended many years ago. I have helped lead worship for five years at a preivously attended church and english essay sang on the choir, yet it has never been a paid position. I now serve on the choir with the value education essay Church I am attending. I have attended a worship school with Steve Swanson. Not a college. I have asked my pastor to compare texting, work with him, yet he has never called me or asked to come. My pastor has said, he agrees that God has a call on my life for value education essay india pastor of worship.
Where should I start and what should I do to apply for this position? I do believe God has opened this door for me and I have prayed. I have called the world history church to ask questions about the position. Anything above that, I am unsure what to do. Please help.
Mark Carlton says. Why do Southern Baptist churches focus so little on Singles’ ministry? With the adult population in the US at value education india more than 50% single, why do churches seem to disregard singles? I live in a city with over a million population and not one Southern Baptist Church has a strong singles ministry. Southern Baptist used to at least have a large singles conference once a year at memoir class Ridgecrest but that conference has significantly dwindled while the value education essay india singles population has grown substantially.
The church is practice world essay, losing its influence because this segment of the population is being ignored.
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150 More Funniest Resume Mistakes, Bloopers and education india, Blunders Ever. Cause Violence Essay. And all of these really happened. Don’t miss the Top 10 at the bottom. Enjoy! From CareerBuilder.ca’s study via Mainstreet.com: Resume delivered in a balloon A four-page resume detailing every position and volunteer job a person has ever had since he was 12 Each line had one bold word that formed a “hidden” message about how great the value education essay, applicant would be for the position [The resume was] Scrawled in ap lang analysis prompt pencil on essay, butcher’s paper Listed “Have flown on a corporate jet” as a notable achievement A resume etched into a wooden cutting board Many small teddy bears and daisies adorned the edges of the pink paper (used for practice world essay, the resume) Listed “Worked with my dad building things. Worked with my mum cleaning the house,” as past experience. From Business Insider’s HR Execs’ 13 Most Common Resume Blunders: “Extensive experience in pubic financing.” “Please find the value education, attached resume that highlights all my kills.” From CareerBuilder.com’s 2012 Study of Outrageous Resume Mistakes: Candidate called himself a genius and essay, invited the hiring manager to value education, interview him at his apartment. Candidate applying for a management job listed “gator hunting” as a skill.
Candidate specified that her resume was set up to be sung to practice world history, the tune of essay india, “The Brady Bunch.” Candidate’s resume had a photo of the history, applicant reclining in a hammock under the headline “Hi, I’m _____ and value education essay, I’m looking for a job.” Candidate listed “to make dough” as the objective on the resume. Language Essay. Candidate applying for an accounting job said he was “deetail-oriented” AND spelled the essay, company’s name incorrectly. From Huffington Posts’s 21 Funny Resumes Cover Letters: Actor’s resume specified a role in “The Departed” directed by of domestic Martin Scoresissers . Candidate listed experience as a “Marijuana Dealer and Nefarious Dude” “Objective: Ideal position would be businessman, with $18,000 to $250,000 in value education salary” “Previous Work Experience: Skateboarder from 1980’s to present time. Job duties include hanging out with friends, drinking, smoking, doing tricks such as ollying” Work Experience: “fileing files” “I’m fresh our [sic] of university with a childish sense of wonder and 100RPM sense of memoir class thesis, drive.” Hobbies: Eyebrow tweezing. From CareerBuilder.com’s 2013 Study of Outrageous Resume Mistakes: Resume didn’t include the candidate’s name. Resume listed the candidate’s online video gaming experience leading warrior “clans,” suggesting this passed for leadership experience. Resume included time spent in value education jail for assaulting a former boss.
Resume listed the analysis essay, candidate’s objective as “To work for someone who is india not an alcoholic with three DUI’s like my current employer.” Resume consisted of one sentence: “Hire me, I’m awesome.” Resume was submitted from a person the company just fired. Resume included pictures of the world essay, candidate from baby photos to value india, adulthood. On the job application, where it asks for your job title with a previous employer, the applicant wrote “Mr.” From AskReddit’s What Is The Most Unique/Outrageous Thing Someone Has Put On A Resume: (Someone commented: “Reading this thread just boosted my hopes of employment by like 200%”) Under ‘Have you ever been convicted of a felony’: “Yes Arson. Will explain in ap lang interview.” “One applicant tried to make an value education essay india impression by using four different fonts, three ink colors and a variety of language essay introduction, highlighting options on her résumé” Last job: Plumber. Reason for leaving: “Couldn’t plumb.” “I received one that was 5 pages long once.
The reason why it was that long was because when she put down that she worked at value education essay india [pizzeria name] as a “Pizza Maker” she listed each step of making a pizza as a separate job duty” “I was interviewing a guy, and I asked him a question about his Master’s degree he had on his resume. Ap Lang Essay Prompt. His response? ‘Oh I don’t have my Master’s degree yet I just plan on getting it someday.'” Under skills: “calculator on sight” Under management experience: “Dungeon Master” “A guy that just sent in a 8.5×11″ photo of him standing next to a limousine. No explanation given.” “An applicant listed “sarcasm” as a hobby/skill/interest. Essay. He got the job One of the best employees I’ve ever had.” “My biggest hobby is dishwashing” “I have had experience in logic programming, basic software creation, bear wrestling , and am fluent in C++.” “I was handed a CV which said ‘one of the UK’s top mountaineers praised my stamina'” “He lists one of practice, his qualifications as fluent in English with 20 years of value education essay, experience he lists his age as 19.” “Guy wrote his entire resume and and effect violence, application IN RHYME.” “I enjoy doing repetitive things like filing and photocopying” Job Experience: Hymen Checker on essay, Australian Sheep Farm. “When I asked him about cause and effect of domestic violence essay, it he said he just wanted to see if people actually read his resume.” Wage desired: “menemum” “I once received a resume that discussed, in great detail, a car accident the candidate had been in. It even included a diagram that showed where each passenger had been sitting.” “A mom came in value education with her son to fill out a job application. And Effect Of Domestic Violence. She turned it in for him as well as filled in everything for him. Under the “Other” portion she wrote ‘I am the oldest of three kids so I know how to be in charge.'” “I had a guy apply for a position at my work and on value, his application in the sex box he put ‘yes please’.” “Being on the cover of 2006 Time Magazine.” (when it was a computer with the word ‘You’ on screen) Interests: “eating, smoking, smoking weed, playing cod.” “Someone handed me a seven page resume, with a title page.
Each page had different fonts and dbq ap world essay, margins, and on the fourth page the margin started right in education india the middle of it. Not to mention that for most of cause and effect violence, it, she wrote her job experience, pressed enter about value education, 16 times, and then put her next job.” Achievement: Master of texting essay, Marital Arts (it was a kid) “A dude included his personal website URL, which had rantings about beating women and essay india, the elderly.” “Someone applying to ap lang analysis essay prompt, my friend’s lab had noted his email was ‘[email protected]'” “The guy had an essay entire section devoted to analysis, gaming achievements. Where a normal person might have “Volunteer Experience” or something of that nature, he had “Gaming achievements”. Everything from india, WoW guild to Tetris High scores.” “Had a friend interviewing for a graphic arts position. One of the ap lang analysis essay, pieces in the interviewee’s portfolio, was actually one of the interviewers’ old projects.” (Ouch!) “One day a young man came in and dropped off his resume. Apparently, he was a rapper and value essay, a skateboarder. On his resume, he had listed: Hobbies- Raping and scating.” “I also had someone upload a resume to our HRIS database. When I opened the file, it was just a camera phone self-shot of himself staring into of domestic violence essay, his bathroom mirror.” “Applicant didn’t include any contact information, other than a Twitter account.” “An applicant for an internship in my office concluded his cover letter with ‘And that’s why I would make a great addition to the Burger King family.'” Skills: “Can make perfect velociraptor call.” “Had someone put on their resume they were able to cook minute rice in 58 seconds. Value Education India. I laughed because I’ve seen this on the internet dozens of times and knew that’s where he got it from.” “I was once asked if I had any unique skills.
Instead of saying I apprenticed as a locksmith for a summer, ‘I’m really good at picking locks.’ Did not get that job.” Best followup comment: “Well you’re still going to get in essay prompt anyway.” ” I knew a girl who ended up in value a relatively popular viral video that was pretty embarrasing. I proofread her resume and noticed she put it on illegal immigration paper, it.” “Someone writing the entire résumé without a single capital letter.” “cleaned up after every shift” ( but without the ‘f’) “Visa to work in value essay india the US?” Applicant wrote “no, Mastercard.” Applicant listed the address of each company she worked for and contrast texting vs. calling, but none of their names. “I always staple at exactly a 45º angle.” “A 17 year old kid who applied for value essay india, a camera operator job and had multiple pages on his resume listing all the language essay, DVD commentaries that he’d listened to.” “On two separate occasions people have come into my office, handed the receptionist their resumes and asked for her to value essay india, make a copy because it was their ‘last one.'” “interviewed a young mechanical engineer major who listed training her cat to use the english language essay introduction, toilet as an essay india achievement” “a guy put his P90x certification under certifications on memoir thesis, an IT resume” “At the end of value education essay india, every line he would write either a superscript plus or a superscript minus.” “First thing on compare and contrast texting vs. calling essay, this guy’s job history was ‘World Class Amigo'” “I don’t need maternity leave like a woman. I don’t go shopping on my lunch breaks like a woman. I don’t have mood swings once a month like a woman. Essay. I don’t gossip about people like a woman.” On a cover letter : “I had a dream last night, and GOD told me that I will get this job, and memoir, this is what is india right for me” “Speaking in English was listed as a hobby.” “He had no college education, so in the space on the application for college and on his resume he put the essay, Latin for value education essay india, “no college education.” It sounded very fancy and prestigious in cause and effect of domestic violence essay Latin, so he got the job.” “He took the advice of fitting your resume on essay, one page a little too seriously. It started at size 14 font and worked its way down to a size 8 at the bottom like an optometrist chart. Just a huge block of unreadable text.” “One guy went on ap lang analysis essay prompt, length about how he helped build the value education essay, international space station as an intern. Cause And Effect Of Domestic Violence. Did he mean helped in it? No, he claimed to literally be on value education india, the floor while the pieces were being manufactured and was sent to various countries to oversee the process all during a summer internship.” “Please do not call my last employer as a referencehe was the owner of the small company I worked for, and ap lang, I was involved with him. His wife learned of this.
I was fired to save his marriage, and education india, he will not give a fair recommendation. Please feel free to contact [an employment 6 years prior before being unemployed for 4 years].” “I was working at Staples at the time and english language introduction, someone dropped off a resume at the front. Glancing at it, near the value essay india, top of the resume it said, ‘I would be very grateful for thesis, an opportunity to work in education essay india your store. If I could choose any department to work in, it would be deli.'” “My father worked in vs. calling essay management at large power plant construction projects. He once received a 15 page resume. It contained diagrams of equipment the applicant had used and diagrams of equipment he has seen in use.
All the diagrams had their components labeled, using names that he made up since he did not know most of the correct terms.” “I put ‘buffalo enthusiast’ figuring nobody ever reads my hobbies sections. First question in my last interview, ‘what is a buffalo enthusiast’?” “Years ago I was a manager at a telemarketing office. A mid-40’s woman came in with a resume that had been made with pencil crayons. It had flowers and rainbows drawn on it. Every other letter was done in different colours. Needless to say she is now in management.” Skills: Magic the Gathering “Corporate relations director at his fraternity” “A guy had put down that he could pull off a 95% world record pace at jumping jacks.” One graphic designer candidate’s portfolio was was filled with projects done at value essay her last job, by other people . “On his resume was a huge picture of his face. Cause And Effect Of Domestic Violence Essay. It took up at value education least 40% of the page. Memoir Thesis. Under his face were his credentials in what must have been at least 8pt font size.” “’10 years Java experience’ In 2002.” (Java was launched in 1995) Under his computer skills section: Tiger Woods Golf “Applicant for education essay, retail management job put on his résumé he won a medal in Taekwondo in illegal outline paper the 1988 Olympics. A quick Internet search revealed that he did not.” “a woman left a resume with her head shot on the back and one of her skills was ‘riding a bicycle’.” “My manager handed around a resume that someone had submitted where it was painfully obvious that the applicant had looked up every other word in a thesaurus and value, chose the compare and contrast vs. calling, longest potential synonym he could find.” “I had two guys apply for laborer/operator positions, they sent one email with both of their contact information and india, resumes attached.
The resumes were identical, except for the names. “ Last job: owned own business. Reason left: fired. “a resume that included a picture in the upper left hand corner of the applicant. The applicant was sitting on her bed in umbros, eating a sandwich.” “This girl emailed me her resume with the illegal for research, name Addison Sheffield, I replied that is a great name and I love the Cubs and she was like, oh, actually my name’s Caroline but I do that to get more resume looks.” (Addison Sheffield are two of the essay, streets bordering Wrigley Field in Chicago) Why do you want to illegal immigration paper, work with us? “2 get dat $$$.” “Not a child molester.” Skills: “Yeah I got ’em” Main skills: creativity, bravery, arrogance, cleverness and honesty. Special skills: “good with money, good working alone.” Reason for leaving last job: “fired for stealing.” “Detail-orientad” Career achievements: “having an Asian girlfriend” “this guy sent his resume to where I work He attached a photo of himself posing in a tiny bathing suit holding a puppy.” Accomplishments: “I am a bomb expert” (foreigner applying for an engineering job in value education essay india the US) “Someone applied to our startup with our company in his resume. Apparently he was telling other employers that he worked here and and contrast texting vs. calling, forgot to take it off.” “a kid wrote under Accomplishments: his mother had once interviewed famous serial killers.” “Can summon sea creatures within 15 feet of water (boiling or room temperature).” Under skills: “Walking I am very good at this.” “I had a lady apply for a sales rep position and the first line in her resume was a career objective that stated that she wanted a career in nursing.” “guy had every line in his resume underlined” Under “areas of expertise”: “reliance on god for value education india, optimal results.” Under skills and and contrast vs. calling, accomplishments for value education essay india, a hotel accounting job applicant. “Over 3,000 cremations in 4 years.” “invented Gmail before Google.” Reason for leaving: “Husband was boss, left me for waitress.” Under the “Experience” section: Sexual Assault Advocate. “I want to be an astroaught but think working in compare texting a call center will help me gain confidence in essay talking to ap lang analysis, mission control from education essay, space” References: “God” Hobby: “petting my dog” Traits: “good looking” “One resume at my work replaced the entire cover letter with a stock photo of a sunset.” “A copywriter called us and asked if we had an FTP to upload her resume to because her cover letter wasn’t attaching to language, email correctly. It was an MP3 of her reading her cover letter.” Strengths: “Really good at value india Lego” Weaknesses: “Bullets” “Fluent in Ebonics” Other Qualifications: “Have only missed 3 child support payments.” “A 398-page resume with links to an African man’s musings on life and how Gold Eagles have secret powers to save us.” A young woman wrote her resume in black marker on her bare back and sent a picture of it (Dana Leavy-Detrick) “He proudly presented a worn index card written in dull pencil to represent what I was to accept as his resume. Only the front of the memoir thesis, card was filled.” (HRMorning) Candidate sent his resume in value the form of an oversize Rubik’s Cube, where you had to push the tiles around to align the resume. Language Essay Introduction. (He was hired!) (Jobs.aol.com) “I’m the best in value the world at: Reading Comprehension” (Buzzfeed) “I’m the best in essay the world at: Chivalry” (Buzzfeed) “I can do 75 push ups in a row” (For an IT job and he got hired!) (AskReddit) Candidate’s cover letter talked about her family being in the mob. (CareerBuilder.ca) “If there was one word to describe me it would be ‘Da-bomb’.” (HuffPost) Under hobbies/interests: “Simulating earthquake by shaking table” (AskReddit) “I’m a natural winner. Before I was even born I won a competition against millions of fellow spermatozoids” (AskReddit) “My English fluent.” (AskReddit) Applicant listed experience as a “Cock, Food Prep/Pizza Maker” (HuffPost) Candidate claimed to be able to speak “Antartican” when applying for value essay india, a job to work in Antarctica. (CareerBuilder.com) “I promise to make your store 10000000000000000000000000000000000 dollars” (HuffPost) Have you ever been convicted of compare essay, a felony? “Not yet” Reason for leaving last job: “Mexico” “I was looking for a job, and I wanted to india, learn Microsoft Word on practice history essay, the computer.
So I was messing around with it one day, and my husband at value education india the time was in the room, arguing with me. So I wrote “F YOU” really big in different colors and fonts, playing around, learning [the program]. I saved it under ‘doc1.’ “A couple of days later, I completed my resume on Word and saved it as “res1.” Well, I was talking to this woman about a job, and analysis, we hit it off. She said to send my resume, so I did. Value Education Essay. A day later she wrote back, “Same to language essay, you.” I didn’t know what that meant until I opened the attachment I sent her and realized I sent her ‘doc1’ instead of ‘res1.'” Subscribe to JobMob via RSS or email and education india, follow me on Twitter for the best job search stories ever. Job Search Expert, Professional Blogger, Creative Thinker, Community Builder with a sense of humor. I like to help people. Top 10 Funniest Job Horror Stories. Most Funny and Painful Embarrassing Moments At Work. Outline. Funny! Also really happened#8230; I started in value education essay india recruiting in 1996 and cause and effect of domestic violence, back then we were advertising in a global paper for value essay, the airline industry.
One day we received a hand written letter from compare, a little island far far away, which I never heard of. He didn#8217;t include a resume, just a motivation letter, in which he informed us that he was interested and continued with mentioning all his family members. He had a story why his dad liked him, a short story from his brother why he should get a job, another story from his cousin who also liked him, etcetera. Hilarious! Thanks for education india, sharing, Jacco. Analysis Essay Prompt. Funn-eeee. Yes, that IS the currect spellling, wut are yew tawking abowt? Never just rely on #8216;spell-check#8217;! Family and I split our sides about so many, but favs are: #8216;Teach the cat to education essay, use toilet#8217;; #8216;Clean up after every #8216;shift#8217; (Minus #8216;F#8217;), and #8216;Felony: Yes #8230; Arson (Will explain in interview)#8217; Yikes! Also have a couple of compare essay, doozies I#8217;ve read: 1: #8216;References: None; have left trail of destruction in my wake#8217; (O-kaay!); 2: Read about military application, where interviewer wrote: #8216;This applicant snuck into the gene pool while the life guard was off duty#8217;.
Yee-Ouch! Hilarious adds to education essay, the list, Florence. Thanks for that. Illegal Immigration Paper. Makes me wonder when the essay, US gonna catch up with China in global economic competition.The sampling of resumes explains part of the cause of domestic, surprises. No wonder many technology companies hijacked H1-Visa to get cheaper labor from value education, India and english, China #8220;not enough qualified workers from the US.#8221; No doubt recruiters see many mistakes from English Second Language (ESL) job seekers and essay, poor translation, but the vast majority of the blunders here are too subtle or culture-related. [#8230;] Profession.hu cikkeben 13 olyan furcsa vagy eppen meghokkento reszletet ismertet, melyeket a Job Mob karrierportal mazsolazott ki az eletrajzokbol. Rekeszizmokat ellazitani, mielott hozzakezd [#8230;] [#8230;] Instructions: According to recruiters, one of the memoir class, biggest mistakes candidates make is not following application instructions. Heed any special resume requirements in job [#8230;] [#8230;] to recruiters, one of the biggest mistakes candidates make is value not following application instructions. And with about 150 applications received for english essay, every job [#8230;] [#8230;] 150 More Funniest Resume Mistakes, Bloopers and Blunders Ever [#8230;] [#8230;] follow-up, 150 More Funniest Resume Mistakes, Bloopers and Blunders Ever, had this nugget: “Someone applying to my friend’s lab had noted his email was [#8230;] 28928 followers 2496 likes 2261 followers 1361 followers 1660 JobMob Insiders 881 posts 11604 comments.
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SAT / ACT Prep Online Guides and Tips. Did you think you were all done pouring out value india, your blood, sweat, and tears in written form for world history, your personal statement, only to be faced with the value “why this college” supplemental essay? This question seems simple on its face, but is in fact a crucial and ap lang analysis essay potentially tricky part of many college applications. What exactly is the “why us” essay trying to understand about you? And how do you answer the india question without falling into its many pitfalls or making any rookie mistakes? In this article, I’ll explain why colleges want you to be able to explain why you are applying. I'll also talk about how to generate and compare texting vs. calling essay brainstorm topics for education, this question, and immigration outline for research paper how to make yourself sound sincere and committed. Finally, I’ll throw in some “why this school” essay dos and value education don’ts. Why Do Colleges Want You To Write a “Why Us” Essay? College admissions officers have to read an incredible amount of dbq ap student work to put together each winning class.
So trust me when I say that everything they ask you to write is meaningful and important. The purpose of value this essay goes two ways. On the one hand, seeing how you answer this question gives admissions officers a sense of whether you know and value their school . On the illegal immigration for research other hand, having to verbalize why you are applying is value education essay india a chance for you to ponder what you want to get out of your college experience , and whether your target schools fit your goals and memoir aspirations. What Colleges Get Out of Reading Your Why This College Essay. Colleges want to check three things. First, that you have a sense of what makes their college different and special. Do you know something about the school’s mission, history, and values? Have you thought about their specific approach to essay, learning? Are you comfortable with their traditions, the feel of their student life? Second, that you will be a good fit for the institution. Where do your interests lie?
Do they correspond to this school’s strengths? Is there something about you that meshes well with some aspect of the cause and effect of domestic violence college? How will you contribute to education essay, college life? How will you make your mark on campus? And third, that this institution will, in turn, be a good fit for you.
What do you want to get out of college? Will this college be able to provide that? Will this school contribute to your future success? What will you take advantage of on campus – academic programs, volunteer/travel opportunities, internship hookups, extracurricular clubs, etc.? Will you succeed academically? Is this school at the right rigor and pace for your ideal learning?
What You Get Out of Writing Your Why This College Essay. Luckily, in the process of articulating these answers, you will also benefit in several ways. Finding specific programs and texting opportunities at schools that you are already happy about will give you a grounded sense of direction for when you start school. At the same time, by describing what is great about essay india schools that are low on your list, you'll boost your enthusiasm rather than feeling these colleges are lackluster fallbacks. Ensuring You're Making the Right Choice. At the same time, writing the why us essay can be a moment of cause of domestic essay clarity. It's possible that you won’t be able to come up with any reasons for education essay, applying to illegal immigration outline for research paper, a school. If the more research you do the india more you see that you won't fit, this may be a good indicator that this particular school is not for you. At the practice dbq ap world history essay end of your 4 years, you want to feel like this, so take your Why This College essay to heart.
The Two Different Kinds of “Why This College” Essay Prompts. The why this college essay is best thought of as a back and india forth between you and the college . This means that your essay will really be answering two separate but related questions: First, why us? This is where you'll explain what makes the school special in your eyes, what attracted you to world history, it, and what you will get out of the experience of going there. Second, why you? This is where you'll talk about why you’ll fit right in on education essay india campus, what qualities/skills/talents/abilities you’ll contribute to campus life, and how your future will be impacted by the school and its opportunities. Colleges usually take one of these two different ways to class, frame this essay , which means that your essay will lean heavier towards whichever question is essay favored in the prompt. So if the prompt is all about why us?, you'll focus more on waxing rhapsodic about the school. If the prompt instead is mostly configured as why you?, you'll dwell at length on your fit and potential.
It's good to and effect, remember that these two prompts are simply two sides of the same coin. Education India. Your reasons for wanting to apply to a particular school can be made to illegal for research paper, fit either of these questions. For instance, say you really want the chance to learn from the world-famous Professor X. A why us essay might dwell on how amazing an opportunity studying with him would be for you, and how he anchors the Telepathy department. Meanwhile, a why you essay would point out that your own extracurricular and academic telepathy credentials and education india future career goals make you an ideal student to essay, learn from Professor X, a renowned master of the value essay india field. Let me show you some real-life examples of illegal paper what these two different approaches to the same prompt look like. I hear the Rings of Power Department is really strong at that school too. Check out the Gandalf seminar on repelling Balrogs - super easy A. Why [this college]? Why are you interested in our school? Why is this college a good choice for you? What is it that you like the value education essay india best about our university?
Why do you want to go to our college? University of Michigan: Describe the practice history unique qualities that attract you to the specific undergraduate College or School (including preferred admission and dual degree programs) to which you are applying at the University of Michigan. How would that curriculum support your interests? Tulane University: Please describe why you are interested in attending Tulane. Tufts University: Which aspects of Tufts’ curriculum or undergraduate experience prompt your application? In short, “Why Tufts?” Wellesley College: When choosing a college community, you are choosing a place where you believe that you can live, learn, and essay india flourish. Generations of inspiring women have thrived in the Wellesley community, and we want to know what aspects of this community inspire you to consider Wellesley. We know that there are more than 100 reasons to choose Wellesley, but the “Wellesley 100” is and effect of domestic a good place to start. Visit the Wellesley 100 and let us know, in two well-developed paragraphs, which two items most attract, inspire, or energize you and why. (PS: “Why” matters to education, us.) Colorado College: How did you learn about Colorado College and essay why do you wish to value education, attend?
Oberlin College: How did your interest in Oberlin develop and what aspects of our college community most excite you? University of Richmond: Please choose ONE of the two essay prompts: (1) Sometimes asking the right question makes all the difference. If you were a college admission counselor, what essay question would you ask? Please craft and answer your own essay prompt – in violence, your response, reflect on what your chosen question reveals about you.; OR (2) Tell us about Spiders. Tell me all about. me. Why are you a good match or fit for us? What are you interests and how will you pursue them here? What do you want to study and how will that correspond to our program? What or how will you contribute?
Why you at our college? Why are you applying to our school? Babson College: One way Babson defines itself is through the notion of education india creating great economic and social value everywhere. How do you define yourself and what is it about Babson that excites you? New York University: Whether you are undecided or you have a definitive plan of compare and contrast texting study in mind, what are your academic interests and how do you plan to explore them at NYU? Bowdoin College: Bowdoin students and alumni often cite world-class faculty and value education essay india opportunities for intellectual engagement, the College’s commitment to the Common Good, and memoir thesis the special quality of life on the coast of Maine as important aspects of the Bowdoin experience. Education Essay India. Reflecting on your own interests and experiences, please comment on compare and contrast texting vs. calling one of the following: 1.) Intellectual engagement, 2.) The Common Good, or 3.) Connection to place. India. Kalamazoo College: In 500 words or fewer, please explain how Kalamazoo College’s approach to education will help you explore your ideas and interests both inside and outside of the classroom. Lewis Clark College: Lewis Clark College is a private college with a public conscience and a global reach. We celebrate our strengths in collaborative scholarship, international engagement, environmental understanding and entrepreneurial thinking.
As we evaluate applications, we look for students who understand what we offer and are eager to cause and effect of domestic essay, contribute to our community. In one paragraph, please tell us why you are interested in attending Lewis Clark and how you will impact our campus. Whitman College: Part of being a Whittie is living and growing as a unique individual within a supportive community. Value Education Essay India. These are words that we think describe much, though not all, of the and effect of domestic essay Whitman experience: Intellectually Curious - Northwest - Taco Trucks - Slam Poetry - Outdoorsy - Testostertones - Globally Engaged - Flag Football - Thesis Project - Wheat Fields - Intercultural - Encounters Program - One Acts - Organic Garden - 24/7 Library - Ultimate Frisbee - Collaborative Research - Playful - Semester in the West - Life of the Mind - Walla Walla - Whitman Undergraduate Conference - Interest House Community - Sweet Onions - Experiential Learning. Pick three of these words or phrases, or share with us three of your own, and explain how these terms resonate with or inspire you. How does this part of value education essay who you are relate to illegal immigration outline paper, joining the Whitman community? Sure, Ultimate Frisbee is cool, Whitman College.
But when I get to campus, I'm starting a quidditch league. How to value education india, Write a Perfect “Why This College” Essay. No matter how the english language introduction prompt is worded, this essay is a give-and-take of what you and the college have to offer each other. Your job is to zoom in quickly to your main points, and to use precision and detail to sound sincere, excited, and authentic. So how do you effectively explain what benefits you see this particular school providing for you, and what pluses you will bring to india, the table as a student there? And how can you do this best using the small amount of memoir class thesis space that you have (usually 1-2 paragraphs)? Let's now go through the process of writing the Why This College essay step by step. First, I'll talk about the prep work you'll need to do.
Then I'll go through how to brainstorm good topics, and the topics to avoid. Value Education India. I'll give you some tips on transforming your ideas and research into an actual essay. And Effect Of Domestic Violence Essay. And finally, I'll take apart an essay india actual Why Us essay to outline for research, show you why and how it works. Before you can write about a school, you need to value essay, know specific things about practice world history what makes it stand out and appeal to you and your interests . Value Essay. So where do you look for these? And how do you find the cause and effect violence detail that will speak to you?
If you’re going on college tours, you’ve got the perfect opportunity to value education essay india, gather info. Analysis. Bring a notepad with you, and write down: your tour guide’s name 1-2 funny, surprising, or enthusiastic things they say about the school any unusual features of the value education campus, like buildings, sculptures, layout, history, or traditions. Also, try to connect with students or faculty while you’re there. If you visit a class, write down which class and essay the professor’s name. Value Essay India. See if you can briefly chat up a student (in the class you visit, around campus, or in ap lang analysis, the cafeteria) and value essay india ask what they like most about the school, or what has most surprised them about being there.
Write down the answer! Trust me, you’ll forget it otherwise, especially if you do this in compare texting, multiple college visits. If you can’t get to the campus of your target school in real life, the next best thing is an online tour either from the value essay school’s own website, or from places like youniversitytv, campustours, or youtube (search [school name] + tour). You can also connect with students without visiting campus in person. Many admissions websites will list contact information for students you can email to ask one or two questions about what their experience of the school has been like. Or, if you know what department, sport, or activity you’re interested in, you can ask the compare and contrast admissions office to put you in value education, touch with a student who is involved with that interest. Soon, fully immersive VR campus tours will let you play in Minecraft mode, where you just build each school from compare texting, scratch brick by brick. If you have an essay interview, ask your interviewer questions about their experience at the school, and also about illegal immigration for research what going to that school has done for them since they graduated. As always, take notes.
If you have a chance to value essay, go to a college fair where your target college has sent reps, don’t just come and pick up brochures. Engage the reps in conversation and ask them questions about what they think makes the school unique, so you can jot down notes about of domestic any interesting details they tell you. Colleges publish lots and lots of different kinds of things, any of value india which is useful for cause and effect violence, research. Here are some suggestions, all of india which you should be able to find online. Brochures and course catalogs. Read the essay mission statement of the school – does their educational philosophy align with yours? Read through college catalogs. Are there any programs, classes, departments, or activities that seem tailor-made for value education, you in some way? Pro tip: these should be unusual in some way or different from memoir class, what other schools offer. For example, being fascinated with the English department isn’t going to cut it unless you can discuss its unusual focus, 1-2 exceptional professors, or the different way they structure the major that appeals to you specifically.
The alumni magazine . Are any professors highlighted? Does their research speak to value education essay, you, or connect with a project you did in analysis essay prompt, high school or for some extracurricular? Sometimes alumni magazines will highlight a college’s new focus or new expansion. Education India. Does the construction of a new top of the line engineering school correspond with your intended major? There may also be some columns or letters written by alumni that talk about what it’s meant to them to go to ap lang analysis prompt, this particular school.
What stands out about their experiences? The campus newspaper. Value Education Essay. Students write about the hot issues of the day, which means that the articles will be about the best and worst things on english language introduction campus. They will also give you insight into student life, into value education essay india, what opportunities are available, etc. The college’s social media. Your target school is most likely on illegal immigration outline for research paper Facebook, Twitter, Instagram, or other social media. Follow them to see what they are posting about. Exciting new campus development? Some professors in the news? Interesting events, clubs, or activities?
Wikipedia is a great source for value education india, learning details about the college’s history, traditions, and compare texting vs. calling essay values. You can also search interesting phrases like “What students really think about [your school]” or “[your school] student forum.” This will let you find for detail-heavy points of view, comments about specific programs or courses, and insight into student life. So what should you do now that you've done a bunch of research? Use it to develop connection points between you and your target school. These connections will be the skeleton of your essay. You now have on essay india hand all kinds of information, from your own personal experiences on campus, to your conversations with people affiliated with your target school, to what you learned from analysis prompt, campus publications, to tidbits gleaned from the essay india web. Now you have to sift through all of your notes to find the three to five things that really speak to you.
Take what you’ve learned about the school and link it to dbq ap world history, how you can plug into this school’s life, approach, and environment . That way, no matter whether your target school's prompt is more heavily focused on the why us or why you part of the give-and-take, you'll have an entry point into the essay. What should these three to essay, five things be? What should you keep in mind when you're looking for compare essay, the gem that will become your topic? Here are some words of wisdom from Calvin Wise, the Senior Associate Director of Admissions for Johns Hopkins University: Focus on india what makes us unique and why that interests you. Do your research, and articulate a multi-dimensional connection to thesis, the specific college or university. We do not want broad statements (the brick pathways and value education essay historic buildings are beautiful) or a rehash of the memoir thesis information on education our website (College X offers a strong liberal arts curriculum).
All institutions have similarities. We want you to practice dbq ap essay, talk about our differences. Time to find that diamond, amethyst, opal, tourmaline, or amber in the rough. Check Your Gems for value india, Color and Clarity. In other words, make sure that each of illegal immigration outline your three to five found things is something that your target school has that other schools don’t. This something should be seen from your own perspective.
The point isn't to generically praise the school, but instead to go into value education essay india, detail about why it’s so great for you that they have this thing. This something you find should be meaningful to the school and specific to you. For example, if you focus on academics (courses, instructors, opportunities, or educational philosophy), find a way to link them either to your previous work or to your future aspirations. This something should not be shallow and non-specific. Want to vs. calling, live in a city? Every city has more than one college in it. Find a way to india, explain why this specific college in and contrast texting essay, this specific city calls to you. Like pretty architecture? Many schools are beautiful, so dwell on why this particular place feels unlike any other.
Like good weather, beach, skiing, some other geographical thing? There are many schools located near these places, and they know that people enjoy sunbathing. Either build a deeper connection or skip these as reasons. Convert Your Gems Into Essay Topics. Every Why This College essay is going to answer both the why us and education the why you parts of the back-and-forth equation. But, depending on english essay introduction which way your target school has worded its prompt, you will lean more heavily on education essay that part. This is why I’m going to split this brainstorming up in dbq ap world, two, to go with the “why us” and “why you” types of education questions. Of course, since they are both sides of the compare and contrast texting same coin, you can always easily flip each of these ideas around in order to value education, have it work well for the other type of prompt . For example, a “why us” essay might talk about how very interesting XYZ interdisciplinary project is and how it fits well with your senior project.
But a “why you” essay would take the same idea but flip it to say that you learned through your senior project that you deeply value an interdisciplinary approach to violence essay, academics, which makes you a great fit for this school and essay its own commitment to cool interdisciplinary work as evidenced by project XYZ. Project XYZ had many moving parts, one of which for some reason was a giant labyrinth. How a particular program of study/internship requirement/volunteer connection will help further your specific career goals. The school's interesting approach to your future major (if you know what that will be), or to a major that combines several disciplines that appeal to you and fit with your current academic work and interests. How the school handles financial aid and the infrastructure setup for low-income students, and what that means for you in terms of opening doors. A story about how you became interested in language essay introduction, the school (if you learned about it in value education, an interesting way).
Did it host a high school contest you took part it? Feature a visual or performing art that you enjoyed and that you also do? How you overcame an and effect of domestic violence essay initial disinterest in value, the school (if you minimize this first negative impression). Illegal For Research Paper. Did you do more research? Interact with someone on campus?
Learn about the school’s commitment to education, the community in some way? Learn about interesting research being done there? A positive interaction you had with current students, faculty, or staff, as long as this is more than just Everyone I met was really nice. Analysis Essay. An experience you had on the campus tour. Super passionate tour guide?
Interesting information that surprised you? Did something happen to essay india, transform your idea about the school or campus life (in a good way)? Interesting interdisciplinary work going on and contrast vs. calling at the university, and how that connects with your academic interests/career goals/previous high school work. The history of the value education india school, but only if it’s meaningful to you in some way. Has the school always been committed to fostering minority/first generation/immigrant students? Was it founded by someone you admire? Did it take an unpopular, but, to you, morally correct stance at some crucial moment in of domestic, history? An amazing professor that you can’t wait to india, learn from.
Is there a chemistry professor whose current research meshes with a science fair project you did? A professor who’s a renowned scholar on your favorite author/genre? A professor whose book on analysis essay prompt economics finally made you understand the most recent financial crisis? A class that sounds fascinating, especially if it’s in value essay india, a field that you want to major in. Extra bonus points if you have a current student on and effect violence essay record raving about it. A facility or piece of value education india equipment that you can’t wait to work with or in, and that doesn’t exist many other places. A specialty library that has rare medieval manuscripts? An observatory? A fleet of boats? A required curriculum that appeals to you because it provides a solid grounding in the classics, it shakes up the practice history traditional canon, connects all the students on campus in one intellectual project, or is taught in value education, a unique way. If the school can boast eight NASA aircraft of its own, I'd try to fit that in somewhere too.
Do you want to continue a project you worked on in high school? Talk about how/where in the current course, club, and program offerings this work would fit in. Why will you be a good addition to the team? Have you always been involved in english, a community service project that is already being done on campus? Write about integrating life on essay india campus with events in the surrounding community. Are you going to keep doing performing arts, music, working on the newspaper, or something else that you were seriously committed to in high school?
Discuss how excited you are to join that existing organization. Are you the perfect person to take advantage of an internship program (because you’ve already worked in this field, because you were exposed to english essay introduction, it through your parents, because you’ve done academic work that gives you some experience with it)? Are you the ideal candidate for a study abroad opportunity (because you speak the language of the country, because it’s a place where you’ve worked or studied before, because your career goals are international in education essay, some respect) Are you a standout match for an undergraduate research project (because you will major in analysis essay, this field, because you’ve always wanted to work with this professor, because you want to education essay, pursue research as a career option)? Is there something you were deeply involved with that doesn’t currently exist on campus? Offer to start a club for immigration, that thing. And I mean club: you aren’t going to magically create a new academic department, or even a new academic course, so don’t try offering that). If you do write about this, make double, triple sure that the school doesn’t already a club/course/program for essay, this interest. Immigration Outline Paper. What are some of the programs and/or activities you would plan to get involved with on education india either campus, and what unique qualities will you bring to them? Make this a mini version of a personal statement you never wrote: use this essay as another chance to show a few more of the skills, talents, or passions that don’t appear in english language introduction, your actual college essay.
What’s the runner-up interest that you didn’t write about? What opportunity, program, or offering at the school lines up with? This is definitely the time to essay, open up about your amateur kinetic art sculptures. Possible Topics For a College That’s Not Your First Choice. If you're writing about a school that you’re not completely psyched about, one way to sidestep the issue is to ap lang analysis, focus on what getting this degree will do for india, you in the future. How do you see yourself changing existing systems, helping others, or otherwise succeeding?
Alternately, discuss what they value academically, socially, environmentally, philosophically and how it connects with what you also care about. A vegan, organic, and cruelty-free cafeteria? A relationship with a local farm or garden? De-emphasized fraternity involvement? Strong commitment to environmental issues? Lots of opportunities to immigration for research paper, contribute to the community surrounding the essay school? Active tolerance and inclusion for various minority groups? Try to find at least one or two things that you’re excited about for all the illegal immigration for research paper schools on education your list. If you can’t think of a single reason why this would be a good place for illegal immigration, you to essay, go, maybe you shouldn’t be applying there. Don’t write about the school's size, location, reputation, or the weather, unless it is the only one of its kind. For example, anyone applying to the Webb Institute, which has less than 100 students should by practice dbq ap all means, talk about a preference for tiny, close-knit communities.
On the other hand, schools in sunny climates know that people enjoy good weather - but if you can't connect the india outdoors with the college itself, think of something else to say. Illegal Paper. Don’t talk about your sports fandom. The I can see myself in purple and white / maroon and value gold / [any color] and [any other color] is an overused idea. After all, you could cheer for compare texting, the team without going to the school. Value Essay India. So unless you are an athlete or an aspiring mascot performer, or have a truly one of a kind story to tell about ap lang your link to india, the team, try a different tack. Don’t copy description from the college's website to tell admissions officers how great their college is. They don’t want to hear praise; they want to hear how you connect with their school.
So if something on the college brochure speaks to you, explain why this specific detail matters to you and how your past experiences, academic work, extracurricular interests, or hobbies connect with it. Don’t use college rankings as a reason for dbq ap, why you want to go to a school. Of course prestige matters, but schools that are ranked right next to each other on the list are at about the value education india same level of prestige. What makes you choose one over violence the other? If you decide to write about a future major, don’t just talk about what you want to study and why. Make sure you also explain why you want to study this thing at this particular school . What do they do differently that other colleges don’t? Don’t wax poetic about the school’s pretty campus. “From the education india moment I stepped on your campus, I knew it was the place for me” is another cliche – and another way to say basically nothing about why you actually want to go to language introduction, this particular school.
Lots of india schools are pretty, and many are pretty in analysis essay, the exact same way. Pop quiz: this pretty Gothic building is on what college campus? Yup, that's right - could be anywhere. When you've put together the ideas that will make up your answer to the why us question, it's time to build them into a memorable essay. Here are some tips for doing that successfully: Jump right in. The essay is short, so there's no need for value education essay india, an introduction or conclusion. Spend the first paragraph delving into your best one or two reasons for applying. Cause Of Domestic Violence. Then, take the value education essay india second paragraph to memoir class, go into slightly less detail about reasons 2 (or 3) through 5.
To thine own self be true. Write in your own voice and education be sincere about what you’re saying. English Language Essay Introduction. Believe me, the reader can tell when you mean it and when you’re just blathering. Details, details, details. Mention by name specific classes, professors, clubs and activities that you are excited to be a part of.
If you plan on attending if admitted, say so. Colleges care about the value education india numbers of acceptances deeply, so it may help to know you’re a sure thing. But don’t write this if you don’t mean it! Don’t cut and history paste the same essay for every school . Value Essay India. Either al least once you’ll forget to dbq ap essay, change the school name or some telling detail, or else your vague and cookie-cutter reasoning will sound bland and forgettable. Cookie cutters: great for education, dough, terrible for college applications. Example of a Great “Why This College” Essay. At this point, it'll be helpful to take a look at a “why us” essay that works and figure out what the author did to create a meaningful answer to memoir class thesis, this challenging question. It was on my official visit with the cross country team that I realized Tufts was the perfect school for me. Our topics of conversation ranged from Asian geography to efficient movement patterns, and everyone spoke enthusiastically about what they were involved in on campus. I really related with the guys I met, and value I think they represent the essay passion that Tufts' students have.
I can pursue my dream of education being a successful entrepreneur by joining the Tufts Entrepreneurs Society, pursuing an Entrepreneurial Leadership minor, and taking part in an up-and-coming computer science program. Interaction with current students. James writes about hanging out with the vs. calling essay cross country team and sounds excited about meeting them. “I’m a great fit.” He uses the conversation with the cross country guys to talk about his own good fit here (“I really related with the value education essay guys I met”). Why the analysis prompt school is special. James also uses the conversation as a way to show that he enjoys the variety of opportunities Tufts offers (their fun conversation covers Asian geography, movement patterns, other things they “were involved with on campus”). Taking advantage of this specialness. He doesn’t just list things Tufts offers, but also explains which of them are of specific value to him. He’s interested in being an entrepreneur, so the education essay Tufts Entrepreneurs Society and the Entrepreneurial Leadership courses appeal to him. Awareness of what the school is up to. Finally, James shows that he’s up on the latest Tufts developments when he mentions the new computer science program.
You can see more great “Why this school” essays written for Tufts on their website. The “why this college essay” is of domestic violence looking for three things: To make sure you understand what makes their college different and education india special To make sure you will be a good fit in their college To make that this college will be a good fit for you The prompt may be phrased in one of two ways, “why us?” or “why you?”, but these are sides of the same coin and will be addressed in english language, your essay regardless of the india prompt style. Writing the perfect “why this school” essay first requires researching the specific things that appeal to you about this school. You can find this information by: Visiting campuses in person or virtually to interact with current students and faculty Asking questions from your college interviewer or from reps at college fairs The college’s own materials like their brochures and compare texting essay website, their alumni magazine, campus newspaper, or their social media Other sites on the internet To find a topic to write about, find the three to five things that really speak to education india, you about the school and then link each of them yourself, your interests, your goals, and your strengths. Avoid writing about cliches that could be true for any school, like architecture, geography, weather, or sports fandom. Instead, focus on the details that differentiate your target school from all the history essay others. Are you also working on your personal statement?
If you're using the Common App, check out completely breakdown of the Common App prompts and our guide to picking the best prompt for you. If you're applying to the University of California, we've got an value education india in-depth article on practice how to education essay, best write the UC personal statements. And if you're submitting ApplyTexas applications, read our helpful explainer on how to approach the and effect of domestic violence essay many different ApplyTexas essay prompts. In the middle of the rest of the college application process? We can also help you ask for recommendations , show you how to write about value education essay extracurriculars , and illegal immigration outline for research give advice on how to research colleges . Want to improve your SAT score by 160 points or your ACT score by 4 points?
We've written a guide for each test about the value essay top 5 strategies you must be using to essay prompt, have a shot at improving your score. Download it for free now: Have friends who also need help with test prep? Share this article! Anna scored in value education essay india, the 99th percentile on her SATs in high school, and illegal for research paper went on to major in English at Princeton and to get her doctorate in English Literature at education essay india Columbia. She is passionate about improving student access to higher education.
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