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A Seminar On MANET (Mobile Ad-hoc Network). By: ANKUR KAUSHIK (MNW-883-2K11) RAHUL KUMAR ( MNW-893-2K11 ). Types of Wireless Networks. Infrastructure based(Cellular Network). Infrastructure less Network ( Mobile Ad hoc Network) (MANET )

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A Seminar On MANET (Mobile Ad-hoc Network)


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    1. A Seminar On MANET(Mobile Ad-hoc Network) By: ANKUR KAUSHIK (MNW-883-2K11) RAHUL KUMAR (MNW-893-2K11)

    2. Types of Wireless Networks • Infrastructure based(Cellular Network). • Infrastructure lessNetwork(Mobile Ad hoc Network) (MANET) (Ad hoc networks are defined as the category of wireless networks that utilize multi hop radio relaying and are capable of operating without the support of ant fix Infrastructure)

    3. Why Ad Hoc Networks ? • Ease of deployment • Speed of deployment • Decreased dependence on infrastructure

    4. Characteristics of an Ad-hoc network • Collection of mobile nodes forming a temporary network • Network topology changes frequently and unpredictably • No centralized administration or standard support services • Host is also function as router

    5. Applications • Personal area networking • cell phone, laptop, ear phone, wrist watch • Military environments • soldiers, tanks, planes • Civilian environments • taxi cab network • meeting rooms • sports stadiums • boats, small aircraft • Emergency operations • search-and-rescue • policing and fire fighting

    6. Many Variations • Fully Symmetric Environment • all nodes have identical capabilities andresponsibilities • Asymmetric Capabilities • transmission ranges and radios may differ • battery life at different nodes may differ • processing capacity may be different at different nodes • speed of movement • Asymmetric Responsibilities • only some nodes may route packets • some nodes may act as leaders of nearby nodes (e.g., cluster head)

    7. Issues In Ad Hoc Network • Medium access scheme • Routing • Transport Layer protocol • Pricing Scheme • Self Organization • Security • Energy Management • Addressing and service discovery • Scalability

    8. Medium access scheme • Hidden Terminal • Exposed Terminal • Throughput • Access delay • Fairness • Adaptive data rate control

    9. Routing • Mobility • Bandwidth • Error prone and shared channel • Location dependent contention • Quick route reconfiguration • Loop free routing • Minimum control overhead

    10. Multicasting • Efficiency • Efficient group management • Security

    11. Transport Layer protocols • Pricing Scheme • Self Organization

    12. Security • Denial Service • Resource Consumption • Energy Depletion • Buffer Flow • Host Impersonation • Information Disclosure • Interference

    13. Why is Routing Different in Ad Hoc ??? • Host mobility • Dynamic topology • link failure/repair due to mobility • Distributed Environment • Bandwidth constrained • Energy constrained

    14. Categorization of Ad-Hoc Routing Protocols

    15. Source Initiated On demand routing protocol • Reactive. • on-demand style: create routes only when it is desired by the source node • When a node requires a route to a destination, it initiates a route discovery process • Route is maintained until destination becomes unreachable, or source no longer is interested in destination.

    16. Table Driven Routing Protocol • Proactive. • Each node maintains one or more tables containing routing information to every other node in the network. • Tables need to be consistent and up-to-date view of the network. • Updates propagate through the network

    17. Table Driven Routing Protocol

    18. Destination-Sequenced Distance Vector Protocol (DSDV) • Basic Routing Protocol • Based on Bellman ford routing algorithm with some improvement • Each node maintains a list of all destinations and number of hops to each destination. • Each entry is marked with a sequence number. • Periodically send table to all neighbors to maintain topology • Two ways to update neighbors: • Full dump • Incremental update

    19. Example of DSDV A’s Routing Table Before Change A’s Routing Table After Change

    20. Advantages & Disadvantages of DSDV Advantages: • Less Delay to find route • Existing wired network protocol adaptable • Maintain up-to-date view of network Disadvantages: • Excessive control overhead. • Waiting time is Higher.

    21. Cluster-Head Gateway Switch Routing (CGSR) • Uses DSDV as an underlying protocol and Least Cluster Change (LCC) clustering algorithm • A clusterhead is able to control a group of ad-hoc hosts • Each node maintains 2 tables: -A cluster member table, containing the cluster head for each destination node -A DV-routing table, containing the next hop to the destination • The routing principle: • Lookup of the clusterhead of the destination node • Lookup of next hop • Packet send to destination • Destination cluster-head delivers packet

    22. Cluster-head Gateway Switch Routing (CGSR)

    23. Advantages & Disadvantages of(CGSR) Advantages: • Hierarchical scheme enables partial coordination • Better bandwidth utilization Disadvantages: • Too frequent cluster head selection can be an overhead and cluster nodes and Gateway can be a bottleneck • Increase the path length • Gateway conflicts

    24. Wireless Routing Protocol (WRP) • Predecessor to destination (next to last hop) in the shortest path used • Eliminates the “Count-to-infinity” problem and converges faster • Neighbor connectivity via periodic Hello messages • Update messages sent upon detecting a change in neighbor link

    25. Wireless Routing Protocol (WRP) • Each node i maintains a Distance table (iDjk), Routing table (Destination Identifier, Distance iDj ,Predecessor Pj ,the successor Sj), link cost table (Cost, Update Period) • Processing Updates and creating Route Table • Update from k causes ito re-compute the distances of all paths with k as the predecessor • For a destination j, a neighbor p is selected as the successor if p->j does not include i, and is the shortest path to j

    26. (10, I) (10, B) Operation (0, J) J 10 (2, K) B X 5 10 I 1 1 (2, K) 1 K (1, K) (11, B) (, K)

    27. Comparisons of the Characteristics of Table-Driven Routing Protocols

    28. Source Initiated On demand routing protocol

    29. Dynamic Source Routing (DSR) • When node S wants to send a packet to node D, but does not know a route to D, node S initiates a route discovery • Source node S floods Route Request (RREQ) • Each node appends own identifier when forwarding RREQ

    30. Route Discovery in DSR Y Z S [S,E] E F B C M L J A G [S,C] H D K I N • Node H receives packet RREQ from two neighbors: • potential for collision

    31. Route Discovery in DSR Y Z S E F [S,E,F] B C M L J A G H D K [S,C,G] I N • Node C receives RREQ from G and H, but does not forward it again, because node C has already forwarded RREQ once

    32. Route Discovery in DSR Y Z S E F [S,E,F,J] B C M L J A G H D K I N [S,C,G,K] • Nodes J and K both broadcast RREQ to node D • Since nodes J and K are hidden from each other, their • transmissions may collide

    33. Route Discovery in DSR Y Z S E [S,E,F,J,M] F B C M L J A G H D K I N • Node D does not forward RREQ, because node D • is the intended target of the route discovery

    34. Route Discovery in DSR • Destination D on receiving the first RREQ, sends a Route Reply (RREP) • RREP is sent on a route obtained by reversing the route appended to received RREQ • RREP includes the route from S to D on which RREQ was received by node D

    35. Route Reply in DSR Y Z S RREP [S,E,F,J,D] E F B C M L J A G H D K I N Represents RREP control message

    36. Route Reply in DSR • Route Reply can be sent by reversing the route in Route Request (RREQ) only if links are guaranteed to be bi-directional • To ensure this, RREQ should be forwarded only if it received on a link that is known to be bi-directional • If unidirectional (asymmetric) links are allowed, then RREP may need a route discovery for S from node D • Unless node D already knows a route to node S • If a route discovery is initiated by D for a route to S, then the Route Reply is piggybacked on the Route Request from D. • If IEEE 802.11 MAC is used to send data, then links have to be bi-directional (since Ack is used)

    37. Dynamic Source Routing (DSR) • Node S on receiving RREP, caches the route included in the RREP • When node S sends a data packet to D, the entire route is included in the packet header • hence the name source routing • Intermediate nodes use the source route included in a packet to determine to whom a packet should be forwarded

    38. Data Delivery in DSR Y Z DATA [S,E,F,J,D] S E F B C M L J A G H D K I N Packet header size grows with route length

    39. DSR Optimization: Route Caching • Each node caches a new route it learns by any means • When node S finds route [S,E,F,J,D] to node D, node S also learns route [S,E,F] to node F • When node K receives Route Request [S,C,G] destined for node, node K learns route [K,G,C,S] to node S • When node F forwards Route Reply RREP[S,E,F,J,D], node F learns route [F,J,D] to node D • When node E forwards Data [S,E,F,J,D] it learns route [E,F,J,D] to node D • A node may also learn a route when it overhears Data packets

    40. Use of Route Caching • When node S learns that a route to node D is broken, it uses another route from its local cache, if such a route to D exists in its cache. Otherwise, node S initiates route discovery by sending a route request • Node X on receiving a Route Request for some node D can send a Route Reply if node X knows a route to node D • Use of route cache • can speed up route discovery • can reduce propagation of route requests

    41. Use of Route Caching [S,E,F,J,D] [E,F,J,D] S E [F,J,D],[F,E,S] F B [J,F,E,S] C M L J A G [C,S] H D K [G,C,S] I N Z [P,Q,R] Represents cached route at a node (DSR maintains the cached routes in a tree format)

    42. Use of Route Caching:Can Speed up Route Discovery [S,E,F,J,D] [E,F,J,D] S E [F,J,D],[F,E,S] F B [J,F,E,S] C M L [G,C,S] J A G [C,S] H D K [K,G,C,S] I N RREP RREQ Z When node Z sends a route request for node C, node K sends back a route reply [Z,K,G,C] to node Z using a locally cached route

    43. Use of Route Caching:Can Reduce Propagation of Route Requests Y [S,E,F,J,D] [E,F,J,D] S E [F,J,D],[F,E,S] F B [J,F,E,S] C M L [G,C,S] J A G [C,S] H D K [K,G,C,S] I N RREP RREQ Z Assume that there is no link between D and Z. Route Reply (RREP) from node K limits flooding of RREQ. In general, the reduction may be less dramatic.

    44. Route Error (RERR) Y Z RERR [J-D] S E F B C M L J A G H D K I N J sends a route error to S along route J-F-E-S when its attempt to forward the data packet S (with route SEFJD) on J-D fails Nodes hearing RERR update their route cache to remove link J-D

    45. Route Caching: Beware! • Stale caches can adversely affect performance • With passage of time and host mobility, cached routes may become invalid • A sender host may try several stale routes (obtained from local cache, or replied from cache by other nodes), before finding a good route • An illustration of the adverse impact on TCP will be discussed later in the tutorial [Holland99]

    46. Ad Hoc On-Demand Distance Vector Routing (AODV) • DSR includes source routes in packet headers • Resulting large headers can sometimes degrade performance • particularly when data contents of a packet are small • AODV attempts to improve on DSR by maintaining routing tables at the nodes, so that data packets do not have to contain routes • AODV retains the desirable feature of DSR that routes are maintained only between nodes which need to communicate

    47. AODV • Route Requests (RREQ) are forwarded in a manner similar to DSR • When a node re-broadcasts a Route Request, it sets up a reverse path pointing towards the source • AODV assumes symmetric (bi-directional) links • When the intended destination receives a Route Request, it replies by sending a Route Reply • Route Reply travels along the reverse path set-up when Route Request is forwarded

    48. Route Requests in AODV Y Z S E F B C M L J A G H D K I N Represents a node that has received RREQ for D from S

    49. Route Requests in AODV Y Broadcast transmission Z S E F B C M L J A G H D K I N Represents transmission of RREQ