Dynamic source routing


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Dynamic source routing

  1. 1. DSR: The Dynamic Source RoutingProtocol for Multi-Hop Wireless Ad HocNetworks Presenter Ashraf Uddin Sujit Singh South Asian University (Master of Computer Applications) http://ashrafsau.blogspot.in/ http://ashrafsau.blogspot.in/
  2. 2. Routing Overview Network with nodes, edges Goal: Devise scheme for transferring message from one msg node to another  Destination routing  Source routing http://ashrafsau.blogspot.in/
  3. 3. Source (“path”) routing Source specifies entire route: places complete path to destination in message header: A – D – F – G Intermediate nodes just forward to specified next hop: D would look at path in header, forward to F Like airline travel – get complete set of tickets to final destination before departing… http://ashrafsau.blogspot.in/
  4. 4. Destination (“hop-by-hop”) routing Source specifies only destination in message header: G Intermediate nodes look at destination in header, consult internal tables to determine appropriate next hop Like postal service – specify only the final destination on an envelope, and intermediate post offices select where to forward next… http://ashrafsau.blogspot.in/
  5. 5. Ad Hoc Routing Every node participates in routing: no distinction between “routers” and “end nodes” No external network setup: “self-configuring” Especially useful when network topology is dynamic (frequent network changes – links break, nodes come and go) http://ashrafsau.blogspot.in/
  6. 6. Common application Mobile wireless hosts  Only subset within range at given time  Want to communicate with any other node http://ashrafsau.blogspot.in/
  7. 7. DSR Protocol Activities Route discovery  Undertaken when source needs a route to a destination Route maintenance  Used when link breaks, rendering specified path unusable http://ashrafsau.blogspot.in/
  8. 8. Route Discovery• The source sends a broadcast packet which contains source address, destination address, request id and path.• If a host saw the packet before, discards it.• Otherwise, the route looks up its route caches to look for a route to destination, If not find, appends its address into the packet, rebroadcast,• If finds a route in its route cache, sends a route reply packet, which is sent to the source by route cache or the route discovery. http://ashrafsau.blogspot.in/
  9. 9. source broadcasts a packet containing address of source anddestination source (1,4) 1 4 The destination sends a reply packet to source. 8 (1,3) destination 3 7 (1,4,7) 2 The node discards the packets having been seen (1,2) 6 5 (1,3,5) (1,3,5,6) The route looks up its route caches to look for a route to destination If not find, appends its address into the packet http://ashrafsau.blogspot.in/
  10. 10. How to send a reply packet If the destination has a route to the source in its route cache, use it Else if symmetric links are supported, use the reverse of route record Else if symmetric links are not supported, the destination initiates route discovery to source http://ashrafsau.blogspot.in/
  11. 11. Route Maintenance Whenever a node transmits a data packet, a route reply, or a route error, it must verify that the next hop correctly receives the packet. If not, the node must send a route error to the node responsible for generating this route header  Intermediate nodes “eavesdrop”, adjust cached routes Source deletes route; tries another if one cached, or The source restart the route discovery http://ashrafsau.blogspot.in/
  12. 12. Route Maintenance……A B C D E Route error message: C-D is broken http://ashrafsau.blogspot.in/
  13. 13. 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 http://ashrafsau.blogspot.in/
  14. 14. Additional Route Discovery features DSR route discovery does not allow nodes like F to reply to RREQ http://ashrafsau.blogspot.in/
  15. 15. Additional Route Discovery features http://ashrafsau.blogspot.in/
  16. 16. Additional Route Discovery features http://ashrafsau.blogspot.in/
  17. 17. Additional Route Discovery features Node C may infer Preventing Route Reply that the initiator has already received a h=2 storms Route Reply giving  Many Route Reply message C a better route could be send to A from the because the data A’s neighbors packet received  To avoid a possible local from B contains a congestion, each nodes must value of “h” less wait a variable period before than its h’s value A B G sending the reply.  Delay period d = H(h - 1 + r) h=1  Each node network interfaces works into “promiscuous” E receive mode. h=3 http://ashrafsau.blogspot.in/
  18. 18. Additional Route Discovery features Route request Hop limits  “Nonpropagating” Route Request(hop lim 0)  To determine if the target is 2 Hop limit neighbour or a neighbour has a route 1 Hop limit to the target cached.  “Propagating” Route Request( no hop lim) Non Propagating  If no route reply is recived after a Route Request The expanding ring search approach can carry to the short timeout. average latency increasing  “Expanding ring”  Increase hop value stepwise if no route reply is recieved. http://ashrafsau.blogspot.in/
  19. 19. Additional Route Maintenance features http://ashrafsau.blogspot.in/
  20. 20. Additional Route Maintenance features http://ashrafsau.blogspot.in/
  21. 21. Additional Route Maintenance features http://ashrafsau.blogspot.in/
  22. 22. Additional Route Maintenance features http://ashrafsau.blogspot.in/
  23. 23. Support for Heterogeneous networks & mobile IP Heteregenous network : Different kind of devices with different interfaces. Possibly , multiple interfaces( short range & long range) http://ashrafsau.blogspot.in/
  24. 24. DSR evaluation Simulation  To analyse the behavior and performance of DSR.  To Compare with other routing protocols Set Up:  Ad hoc of 50 mobiles nodes  15 minutes ( 900 seconds) simulation time.  CBR data traffic  20 mobile nodes traffic sources; 4 packets/sec.  Random waypoint mobility model ( pause time) http://ashrafsau.blogspot.in/
  25. 25. Packet Delivery Ratio(with movement speed 1m/s) http://ashrafsau.blogspot.in/
  26. 26. Routing Overhead(with movement speed 1m/s) http://ashrafsau.blogspot.in/
  27. 27. Packet Delivery Ratio(with movement speed 20m/s) http://ashrafsau.blogspot.in/
  28. 28. Routing Overhead(with movement speed 20m/s) http://ashrafsau.blogspot.in/
  29. 29. RESULT At both movement speeds, DSR delivers almost all data packets, regardless of pause time. 100% delivery ratio at pause time 900 sec, a stationary network. At 1 m/s delivery ratio> 99.5% At 20 m/s delivery ratio> 98% http://ashrafsau.blogspot.in/
  30. 30. Advantages Routes maintain only between nodes who need to communicate. Reduces overhead of routing maintenance. route caching reduces route discovery overhead. A single route may yield many routes to the destination. http://ashrafsau.blogspot.in/
  31. 31. Disadvantages Packet header size grows with route length due to source routing. Flood route request may potentially reach all nodes in the network. Route reply storm problem. http://ashrafsau.blogspot.in/
  32. 32. Conclusion Excellent performance for routing in multi-hop ad hoc. Very low routing overhead. Able to deliver almost all originated data packets, even with rapid motion of all nodes. http://ashrafsau.blogspot.in/
  33. 33. THANKShttp://ashrafsau.blogspot.in/
  34. 34. Reference[1]. David B. Johnson, David A. Maltz, and Josh Broch, "DSR: The Dynamic Source Routing Protocol for Multi-Hop Wireless Ad Hoc Networks", in Ad Hoc Networking, edited by Charles E. Perkins, Chapter 5, pp. 139-172, Addison- Wesley, 2001. Invited paper. http://ashrafsau.blogspot.in/
  35. 35. ?????? QUESTION??????http://ashrafsau.blogspot.in/