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Routing Protocols

Routing Protocols. A Review of Current Routing Protocols for Ad Hoc Mobile Wireless Networks. Introduction. Mobile Wireless Networks Infrastructured Fixed and Wired Gateways Connecting to the nearest Base Station Ad hoc No Fixed Routers Moving Nodes Dynamic Connections Routing Protocols

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Routing Protocols

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  1. Routing Protocols

  2. A Review of Current Routing Protocols for Ad Hoc Mobile Wireless Networks

  3. Introduction Mobile Wireless Networks Infrastructured Fixed and Wired Gateways Connecting to the nearest Base Station Ad hoc No Fixed Routers Moving Nodes Dynamic Connections Routing Protocols Correct and Efficient Route Establishment between Nodes Goal Minimum Overhead and Bandwidth Consumption

  4. Classification Existing Ad Hoc Routing Protocols Table-Driven Routing (Proactive) Tables to Store Routing Information e.g. Next hop toward destination Source-Initiated On-Demand Routing (Reactive) Route Creation by the Source Only when Desired Source saves the Whole Route to Destination

  5. Classification Proactive Reactive

  6. Classification Proactive Reactive

  7. Destination-Sequenced Distance-Vector Routing(DSDV) Based on Bellman-Ford Routing Mechanism Loop-Free (Be patient!) Routing Tables (Destination, # of Hops, Seq. No.) Periodic Updates Full Dump: all available routing information Incremental Updates: Changes since the last full dump Drawback Periodic Updates regardless of # of Network Topology Changes

  8. Distance Vector (Broken Link) 1 1 1 D A B C

  9. Distance Vector (Loops) (D, 2) (D, 2) 1 1 1 D A B C

  10. Distance Vector (Count to Infinity) (D,5) (D,4) (D,4) (D,3) (D,2) (D,2) 1 1 1 D A B C

  11. DSDV (no loops, no count to infinity) 2. B does its broadcast-> no affect on C (C knows that B has stale information because C has higher seq. number for destination D)-> no loop -> no count to infinity 1. Node C detects broken Link:-> Increase Seq. Nr. by 1 (D, 2, D-100) (D, 2, D-100) D A B C

  12. Clusterhead Gateway Switch Routing(CGSR) Proactive Reactive

  13. Clusterhead Gateway Switch Routing(CGSR) Based on DSDV but Hierarchical Addressing First Nodes are Clustered Cluster Heads (cluster representative) Dynamic Head election Forward on behalf of Source nodes Gateways Nodes in communication range of at least two cluster heads Ordinary Nodes Cluster-Head-to-Gateway Routing S.Node > S.Cluesterhead > Gateway > D.Clusterhead > D.Node Tables, broadcast using the DSDV Cluster Member (D.Node > Clusterhead) Routing Table (Clusterhead > Next Hop)

  14. Clusterhead Gateway Switch Routing(CGSR)

  15. Wireless Routing Protocol(WRP) Proactive Reactive

  16. Wireless Routing Protocol(WRP) Each node maintains 4 Tables Distance Table: saves distance to destinations Routing Table: saves next hop Link-cost Table: saves cost of relaying info in each neighbor Message Retransmission List Table: saves retransmission-related entries such as retransmission counter… Keep track of alive neighbors Acknowledgements and other messages Periodic *hello* messages Drawback Maintaining 4 tables requires large amount of memory Periodic *hello* messages consume resources

  17. Ad hoc On-Demand Distance Vector Routing(AODV) Proactive Reactive

  18. Ad hoc On-Demand Distance Vector Routing(AODV) On-demand version of the DSDV  Minimize the Required Broadcasts How to send a message? Initiate Path Discovery Process Broadcasts Route Request (RREQ) to neighbors Until either Destination or an Intermediate Node with Route is found Nodes Records the Node who sends the First Copy of RREQ Establish the Reverse Path! Only Supports the Symmetric Links  (why?) Route Table Timer Removes stale routes! Maintenance Link Failure Notification Message

  19. AODV (Example) A L Y F J B K D Destination P G Source S C E H I T Z RREQ

  20. AODV (Example) A L Y F J B K D Destination P G S C Source E H I T Z Reverse Path Setup

  21. AODV (Example) A L Y F J B K D Destination P G Source S C E H I T Z

  22. AODV (Example) A L Y F J B K D Destination P G Source S C E H I T Z

  23. AODV (Example) A L Y F J B K D Destination P G Source S C E H I T Z RREP

  24. AODV (Example) A L Y F J B K D Destination P G Source S C E H I T Z Forward Path Setup

  25. AODV (Example) A L Y F J B K D Destination P G Source S C E H I T Z

  26. AODV (Example) A L Y F J B K D Destination P G Source S C E H I T Z

  27. AODV (Example) A L Y F J B K D Destination P G Source S C E H I T Z

  28. Dynamic Source Routing(DSR) Proactive Reactive

  29. Dynamic Source Routing(DSR) Each node has a Source Route Cache Route Discovery Broadcast Route Request (source addr, dest addr, ID) Receiving node Checks its own Route Cache If nothing found: adds its own addr to packet, and broadcasts If found: does Route Replying (Coming soon…) In asymmetric links case, other routes are used to reply Route Maintenance Route error packets Nodes remove routes containing faulty node!

  30. Forward “route request” packet (RREQ) 〈initiator address, request id〉 Append it’s own address to the route record Send “route reply” packet (RREP) (route cache or reverse request ) Send “route reply” packet (RREP) (route cache or reverse request ) Send “route request” packet (RREQ) 〈initiator address, request id〉 Data packet (A, B, C, E, F) Route cache of node A Route cache of node A Route cache of node A B: A, B F: A, B, C, E, F B: A, B F: A, B, C, E, F B: A, B Route Discovery Node A sends node F a message No route to node F D destination B F source C A E

  31. Temporally Ordered Routing Algorithm(TORA) Proactive Reactive

  32. What is that?!? Temporally Ordered Routing Algorithm(TORA) Based on *Link-Reversal* Algorithm

  33. Link-Reversal Algorithm Each node has two types of links Upstream (incoming) Downstream (outgoing) When a node has no downstream links, It Reverses the Direction of One or More Links Links are Directed Based on *Height* Metric! Links are directed from the Higher node to the Lower node

  34. Temporally Ordered Routing Algorithm(TORA) Key Idea! Localization of Control Messages to Nodes NEAR the Changing part *Height* Concept Establish a Directed Acyclic Graph (DAG)

  35. Height Concept in Link-Reversal

  36. Height Concept in Link-Reversal

  37. Height Concept in Link-Reversal

  38. Height Concept in Link-Reversal

  39. Height Concept in Link-Reversal

  40. Height Concept in Link-Reversal

  41. Associativity-Based Routing(ABR) Proactive Reactive

  42. Associativity-Based Routing(ABR) New metric: *Degree of Association Stability (DAS)* Nodes generate periodic Beacons to Announce Existence Receiving node increments the DAS tick w.r.t sending node High DAS shows low mobility  Low DAS shows high mobility  Route Discovery Source node sends Broadcast Query (BQ) Receiving Nodes Append their addrs, and associativity ticks to packets Destination Selects Best Receiving Route and sends back Reply

  43. Associativity-Based Routing(ABR)

  44. Signal Stability Routing(SSR) Proactive Reactive

  45. Signal Stability Routing(SSR) Route selection based on Signal Strength Routes with Stronger Connectivity are Chosen! Periodic Beacons Records the signal strength of neighboring nodes Strong or Weak Route Search Process First, only Requests from Strong Channels are processed If not possible, Weak Channels are also acceptable! Path Failure Error message back to the source Source initiates a new route search process

  46. Ad hoc Networks Routing Algorithms

  47. Table-Driven vs. On-Demand

  48. Conclusions! Thanks for Attention!  Any Questions?  Next Papers…

  49. Directed Diffusion: A Scalable and Robust Communication Paradigm for Sensor Networks

  50. Disaster Response Circulatory Net Distributed sensor networks • Sensor nodes • Capable of sensing, communication, and even computation • Distributed micro-sensing of environmental phenomena • Inhospitable physical environments , e.g. remote geographic regions or toxic urban locations, disasters, … • Low maintenance sensing in low accessible environments, e.g. large industrial plants, aircraft interiors , human body, … • How it works? • Posing question by human operator to some nodes • Specific nodes get tasked to collect info • Collaborate to disambiguate data • One of nodes reports the result

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