- AODV is a reactive routing protocol that establishes routes on-demand. When a node needs to send a packet to a destination, it broadcasts a route request (RREQ) to its neighbors. - Neighbors rebroadcast the RREQ, creating a reverse path back to the source. If the destination receives a RREQ, or an intermediate node knows of a route, it responds by unicasting a route reply (RREP) back to the source. - AODV sets up forward routes at intermediate nodes along the reverse path so bidirectional communication is possible. Route entries expire if not used recently and link failures are reported using route error (RERR) messages to update routing tables.

10. Medium Access Control in MANET

21. Routing Protocols

24. Distance Vector Routing: Example   2 

25. Link State Routing: Example

27. Mobile IP Router 1 Router 3 Router 2 S MH Home agent

28. Mobile IP Router 1 Router 3 Router 2 S MH Home agent Foreign agent move Packets are tunneled using IP in IP

29. Routing in MANET

33. Reactive Routing Protocols

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

36. Route Discovery in DSR B A S E F H J D C G I K Represents transmission of RREQ Z Y Broadcast transmission M N L [S] [X,Y] Represents list of identifiers appended to RREQ

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

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

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

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

55. Route Requests in AODV B A S E F H J D C G I K Represents links on Reverse Path Z Y M N L

57. Reverse Path Setup in AODV B A S E F H J D C G I K Z Y M N L

59. Forward Path Setup in AODV B A S E F H J D C G I K Z Y M N L Forward links are setup when RREP travels along the reverse path Represents a link on the forward path

65. Signal Stability Routing (SSA)

66. Signal Stability Routing (SSA)

67. Link Reversal Algorithm [Gafni81] A F B C E G D

68. Link Reversal Algorithm A F B C E G D Maintain a directed acyclic graph (DAG) for each destination, with the destination being the only sink This DAG is for destination node D Links are bi-directional But algorithm imposes logical directions on them

69. Link Reversal Algorithm Link (G,D) broke A F B C E G D Any node, other than the destination , that has no outgoing links reverses all its incoming links. Node G has no outgoing links

70. Link Reversal Algorithm A F B C E G D Now nodes E and F have no outgoing links Represents a link that was reversed recently

71. Link Reversal Algorithm A F B C E G D Now nodes B and G have no outgoing links Represents a link that was reversed recently

72. Link Reversal Algorithm A F B C E G D Now nodes A and F have no outgoing links Represents a link that was reversed recently

73. Link Reversal Algorithm A F B C E G D Now all nodes (other than destination D) have an outgoing link Represents a link that was reversed recently

74. Link Reversal Algorithm A F B C E G D DAG has been restored with only the destination as a sink

80. CGSR

81. CEDAR B A C E J S K D F H G A core node Node E is the dominator for nodes D, F and K

82. Proactive Routing Protocols

87. Hybrid Routing Protocols

89. Zone Routing Protocol (ZRP) Radius of routing zone = 2

91. Transport in MANET

97. Impact of Node Mobility TCP throughput degrades with increase in mobility but not always Larger route repair delays are especially harmful mobility causes link breakage, resulting in route failure TCP data and acks en route discarded TCP sender times out. Starts sending packets again Route is repaired No throughput No throughput despite route repair