1. CSE 6007 Mobile Ad Hoc Wireless Networks
Unit II Topic Routing Protocols for Ad Hoc Wireless Networks
Department of Computer Science and Engineering
Kalasalingam University

2. Outline
Introduction
Topic 8 : Issues in Designing A Routing Protocol for Ad Hoc
Wireless Networks
Topic 9 : Classification of Routing Protocols
Topic 10 : Table Driven Routing Protocols
Topic 11 : On-Demand Routing Protocols
Topic 12 : Hybrid Routing Protocols
Topic 13 : Routing Protocols with Efficient Flooding Mechnisms
Topic 14 : Hierarchical Routing Protocol
Topic 15 : Power Aware Routing Protocol

5. The main routing problems for MANETs8 10 9 7 4 6
Node mobility 
Routing path broken frequently 2 3 5 1

17. Traditional ad-hoc routing protocols

23. Table-driven routing protocol – DSDV (cont.)
Example:
Routing table for Node 1 15
Dest
NextNode
Dist
seqNo 2 1 22 3 26 4 5 32
134 6
144 7
162 8
170 9
186 10
142 11
176 12
190 13
198 14
214 15
256 14 13 11 12 10 9 8 6 4 7 5 3 1 2

24. Table-driven routing protocol – DSDV (cont.)
Routing table for Node 1 15
Dest
NextNode
Dist
seqNo 2 1 22 3 26 4 5 32
134 6
144 7
162 8
170 9
186 10
142 11
180 12
190 13
198 14
214 15
256 14 13 11 12 10 8 9 6 4 7 5 3 1 2

42. Route Discovery in DSR 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

43. Route Discovery in DSR Y Broadcast Z [S] S E F B C M L J A G H D K I N
Represents transmission of RREQ
[X,Y] Represents route record stored in RREQ

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

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

46. Route Discovery in DSR Y Z S E F [S,E,F,J] B C M L J A G H [S,B,H,I] DK I N
[S,C,G,K]
J and K both broadcast RREQ to D
Their transmissions may collide at D

47. 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
D does not forward RREQ, because D is the intended target

48. 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

49. An Example of Route MaintenanceB A S E F H J D C G I K Z Y M N L
RERR [J-D]
Route Error Packet : RERR
J sends a route error to S along route J-F-E-S when it finds link [J-D] broken
Nodes hearing RERR update their route cache to remove all invalid routes related with link J-D

50. Use of Route Caching Can Speed up Route DiscoveryB A S E F H J D C G I K Z M N L
[S,E,F,J,D]
[E,F,J,D]
[C,S]
[G,C,S]
[F,J,D],[F,E,S]
[J,F,E,S]
RREQ
[K,G,C,S]
RREP
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

51. Use of Route Caching Can Reduce Propagation of Route RequestsB A S E F H J D C G I K Z M N L
[S,E,F,J,D]
[E,F,J,D]
[C,S]
[G,C,S]
[F,J,D],[F,E,S]
[J,F,E,S]
RREQ
[K,G,C,S]
RREP
[D,K,G,,C]
Route Replies (RREP) from node K and D limit flooding of RREQ.

57. 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

58. Broadcast transmission
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

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

60. Reverse Path Setup in AODVY Z S E F B C M L J A G H D K I N
Node C receives RREQ from G and H, but does not forward
it again, because node C has already forwarded RREQ once

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

62. Reverse Path Setup in AODVY Z S E 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 RREQ

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

64. Route Maintenance 1 2 3 S D
RERR 3´
The link from node 3 to D is broken as 3 has moved away to a position 3´.
Node 2 sends a RERR message to 1 and 1 sends the message in turn to S.
S initiates a route discovery if it still needs the route to D.