Unit II Topic 8-15 Routing Protocols for Ad Hoc Wireless Networks Department of Computer Science and...
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Unit II Topic 8-15 Routing Protocols for Ad Hoc Wireless Networks Department of Computer Science and Engineering Kalasalingam University 1 CSE 6007 Mobile Ad Hoc Wireless Networks
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Transcript of Unit II Topic 8-15 Routing Protocols for Ad Hoc Wireless Networks Department of Computer Science and...
Unit II Topic 8-15 Routing Protocols for Ad Hoc Wireless Networks
Department of Computer Science and EngineeringKalasalingam University
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CSE 6007 Mobile Ad Hoc Wireless Networks
Outline
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IntroductionTopic 8 : Issues in Designing A Routing Protocol for Ad
Hoc Wireless NetworksTopic 9 : Classification of Routing ProtocolsTopic 10 : Table Driven Routing Protocols Topic 11 : On-Demand Routing ProtocolsTopic 12 : Hybrid Routing Protocols Topic 13 : Routing Protocols with Efficient Flooding
MechnismsTopic 14 : Hierarchical Routing ProtocolTopic 15 : Power Aware Routing Protocol
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The main routing problems for MANETs
Node mobility
Routing path broken frequently
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Traditional ad-hoc routing protocols
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1211
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Dest NextNode Dist seqNo2 2 1 223 2 2 264 5 2 325 5 1 1346 6 1 1447 2 3 1628 5 3 1709 2 4 186
10 6 2 14211 6 3 17612 5 3 19013 5 4 19814 6 3 21415 5 4 256
Routing table for Node 1
Table-driven routing protocol – DSDV (cont.)
Example:
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1211
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Routing table for Node 1
Dest NextNode Dist seqNo2 2 1 223 2 2 264 5 2 325 5 1 1346 6 1 1447 2 3 1628 5 3 1709 2 4 186
10 6 2 14211 5 4 18012 5 3 19013 5 4 19814 6 3 21415 5 4 256
Table-driven routing protocol – DSDV (cont.)
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Route Discovery in DSR
B
A
S E
F
H
J
D
C
G
IK
Z
Y
Represents a node that has received RREQ for D from S
M
N
L
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Route Discovery in DSR
B
A
S E
F
H
J
D
C
G
IK
Represents transmission of RREQ
Z
YBroadcast
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N
L
[S]
[X,Y] Represents route record stored in RREQ
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Route Discovery in DSR
B
A
S E
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H
J
D
C
G
IK
• Node H receives packet RREQ from two neighbors: potential for collision
Z
Y
M
N
L
[S,E]
[S,C]
[S,B]
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Route Discovery in DSR
B
A
S E
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H
J
D
C
G
IK
• C receives RREQ from G and H, but does not forward
it again, because C has already forwarded RREQ once
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Y
M
N
L
[S,C,G]
[S,E,F][S,B,A]
[S,B,H]
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Route Discovery in DSR
B
A
S E
F
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J
D
C
G
IK
Z
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J and K both broadcast RREQ to D Their transmissions may collide at D
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[S,C,G,K]
[S,E,F,J]
[S,B,H,I]
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Route Discovery in DSR
B
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S E
F
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J
D
C
G
IK
Z
Y
D does not forward RREQ, because D is the intended target
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[S,E,F,J,M]
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Route Reply in DSR
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S E
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J
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IK
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Y
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RREP [S,E,F,J,D]
Represents RREP control message
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An Example of Route Maintenance
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
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S E
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J
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IK
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RERR [J-D]
Route Error Packet : RERR
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Use of Route Caching Can Speed up Route Discovery
When node Z sends a route request for node C, node K sends back a routereply [Z,K,G,C] to node Z using a locally cached route
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S E
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IK
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[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
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Use of Route Caching Can Reduce Propagation of Route Requests
Route Replies (RREP) from node K and D limit flooding of RREQ.
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S E
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J
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IK
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[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]
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Route Requests in AODV
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A
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JC
G
IK
Z
Y
Represents a node that has received RREQ for D from S
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D
S
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Route Requests in AODV
B
A
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F
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JC
G
IK
Represents transmission of RREQ
Z
YBroadcast transmission
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N
L
S
D
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Route Requests in AODV
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A
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F
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JC
G
IK
Represents links on Reverse Path
Z
Y
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N
L
S
D
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Reverse Path Setup in AODV
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JC
G
IK
• Node C receives RREQ from G and H, but does not forward it again, because node C has already forwarded RREQ once
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N
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S
D
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Reverse Path Setup in AODV
B
A
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JC
G
IK
Z
Y
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S
D
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Reverse Path Setup in AODV
B
A
E
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JC
G
IK
Z
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• Node D does not forward RREQ, because node D is the intended target of the RREQ
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N
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S
D
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Forward Path Setup in AODV
B
A
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JC
G
IK
Z
Y
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Forward links are setup when RREP travels alongthe reverse path
Represents a link on the forward path
S
D
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Route Maintenance
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.
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S D
RERR RERR3´
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