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

1

CSE 6007 Mobile Ad Hoc Wireless Networks

Outline

2

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

3

4

1

2

6

7

9

3

4

5

8

10

The main routing problems for MANETs

Node mobility

Routing path broken frequently

6

7

8

9

10

11

12

13

14

15

16

Traditional ad-hoc routing protocols

18

19

20

21

22

15

14

13

1211

10 98

7

6

5

4

3

21

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:

15

14

13

1211

10

98

7

6

5

4

3

21

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.)

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

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

43

Route Discovery in DSR

B

A

S E

F

H

J

D

C

G

IK

Represents transmission of RREQ

Z

YBroadcast

M

N

L

[S]

[X,Y] Represents route record stored in RREQ

44

Route Discovery in DSR

B

A

S E

F

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]

45

Route Discovery in DSR

B

A

S E

F

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

Z

Y

M

N

L

[S,C,G]

[S,E,F][S,B,A]

[S,B,H]

46

Route Discovery in DSR

B

A

S E

F

H

J

D

C

G

IK

Z

Y

M

J and K both broadcast RREQ to D Their transmissions may collide at D

N

L

[S,C,G,K]

[S,E,F,J]

[S,B,H,I]

47

Route Discovery in DSR

B

A

S E

F

H

J

D

C

G

IK

Z

Y

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

M

N

L

[S,E,F,J,M]

48

Route Reply in DSR

B

A

S E

F

H

J

D

C

G

IK

Z

Y

M

N

L

RREP [S,E,F,J,D]

Represents RREP control message

49

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

B

A

S E

F

H

J

D

C

G

IK

Z

Y

M

N

L

RERR [J-D]

Route Error Packet : RERR

50

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

B

A

S E

F

H

J

D

C

G

IK

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

51

Use of Route Caching Can Reduce Propagation of Route Requests

Route Replies (RREP) from node K and D limit flooding of RREQ.

B

A

S E

F

H

J

D

C

G

IK

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]

52

53

54

55

56

57

Route Requests in AODV

B

A

E

F

H

JC

G

IK

Z

Y

Represents a node that has received RREQ for D from S

M

N

L

D

S

58

Route Requests in AODV

B

A

E

F

H

JC

G

IK

Represents transmission of RREQ

Z

YBroadcast transmission

M

N

L

S

D

59

Route Requests in AODV

B

A

E

F

H

JC

G

IK

Represents links on Reverse Path

Z

Y

M

N

L

S

D

60

Reverse Path Setup in AODV

B

A

E

F

H

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

Z

Y

M

N

L

S

D

61

Reverse Path Setup in AODV

B

A

E

F

H

JC

G

IK

Z

Y

M

N

L

S

D

62

Reverse Path Setup in AODV

B

A

E

F

H

JC

G

IK

Z

Y

• Node D does not forward RREQ, because node D is the intended target of the RREQ

M

N

L

S

D

63

Forward Path Setup in AODV

B

A

E

F

H

JC

G

IK

Z

Y

M

N

L

Forward links are setup when RREP travels alongthe reverse path

Represents a link on the forward path

S

D

64

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.

1 23

S D

RERR RERR3´

65

66

67

68

69

70

71

72

73

74

75

76

77

78

79

80

81

82

83

84

85

86

87

88