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Overlay Multicast for MANETs Using Dynamic Virtual Mesh

Chao Gui, Prasant MohapatraComputer Science department of University of California

Wireless Networks 2007

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Outline

Introduction Motivations PAST-DM protocol Performance Evaluation Conclusions

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Introduction

Multicasting in MANET face many challenges Continuous changes in network topology Limited channel bandwidth

Multicast routing protocol can classify into Tree-based Mesh-based Combined method

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Introduction- Overlay multicast in MANETs

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Motivations Traditional MANET multicast protocols

Maintain state information at all network node Member node and Non-Member Node

Widespread maintenance of state information lowers the protocol robustness against the node mobility Fast moving

The Group-Join and Group-Leave is a burden to both member nodes and participating non-member nodes

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Motivations- Goal

Minimized the control overhead Maintain a partial view of virtual mesh

Balanced between low control overhead and high multicast tree quality

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PAST-DM

Two parts Dynamic Mesh (DM)

Group_REQ flooding Dynamic mesh maintenance by link state excha

nge Detection of remote island

Progressively Adapted Sub-Tree forwarding Progressively adapted source-based tree Join and Leave

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DM

C

AB

D

Virtual topology Physical topology

C

AB

D

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34

5

source source

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DM

C

AB

D

CA

BD

C

AB

D12

3

4

5

3

C

AB

D12

3

4

5

B-5 and 5-C redundant

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DM- Group_REQ flooding

Group_REQ packet Only rebroadcast by non-member nodes, no

t by member node The packet will be consumed by surroundin

g members

Mainland Island

Group_REQ……

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DM- Group_REQ flooding

Rn

Rl

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DM- Group_REQ flooding

VN set definition

Set PLST_TTL(nodei)

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DM- Dynamic mesh maintenance by link state exchange

Each node records its virtual neighbors (VN) as its virtual link state The maximum degree of the virtual topology is contr

olled Link State Table (LST)

At each member node, the topology map represented as a LST

Maintain the link state information of all group nodes obtained from VNs

Periodically exchanges LST with its neighbors A TTL bounded local flooding

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DM- Dynamic mesh maintenance by link state exchange

A- B,EB- A,C,DE- A,D

B- A,C,DA- B,EC- B,DD- B,C,E

E- A,DA- B,ED- B,C,E

D- B,C,EB- A,C,DC- B,DE- A,D

C- B,C,EB- A,C,DD- B,C,E

A

B C

DE

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DM- Dynamic mesh maintenance by link state exchange

A- B,EB- A,C,DE- A,DC- B,DD- B,C,E

B- A,C,DA- B,EC- B,DD- B,C,EE- A,D

E- A,DA- B,ED- B,C,EB- A,C,DC- B,D

D- B,C,EB- A,C,DC- B,DE- A,DA- B,E

C- B,C,EB- A,C,DD- B,C,EE- A,DA- B,E

A

B C

DE

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DM- Dynamic mesh maintenance by link state exchange

Link State Table Far_LST

Maintain long unicast tunnel in a virtual mesh Near_LST

Each member node locally flood within a limited region (TTL)

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DM- Detect of remote island

Use “Leaky Bucket” The initial level of the LB at each node is

determined by its link state Each LB leaks at constant rate When node I stays in the mainland, it

constantly receives LST packet, which maintain its LB level

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DM- Detect of remote island

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PAST- Progressively adapted source-based algorithm

Link state entries Less accurate with increasing hop distance

ds(n) denote the hop distance from source node s to node n Virtual link (n1 , n2)

ds(n1 , n2)=min [ ds(n1) , ds(n2) ] c(n1 , n2) be the cost of virtual link (n1, n2)

ac(n1, n2)=ds(n1, n2)‧c(n1, n2)

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Performance Evaluation Mobile Node : 100 Range : 2000m × 750m Communication Range : 250m Moving Model

Each node select a destination location randomly Moving straight toward to destination with constant

speed Moving speed is uniform distributed over [10,20]

Group Size : 5,10,20,30,40 Simulator : GloMoSim & Developed simulator

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Conclusions

PAST-DM Dynamic virtual mesh that adapts itself

to the mobility of network nodes Novel tree construction algorithm

Fully utilizes the latest loco topology information

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Thank You