220 likes | 323 Views
Overlay Multicast for MANETs Using Dynamic Virtual Mesh. Chao Gui, Prasant Mohapatra Computer Science department of University of California Wireless Networks 2007. Outline. Introduction Motivations PAST-DM protocol Performance Evaluation Conclusions. Introduction.
E N D
Overlay Multicast for MANETs Using Dynamic Virtual Mesh Chao Gui, Prasant Mohapatra Computer Science department of University of California Wireless Networks 2007
Outline • Introduction • Motivations • PAST-DM protocol • Performance Evaluation • Conclusions
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
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
Motivations- Goal • Minimized the control overhead • Maintain a partial view of virtual mesh • Balanced between low control overhead and high multicast tree quality
PAST-DM • Two parts • Dynamic Mesh (DM) • Group_REQ flooding • Dynamic mesh maintenance by link state exchange • Detection of remote island • Progressively Adapted Sub-Tree forwarding • Progressively adapted source-based tree • Join and Leave
DM Virtual topology Physical topology D D 4 3 A A 1 2 source source B B C 5 C
DM D A A D C B B C B-5 and 5-C redundant 3 3 3 A A 4 1 2 4 1 B 2 B D D 5 C 5 C
DM- Group_REQ flooding • Group_REQ packet • Only rebroadcast by non-member nodes, not by member node • The packet will be consumed by surrounding members …… Group_REQ Island Mainland
DM- Group_REQ flooding Rn Rl
DM- Group_REQ flooding VN set definition Set PLST_TTL(nodei)
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 controlled • 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
DM- Dynamic mesh maintenance by link state exchange B- A,C,D A- B,E C- B,D D- B,C,E A- B,E B- A,C,D E- A,D B C C- B,C,E B- A,C,D D- B,C,E A E D E- A,D A- B,E D- B,C,E D- B,C,E B- A,C,D C- B,D E- A,D
DM- Dynamic mesh maintenance by link state exchange B- A,C,D A- B,E C- B,D D- B,C,E E- A,D A- B,E B- A,C,D E- A,D C- B,D D- B,C,E B C C- B,C,E B- A,C,D D- B,C,E E- A,D A- B,E A E D E- A,D A- B,E D- B,C,E B- A,C,D C- B,D D- B,C,E B- A,C,D C- B,D E- A,D A- B,E
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)
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
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)
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
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