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Multicast Routing In Ad Hoc wireless networks. By Liu Kebin. Outline. Introduction Issues Classifications Tree-Based Protocols BEMRP [1] MZRP [2] MCEDAR [4] References. Introduction. Multicast routing Communication among a given set of nodes Better than multiple unicast
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Multicast RoutingIn Ad Hoc wireless networks By Liu Kebin
Outline • Introduction • Issues • Classifications • Tree-Based Protocols • BEMRP [1] • MZRP [2] • MCEDAR [4] • References
Introduction • Multicast routing • Communication among a given set of nodes • Better than multiple unicast • Multicast routing in wired network • DVMRP, MOSPF, CBT, PIM • Establish a routing tree for a multicast session • Packets are sent to all nodes in the tree • Not appropriate for ad hoc, why?
Constraints in Ad Hoc • Dynamically changing topology • Low bandwidth • Less reliable links
Issues • Challenges • Limited bandwidth • Error-prone shared broadcast channel • Mobility of nodes • Limited energy • Hidden terminal problem • Limited security • Targets • Robustness • Efficiency • QoS
Tree-Based Protocols • Source-Tree-Based • Multicast tree is maintained per source • BEMRP • MZRP • MCEDAR • Shared-Tree-Based • Multicast tree is shared by all sources in the multicast group
Bandwidth-efficient multicastrouting protocol (BEMRP) • Abstract • Three phases • Choose the nearest forwarding nodes in the tree • Prune useless nodes in tree • Bandwidth efficient
Tree Maintenance Phase • Broadcast-multicast scheme • Upstream node floods broadcast-multicast packet • Isolated node receives this packet and rejoin the group • Local rejoin scheme • Isolated node floods Join control packet • Upstream nodes send back reply packet • Isolated node receives this reply and rejoin the group
Rout Optimization phase • Prune unwanted tree nodes • By Quit message
Advantages and Disadvantages • Advantages • Bandwidth efficient • Disadvantages • Long distance between source and receiver • High probability of path breaks • High delay
Multicast Zone Routing Protocol(MZRP) • Abstract • Each node is associated with a routing zone • Attempt to combine on-demand and table-driven routing • Two phases
Tree Initialization Phase • Create a multicast delivery tree • Two-stage process • Multicast tree creation inside a zone • Tree-Create message • Tree-Create-ACK message • Multicast tree extension • Tree-Propagate
Tree Maintenance Phase • Source node send the Tree-Refresh packet periodically • If tree node does not receive this packet for a special period, it is isolated • Downstream nodes are responsible for rejoining the group (similar to local rejoin scheme) • Join packet • JoinAck packet
Advantages and Disadvantages • Advantages • Reduce control overhead because it runs over Zone routing protocol • Disadvantages • Long wait for the far node because of the Tree-Propagate message
Multicast Core-Extraction DistributedAd Hoc Routing (MCEDAR) • Abstract • Use the underlying infrastructure “mgraph” fro forwarding packets • Form the minimum dominating set (MDS) with “core nodes” • Node who wants to join a group sends a JoinReq packet • Node join the group by receiving JoinAck packet • While isolated, node issues a JoinReq again
Advantages and Disadvantages • Advantages • Robust • As efficient as other Tree-Based protocols • Disadvantages • Complex • Increasing control overhead
References • [1] T.Ozaki, J.B.Kin, and T.Suda, “Bandwidth-Efficient Multicast Routing Protocol for Ad Hoc Networks” • [2] V.Devarapalli, A.A.Selcuk, etc, “MZR: A Multicast Protocol for Mobile Ad Hoc Networks” • [3] Z.J.Haas, M.R.Pearlman, and P.Samar, “Zone Rounting Protocol (ZRP)” • [4] P. Sinha, R.Sivakumar, and V.Bharghavan, “MCEDAR: Multicast Core Extraction Distributed Ad Hoc Routing”