260 likes | 435 Views
Multicast: Wired to Wireless. Hrishikesh Gossain Carlos de Morais Cordeiro Dharma P. Agrawal IEEE Communication Magazine June 2002 資工所 蔡家楷. Outline. Introduction Multicast Support Multicast in the Internet Multicast in Wireless Mobile Environment Conclusion & Future Direction.
E N D
Multicast: Wired to Wireless Hrishikesh Gossain Carlos de Morais Cordeiro Dharma P. Agrawal IEEE Communication Magazine June 2002 資工所 蔡家楷
Outline • Introduction • Multicast Support • Multicast in the Internet • Multicast in Wireless Mobile Environment • Conclusion & Future Direction
Introduction • Provide efficient way of services for application • Real-time Class、 Multiplayer on line gaming • IPv4 reserved Class D address to support multicasting
Multicast Support • Initial Support • Multicast-capable routers (MRouters) • Dedicated Tunnels • Multicast backbone (MBone) • Presently • No need dedicated tunnels • Native multicast
Multicast Support • Multicast Group Membership • IP supports dynamic joining and leaving of a group by IGMP (Internet Group Management Protocol)
Multicast Support • Packet Forwarding • Multicast forwarding algorithm • Source-based • Core-based
Source Router Membership Source-based • RPB – Reverse Path Broadcasting • Spanning tree is created for each (source,group) pair • TRPB – Truncated Reverse Path Broadcasting • Manage group by IGMP • Prune non-leaf router
Source-based • RPM – Reverse Path Multicasting • Spans only to routers and subnetwork with group member
Core-based • CBT - Core Based Tree • Build a single shred multicast tree with a core router • All packets are forwarded through the core • Group managed by the core • Receiver-oriented
Multicast in the Internet • Routing Protocol • DVMRP – Distance Vector Multicast Routing Protocol • Source-based • First packet forward to entire interface • Prune message • Graft message
Multicast in the Internet • Routing Protocol • MOSPF – Multicast Extensions to OSPF • Unicast routing information obtained from OSPF • Group membership obtained from IGMP • Build a multicast forwarding tree on demand for each (source,group) pair • Hierarchical routing – hosts are partitioned into autonomous system (ASs)
Multicast in the Internet • Routing Protocol • PIM-SM - Protocol-Interdependent Multicast-Sparse Mode • Support multicast independent of any underlying unicast routing protocol • For sparse distributed receiver on Internet
S M DR Group M RP S M DR M Multicast in the Internet • RP – Rendezvous point • Forwarding packets destined for the multicast group • DR – Designated router • Handles multicast group membership message in it’s domain
Multicast in Wireless Mobile Environment • Issue in Mobile Environment • Multicast forwarding algorithm • Dense or sparse mode protocols • QoS provisioning
Multicast in Wireless Mobile Environment • Proposals for multicast over MIP by IETF • Remote Subscription • An MH resubscribe to the multicast group each time it moves to a new foreign network • Frequent resubscription may lead to lost packets • Bidirectional Tunneling • Using unicast Mobile IP tunnels from their Has • Requires the HA of an MH to be a multicast router
Multicast in Wireless Mobile Environment • Multicast support using Mobile IP (MoM) • Tunnel convergence problem • Select one HA as DMSP (Designated Multicast Service Provider) • Packet loss when MH handoff • Select more than one DMSP
Multicast in Wireless Mobile Environment • Multicast for Mobility Protocols (MMP) • Provide fast and efficient handoffs for MH • Combines Mobile IP and CBT • MIP for controls communication up to the foreign network • CBT for movement of hosts inside foreign network
Multicast in Wireless Mobile Environment • MMP working flow • BS send beacon include multicast CoA • According CoA, MH send join message to BS • BS transmits a CBT join request to the Core • The core request the HA of MH to replace the CoA to its own address
Multicast in Wireless Mobile Environment • MMP drawback • Assumes a large-scale deployment of multicast-capable routers in each domain • Not protocol-indendpent
Reliable wireless Multicast Protocols • RMDP Protocol – Reliable Multicast Data Distribution Protocol • FEC (Forward error Control) & ARQ (Automatic Repeat Request) • A data object to be transmitted is a file • Split file into packets, and encoded to transmission • Drawback: encoding/decoding done by software, affect performance
Reliable wireless Multicast Protocols • RM2 Protocol – Reliable Mobile Multicast • Used for both wired & wireless • Rely on • IGMP: to manage group membership • IETF’s Mobile IP to support CoA • MADCAP – Multicast Address Dynamic Client Allocation Protocol
Reliable wireless Multicast Protocols • RM2 Protocol • NACK for request retransmitting • NACK: Negative acknowledgements • RS manage retransmission for fixed/mobile user or mixture of them
Conclusion & Future Direction • There is no one-size-fits-all protocol for multicast • Both wired & wireless multicast proposal designed to cope with specific scenario • QoS, Security and so on