Multicast: Wired to Wireless

Hrishikesh Gossain Carlos de Morais Cordeiro

Dharma P. AgrawalIEEE Communication Magazine

June 2002 資工所　蔡家楷

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Outline

Introduction Multicast Support Multicast in the Internet Multicast in Wireless Mobile

Environment Conclusion & Future Direction

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Introduction

Provide efficient way of services for application Real-time Class 、

Multiplayer on line gaming

IPv4 reserved Class D address to support multicasting

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Multicast Support

Initial Support Multicast-capable routers (MRouters) Dedicated Tunnels Multicast backbone (MBone)

Presently No need dedicated tunnels Native multicast

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Multicast Support

Multicast Group Membership IP supports dynamic joining and

leaving of a group by IGMP (Internet Group Management Protocol)

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Multicast Support

Packet Forwarding Multicast forwarding algorithm

Source-basedCore-based

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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

Membership

Router

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Source-based

RPM – Reverse Path Multicasting Spans only to routers and subnetwork

with group member

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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

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Multicast in the Internet

Routing Protocol DVMRP – Distance Vector Multicast

Routing ProtocolSource-basedFirst packet forward to entire interfacePrune messageGraft message

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Multicast in the Internet

Routing Protocol MOSPF – Multicast Extensions to OSPF

Unicast routing information obtained from OSPF

Group membership obtained from IGMPBuild a multicast forwarding tree on demand f

or each (source,group) pairHierarchical routing – hosts are partitioned int

o autonomous system (ASs)

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Multicast in the Internet

Routing Protocol PIM-SM - Protocol-Interdependent

Multicast-Sparse ModeSupport multicast independent of any

underlying unicast routing protocolFor sparse distributed receiver on Internet

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Multicast in the Internet

RP – Rendezvous pointForwarding packets destined for the multicast

group DR – Designated router

Handles multicast group membership message in it’s domain

Group

RPMS

M

S

DR

MMDR

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Multicast in Wireless Mobile Environment

Issue in Mobile Environment Multicast forwarding algorithm Dense or sparse mode protocols QoS provisioning

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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 HasRequires the HA of an MH to be a multicast router

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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 handoffSelect more than one DMSP

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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

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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

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Multicast in Wireless Mobile Environment

MMP drawback Assumes a large-scale deployment of mult

icast-capable routers in each domain Not protocol-indendpent

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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

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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

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Reliable wireless Multicast Protocols

RM2 Protocol NACK for request retransmitting

NACK: Negative acknowledgements RS manage retransmission for

fixed/mobile user or mixture of them

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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