3Com Switch 7750 Configuration Guide Guide

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MSDP CONFIGURATION
Overview
Introduction to MSDP Internet service providers (ISP) are not willing to rely on devices of their
competitors to forward multicast traffic. On the other hand, ISPs want to obtain
information from information sources no matter where the information resources
reside and forward the information to their own members. MSDP is designed to
address this issue and used to discover multicast sources in other protocol
independent multicast sparse mode (PIM-SM) domains. MSDP is only valid for the
any-source multicast (ASM) model.
MSDP describes a mechanism of interconnecting multiple PIM-SM domains. It
requires that the inter-domain multicast routing protocol must be PIM-SM and
allows the rendezvous points (RPs) of different domains to share multicast source
information.
MSDP peers
The RP in a PIM-SM domain can sense the existence of an active multicast source
S, if any, in this domain through multicast source register messages. If a PIM-SM
domain managed by another ISP wants to obtain information from this multicast
source, the routers in both PIM-SM domains must establish an MSDP peering
relationship with each other, as shown in
Figure 105:
Figure 105 MSDP peering relationship
n
MSDP peers are interconnected over TCP connections (through port 639). A TCP
connection can be established between RPs in different PIM-SM domains,
RP1
Source
RP2
RP4
RP3
PIM-SM 1
PIM-SM 2
PIM-SM 3
PIM-SM 4
user
user
user
SA
SA
SA
SA
SA
SA message
MSDP peers
Join
Join