H3C Technologies H3C S12500 Series Switches - Manual (Page 201)

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Configuring MSDP
Overview
Multicast source discovery protocol (MSDP) is an inter-domain multicast solution that addresses the
interconnection of PIM-SM domains. It discovers multicast source information in other PIM-SM domains.
In the basic PIM-SM mode, a multicast source registers only with the RP in the local PIM-SM domain, and
the multicast source information about a domain is isolated from that of another domain. As a result, the
RP obtains the source information only within the local domain and a multicast distribution tree is built
only within the local domain to deliver multicast data from a local multicast source to local receivers.
MSDP enables the RPs of different PIM-SM domains to share their multicast source information, so that the
local RP can join multicast sources in other domains and multicast data can be transmitted among
different domains.
With MSDP peer relationship established between appropriate routers in the network, the RPs of different
PIM-SM domains are interconnected with one another. These MSDP peers exchange source active (SA)
messages, so that the multicast source information is shared among these different domains.
NOTE:
•
MSDP is applicable only if the intra-domain multicast protocol is PIM-SM.
• MSDP is meaningful only for the ASM model.
The term "router" in this document refers to both routers and Layer 3 switches.
For more information about the concepts of DR, BSR, C-BSR, RP, C-RP, SPT, and RPT mentioned in this
document, see "Configuring PIM."
How MSDP operates
MSDP peers
Configuring one or more pairs of MSDP peers in the network forms an MSDP interconnection map,
where the RPs of different PIM-SM domains are interconnected in series. An SA message sent by an RP
and relayed by these MSDP peers can be delivered to all other RPs.