Configuring Msdp; Overview; How Msdp Works - HP MSR1002-4 Configuration Manual

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 in each domain is isolated. As a result, both of the
following occur:
•
The RP obtains the source information only within the local domain.
•
A multicast distribution tree is built only within the local domain to deliver multicast data locally.
MSDP enables the RPs of different PIM-SM domains to share their multicast source information. The
local RP can then join the SPT rooted at the multicast source across the PIM-SM domains. This
allows multicast data to be transmitted among different domains.
With MSDP peer relationships established between appropriate routers on 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
domains.
MSDP is applicable only if the intra-domain multicast protocol is PIM-SM. MSDP takes effect only for
the ASM model.
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 works

MSDP peers
One or more pairs of MSDP peers on the network form an MSDP interconnection map. In the map,
the RPs of different PIM-SM domains interconnect in a series. An SA message from an RP is relayed
to all other RPs by these MSDP peers.
Figure 49 MSDP peer locations on the network
Source
PIM-SM 1
Router A
RP 1
MSDP peers
Receiver
Router B
RP 2
PIM-SM 3
RP 3
146
PIM-SM 2