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Cisco ME 3400 Ethernet Access Switch Software Configuration Guide
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Configuring MSDP
This chapter describes how to configure the Multicast Source Discovery Protocol (MSDP) on the
Cisco ME 3400 Ethernet Access switch. The MSDP connects multiple Protocol-Independent Multicast
sparse-mode (PIM-SM) domains.
MSDP is not fully supported in this software release because of a lack of support for Multicast Border
Gateway Protocol (MBGP), which works closely with MSDP. However, it is possible to create default
peers that MSDP can operate with if MBGP is not running.
To use this feature, the switch must be running the metro IP access image.
Note For complete syntax and usage information for the commands used in this chapter, see the Cisco IOS IP
Command Reference, Volume 3 of 3: Multicast, Release 12.2.
This chapter consists of these sections:
• Understanding MSDP, page 41-1
• Configuring MSDP, page 41-3
• Monitoring and Maintaining MSDP, page 41-18

Understanding MSDP

MSDP allows multicast sources for a group to be known to all rendezvous points (RPs) in different
domains. Each PIM-SM domain uses its own RPs and does not depend on RPs in other domains. An RP
runs MSDP over the Transmission Control Protocol (TCP) to discover multicast sources in other
domains.
An RP in a PIM-SM domain has an MSDP peering relationship with MSDP-enabled devices in another
domain. The peering relationship occurs over a TCP connection, primarily exchanging a list of sources
sending to multicast groups. The TCP connections between RPs are achieved by the underlying routing
system. The receiving RP uses the source lists to establish a source path.
The purpose of this topology is to have domains discover multicast sources in other domains. If the
multicast sources are of interest to a domain that has receivers, multicast data is delivered over the
normal, source-tree building mechanism in PIM-SM. MSDP is also used to announce sources sending
to a group. These announcements must originate at the domain’s RP.
MSDP depends heavily on the Border Gateway Protocol (BGP) or MBGP for interdomain operation. We
recommend that you run MSDP in RPs in your domain that are RPs for sources sending to global groups
to be announced to the Internet.