Users Guide

Multicast Source Discovery Protocol

(MSDP)

This chapter describes how to configure and use the multicast source discovery protocol (MSDP).

Protocol Overview

MSDP is a Layer 3 protocol that connects IPv4 protocol-independent multicast-sparse mode (PIM-SM)

domains. A domain in the context of MSDP is a contiguous set of routers operating PIM within a common

boundary defined by an exterior gateway protocol, such as border gateway protocol (BGP).

Each rendezvous point (RP) peers with every other RP via the transmission control protocol (TCP). Through

this connection, peers advertise the sources in their domain.

1 When an RP in a PIM-SM domain receives a PIM register message from a source, it sends a source-active

(SA) message to MSDP peers, as shown in the following illustration.

2 Each MSDP peer receives and forwards the message to its peers away from the originating RP.

Multicast Source Discovery Protocol (MSDP) 678