Reference Guide

Multicast Source Discovery Protocol (MSDP) | 539
evenly spaced around the network, an equal number of sources register with each RP.
Consequently, all the RPs in the network share the process of registering the sources equally. Since a
source may register with one RP and receivers may join to a different RP, a method is needed for the RPs to
exchange information about active sources. This information exchange is done with MSDP.
With Anycast RP, all the RPs are configured to be MSDP peers of each other. When a source registers with
one RP, an SA message is sent to the other RPs informing them that there is an active source for a
particular multicast group. The result is that each RP is aware of the active sources in the area of the other
RPs. If any of the RPs fail, IP routing converges and one of the RPs becomes the active RP in more than
one area. New sources register with the backup RP. Receivers join toward the new RP and connectivity is
maintained.
Implementation Information
• The FTOS implementation of MSDP is in accordance with RFC 3618 and Anycast RP is in accordance
with RFC 3446.
Configuring Multicast Source Discovery Protocol
Configuring MSDP is a three-step process:
1. Enable an exterior gateway protocol (EGP) with at least two routing domains.
• Figure 28-5 and MSDP Sample Configurations on page 560 show the OSPF-BGP configuration
used in this chapter for MSDP. Otherwise, Refer to Chapter 31, Open Shortest Path First (OSPFv2)
and Chapter 8, Border Gateway Protocol.
2. Configure PIM-SM within each EGP routing domain.
• Figure 28-5 and MSDP Sample Configurations show the PIM-SM configuration in this chapter for
MSDP. Otherwise, Refer to Chapter 32, “PIM Sparse-Mode (PIM-SM),” on page 619.
3. Enable MSDP. Refer to page 545.
4. Peer the RPs in each routing domain with each other. Refer to Enable MSDP.
Related Configuration Tasks
• Enable MSDP
• Manage the Source-active Cache
• Accept Source-active Messages that fail the RFP Check
• Limit the Source-active Messages from a Peer
• Prevent MSDP from Caching a Local Source
• Prevent MSDP from Caching a Remote Source
• Prevent MSDP from Advertising a Local Source
• Terminate a Peership