Reference Guide

Multicast Source Discovery Protocol (MSDP) | 581
Anycast RP allows two or more RPs to be configured with the same IP address on loopback interfaces. The
Anycast RP loopback address are configured with a 32-bit mask, making it a host address. All downstream
routers are configured to know that the Anycast RP loopback address is the IP address of their local RP. IP
routing automatically selects the closest RP for each source and receiver. Assuming that the sources are
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 Dell Networking OS 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 31-5 and MSDP Sample Configurations on page 601 show the OSPF-BGP configuration used
in this chapter for MSDP. Otherwise, see Chapter 35, Open Shortest Path First (OSPFv2) and
Chapter 9, Border Gateway Protocol IPv4 (BGPv4).
2. Configure PIM-SM within each EGP routing domain.
Figure 31-5 and MSDP Sample Configurations show the PIM-SM configuration in this chapter for
MSDP. Otherwise, see Chapter 36, “PIM Sparse-Mode (PIM-SM),” on page 683.
3. Enable MSDP. See page 587.
4. Peer the RPs in each routing domain with each other. See Enabling MSDP.
Related Configuration Tasks
• Enabling MSDP
• Managing the Source-active Cache
• Accepting Source-active Messages that fail the RFP Check
• Limiting the Source-active Messages from a Peer
• Preventing MSDP from Caching a Local Source
• Preventing MSDP from Caching a Remote Source
• Preventing MSDP from Advertising a Local Source