Reference Guide

RPs advertise each (S,G) in its domain in type, length, value (TLV) format. The total number of TLVs contained in the SA is
indicated in the “Entry Count” field. SA messages are transmitted every 60 seconds, and immediately when a new
source is detected.
Figure 81. MSDP SA Message Format
Anycast RP
Using MSDP, anycast RP provides load sharing and redundancy in PIM-SM networks. Anycast RP allows two or more
rendezvous points (RPs) to share the load for source registration and the ability to act as hot backup routers for each
other.
Anycast RP allows you to configure two or more RPs 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. Because 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 operating system (FTOS) implementation of MSDP is in accordance with RFC 3618 and Anycast RP
is in accordance with RFC 3446.
Configure Multicast Source Discovery Protocol
Configuring MSDP is a four-step process.
1. Enable an exterior gateway protocol (EGP) with at least two routing domains.
Refer to the following figures.
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