JUNOS Enterprise Routing

PIM-Based Anycast-RP

The final multicast configuration exercise in this chapter involves deployment of Anycast-RP, with emphasis on a PIM-only solution. An alternative configuration using MSDP is also provided.

With both auto-RP and BSR, only one RP is permitted to be active for any given group at any one time. Anycast-RP relaxes this restriction and allows multiple RPs to be active for the same group at the same time. Anycast-RP requires a mechanism by which the multiple RPs share information about active sources. This inter-RP communication has historically been performed by MSDP, but JUNOS software also supports the PIM-only Anycast-RP solution, as specified in RFC 4610. The PIM-based solution is attractive because it eliminates all need for MSDP within an organization, allowing MSDP deployment as needed, and then only for its original purpose of interdomain multicast support.

Because of the common RP address that is shared among all the RPs, receivers simply send their joins to the metrically closest Anycast-RP, and they are unaware of the presence of multiple RPs.

The configuration objectives are as follows:

• Stout and Bock remain RPs, but both must now use 10.255.255.1 for RP functionality.

• Do not use BSR or auto-RP.

• Ensure no single points of failure.

The requirement that no dynamic RP discovery mechanisms be used may strike you as a bit odd, especially in light of the need for network resiliency to single points of failure. Recall that with Anycast-RP, all of the RPs for a given ...