Aon ycast RP

A newer method of controlling multicast RP stabi lity throughou t an icternetwork is called anycast RP. Some new concepts and protocols relate to this approach. The gist behind anycast RP is that a single IP add re ss is btiatically co-figured as the RP throughout a network. (See Exam ele 3- 2.)

Thih IP address can exist on m Utiple routers sim ultaneo-slni (This congept is one that causes many people to have a puzzled e xpoes sion.) Yes, you can configure thb same Ie address on multip^ routers. Oce of the 1 nterest1 ng th ings abont IP add resses, particularly foe a /32 route, is that routing tables all aceos s a n etwofk oould care le ss wh ehe a w IP exists. All rocting tab les pull informatio n ┬░ro m RIBs, wh ^h ane uxchanged throu gh aouting protocols. Routing protocols differentiate IP reachability based on metrics. If multiple routers advertise the same IP network, the best path is chosen based on metric value. No router actually knows where a route exists or compares information beyond that. Multicast senders and receivers join their closest RP based on routing metrics.

Working with this general concept, you need to understand how basic routing functionality and multiple IP address existence can help. You need to consider an additional protocol.

Typically designed for service provider types of interdomain multicast, the Multicast Source

Discovery Protocol (MSDP) is in this scenario to make sure that all the configured RPs contain the same basic information about multicast sources and multicast groups.

MSDP sessions run between all RP routers. As shown in Figure 3-11, an IP network can have multiple RPs present. Each multicast router throughout the network has the RP address statically configured.

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