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Resilient Multicast options

As subject:

Looking for ways to add source resilience to multicast for audio streaming applications. Going through the Mcast Vol1 book there is a scenario of two sources and two receivers, however its unclear if the sources are distrubuting the same mcast content (which we are assuming they should be :) ). Also the model should work in an Interdomain Mcast environment using GLOP.

My thoughts on this so far are:

- Use Anycast RP to add RP resilience, with say each serving POP being a AnyRP point.

- Use IGP to advertise and select closest source to requesting receiver

What I'm struggling to understand at present is:

- what effect does this have on the MSDP sessions between each AnyRP, with each AnyRP advertising the same source details

- understanding the failover process and timings in the event of a physical source failure e.g. LAN or source machine.

Maybe Cisco want to create a TAC note on this type of thing?


Re: Resilient Multicast options

IP routing automatically will select the topologically closest RP for each source and receiver. You can traceroute to the RP address to see which router you are using.

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. Note that the RP is normally needed only to start new sessions with sources and receivers. The RP facilitates the shared tree so that sources and receivers can directly establish a multicast data flow. If a multicast data flow is already directly established between a source and the receiver, then an RP failure will not affect that session. Anycast RP ensures that new sessions with sources and receivers can begin at any time.

In Anycast RP, all the RPs are configured to be MSDP peers of each other. When a source registers with one RP, an SA message will be sent to the other RPs informing them that there is an active source for a particular multicast group. The result is that each RP will know about the active sources in the area of the other RPs. If any of the RPs were to fail, IP routing would converge and one of the RPs would become the active RP in more than one area. New sources would register with the backup RP. Receivers would join toward the new RP and connectivity would be maintained.