nawas Thu, 06/11/2009 - 07:59


Is there a benefit to run anycast RP ie MSDP vs running an RP and done with it. Is there any other simplest form of configuring the multicast in the enterprise?

Harold Ritter Thu, 06/11/2009 - 08:29


The big advantage of anycast RP is that it offers the simplicity of static RP and it also provides redundancy, which you don't get with static RP.


nawas Tue, 06/16/2009 - 07:10

Ok, here is I want to do, please let me know if I'm doing it right. I have a corporate office buidling with about 2000 users, this office has two core 6509 which connects to the core in the data center. I want to enable msdp on the two core and will have multicast servers and users connected to the same core (in the corporate office).

Now I have several remote offices and each remote office has a Cisco 6509 which connects to a WAN router in the data center. I'm thinking enabling msdp on 6509 in the remote as well but how do I configure this only on one router. My whole goal is to keep the multicast off from the data center and let each site talk to multicast on their own router and unicast to the remote sites. Please let me know.


Harold Ritter Tue, 06/16/2009 - 10:12


It is not common practice to run so many RPs unless the network is quite large.

About your point to keep the multicast in the remote site, bear in mind that no traffic will go from the remote site to the DC, assuming both the sources and the receivers are in the remote sites.

Where are the multicast sources?


nawas Tue, 06/16/2009 - 10:18

Source will be at each location. I plan to put one multicast server as each remote location, lets says site A has an RP and it also has a multciast server x.x.x.x and site B has an RP and has a multicast server y.y.y.y. That way multicast will stay at its own site. Possible or a bad design?

Harold Ritter Tue, 06/16/2009 - 10:45


My point is that you don't need to have an RP per remote location to keep the multicast traffic sourced in that location local. If both the source and the receivers are connected to the 6500 in the remote location and that there is no receivers elsewhere interested in the multicast stream, that stream will remain local.

I think having two RPs configured for Anycast RP would be sufficient.


Giuseppe Larosa Tue, 06/16/2009 - 10:53

Hello Nawaz,

you generally don't need to deploy a RP on each remote site.

If your remote sites are multihomed you can deploy an anycast RP solution only on the central site core switches.

It looks like you are worried of what can happen if a remote site is isolated and you want to support multicast on it also in this case.

You can use ip pim sparse-dense-mode and a dynamic mapping like bootstrap protocol with anycast RP.

When the remote site is isolated dynamic mapping fails and the site falls back to dense mode that can be acceptable.

Hope to help



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