Sparse-Dense with Sparse will Work ?

Unanswered Question
Oct 20th, 2009


I have customer Netwrok Running Sparse-Dense multicast, and we will implement Nexus 7000 ( Which supports Sparse only).

So can we configure Sparse on Nexus to work with The existing Sparse-Dense ?

If Yes, What is configuration shoud be done on the New Switches ?


I have this problem too.
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Giuseppe Larosa Tue, 10/20/2009 - 03:29

Hello Mohamed,

sparse-dense-mode works on a per group basis for all groups that have an RP serving it behaves like sparse-mode.

sh ip pim rp mapping tells you for what groups there are RPs.

you may be interested in the global command

no ip pim dm-fallback

to avoid fallback to dense mode.

Hope to help


seegomaa Tue, 10/20/2009 - 04:41

Thanks Giuseppe for your reply

My question is: On the Existing PIM Configuration Sparse-dense is there, and on the new Nexus i have Sparse only, How can i make Sparse on Nexus work with the Existing Sparse-Dense ?

Thanks again for your answer

Giuseppe Larosa Tue, 10/20/2009 - 06:02

Hello Mohamed,

as I have written in my first post, interaction should be fine for all groups treated as sparse mode.

if all your multicast traffic is in sparse mode.

sparse-dense-mode is used by autoRP to allow propagation of mapping messages on and

if you have user traffic in groups treated as dense mode this can be a problem


You need to verify if sparse-dense mode is used only for autoRP or also for user traffic.

Hope to help



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