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Stefan Engel

IP Multicast Best Practices for Enterprise Customers

Hi Everyone,

We are currently in process to review our current LAN standard templates and I'm not 100% clear on whether we should enable PIM Sparse-mode or not on all SVI's.

I understand that IGMP snooping should be enabled to avoid multicast traffic being sent to all switch ports (which is enabled by default on all/most cisco switches).

But will PIM help to improve LAN performance further (less noise) and is it general best practice to enable it on all switches?

FYI, we do not run multicast in our LAN..but of course there is always some multicast traffic.

I always tend to just enable what is really needed.

Thanks for sharing your thoughts on this.



If your not running any multicast applications that require routing across VLANs or network boundaries then you do not need it. Much of the multicast you see is probably link local and is not meant to be routed anyway.

If and when multicast routing is needed, that would be the time to implement it. Doing it now without any real reason is creating overhead in and of itself.

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You mention wanting to use IGMP snooping, but it requires an IGMP querier.  That is often provided by the multicast router; unsure whether it requires PIM to be enable on an interface.

The only "bad" thing that comes to mind, if you enable PIM, you could forward a multicast stream you don't want forwarded.