All things related to multicast

[Mark Boolootian <>]

I'm interested in knowing how folks deal with multicast across a
layer 2 core.  Our campus backbone currently has a layer two core which
is treated as a common backbone subnet.  While that makes traceroutes look
nice, multicast traffic floods and all the backbone router interfaces see
it, whether they need to or not.

As we roll out gigE in the backbone, the topology is moving towards a
collection of point-to-point links, so the multicast flooding over a
layer 2 core problem will go away.  Nonetheless, I'm interested in knowing
how others have dealt with this issue.  It would seem your choices are

  o Overlay the layer 2 core with layer 3 point-to-point links

  o Run the appropriate protocol for mitigating this problem.  Cisco has
    RGMP, which sounds like CGMP all over again.  Foundry, and perhaps 
    others, is doing PIM snooping, which sounds like the right way to do
    it to me.

  o Live with it.

Any experience/comments would be appreciated.

thanks,
mb
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Mark Boolootian 
UC Santa Cruz