Multicast over Linux bridge

Lately I’ve been working on testing multicast functionality. The quickest way to set up a multicast network has been to create several VMs and hook them together via private bridges. I’ll give a brief outline of the setup to provide some clarity, though what I should really do is provide some nice diagrams. Maybe later…

My setup consists of host A which is the VM host and the multicast sender. Hosts B and C are multicast routers with Xorp PIM router running. A, B and C are all connected to bridge br01. Hosts D and E are listeners to the multicast stream. D is connected to eth1 of B over bridge br02. E is connected to eth1 of C over bridge br03. So there is a bit of a tree being created.

Initially multicast is received properly by hosts D and E. But after 5 minutes E stops receiving any multicast data. The PIM router on C needs to be restarted to recover. After much debugging I found that multicast traffic on br01 was no longer being forwarded on to host C. The solution to this issue is detailed here. Essentially, multicast snooping needs to be disabled because PIM is not supported in the snooping.


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One Response to “Multicast over Linux bridge”

  1. Kit. Says:

    It’s probably too late to ask, but did you have an IGMP querier in your network? If you didn’t, no wonder your setup didn’t work.

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