[pve-devel] corosync, multicast problem because of vmbr multicast_snooping enabled

Dietmar Maurer dietmar at proxmox.com
Sat Mar 9 14:52:39 CET 2013

> Some more infos about igmp queries.
> We can have only 1 igmp quierier on a vlan. If multiple quierier exist, an election
> mecanism exist, and the querier with lowest ip should win.
> So it's possible that a proxmox host, is the igmp quierier for your whole network.
> (including physical switches).
> I think it can be pretty bad, as if you have some host problem (network driver,
> bridge bug, iptable filter,...), it can break igmp response and may cause
> potentential igmp snooping break.
> Also if you reboot the host which is the igmp quierier, a new election will occur.
> So disable igmp query on linux bridge should be disable by default.

Thoes things sound really frightening.

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