Hi,
I have a Centos VM running on a Ubuntu 12.04 (kernel 3.2 / qemu 1.1) host connected via a bridged tap interface. This setup works perfectly fine with my multicast configuration, but fails on a Ubuntu 13.04 setup (kernel 3.8 / qemu 1.4). My problem is that multicast drops out exactly 5 minutes after the sockets are created. Besides the obvious kernel and qemu version differences, the only real difference I can see is that the VM on the 12.04 host is using IGMP v2. I've tried to force the 13.04 host to use v2 on all interfaces, but the VM always seems to pickup v3. It's likely I'm barking up the wrong tree, but I figured I'd ask if there was a way to force the qemu tap interface to use IGMP v2.
It's uncanny that multicast dies out at exactly 5 minutes. I figure I'm hitting some timeout threshold, but like I said everything works fine on the 12.04 host.