Re: [libvirt-users] multicast traffic no longer working after reboot

On 31.07.2014 15:14, Dennis Jacobfeuerborn wrote: > Hi, > today a couple of Hypervisors got restarted due to a power outage. While > the systems and the VMs on the are running fine multicast traffic > between the guests is no longer working. > > I generate multicast udp packet using iperf in the guest and check on > the host using tcpdump: > > tcpdump vnet0 => multicast packets are visible > tcpdump vlanbr8 => multicast packets are visible > tcpdump em1.8 => no multicast packets visible > > vlanbr8 is the bridge, vnet0 the interface of the guest and em1.8 the > physical interface for vlan 8. > > I compared the settings in /sys/class/net/vlanbr8/bridge/multicast_* > with a system where multicast works fine and see no differences. brctl > showstp also shows "mc router" to be 1 for both interfaces and the > bridge. All settings in /proc/sys/net/bridge/* are 0. > > Any ideas why the bridge doesn't seem to forward multicast packets? > iperf with unicast udp also works fine so it's just multicast that is > the problem. I did some further testing and strangely enough after booting the HV and the guest things work as expected but after 2-3 minutes I suddenly don't see the the packets anymore on em1.8. This is really bizarre behavior.