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. Regards, Dennis