On 09/14/2012 03:16 PM, David Hackl wrote: > IPv6 is enabled. As I said, it works good on the node itself. I can ping > it and also ping out of it. > this is a really annoying bug in the linux bridge code. ipv6 neighbor discovery relies on multicast, and the bridge code tries to optimize multicast by not treating it as broadcast. but since v6 neighbor discovery doesn't use v4 igmp, the bridge code never realizes what bridge interfaces should get what multicast packets. the easiest fix is: echo 2 > /sys/class/net/vif#.#/brport/multicast_router with the appropriate #.# substituted (or just do them all), which tells the bridge code that there is a multicast router on that port and therefore it should receive all multicast traffic. i ran into this a few months back and had forgotten it again until now. i never found a way to make it happen at boot time, or via some script in xen, but i will now dive into that hunt again...