Hi everybody, we're using Open vSwitch as it's the default software switch/bridge in XCP 1.6 (Xen Cloud Platform). As far as I know, it's version 1.4.2. I've already posted this problem to the XCP mailinglist but got no reply, so I'm trying again here :)
The following is a quote of my mail to the XCP mailinglist: We have a pool of XCP 1.6 (final) hosts using Open vSwitch. Two NICs form an active/active SLB bond for network connectivity. Recently we migrated a two node Tomcat cluster to this environment and those two VMs had a very hard time beeing reachable from the outside. After investigating the problem a bit further we learned Tomcat is using multicast for cluster communication and that's where the problem started. Open vSwitch sends out the multicast frames on ALL physical interfaces belonging to the SLB bond. That causes a lot of confusion on the physical switches that XCP hosts are connected to (VM MAC addresses jumping between ports multiple times a second). After investigating that even further, I noticed the very same problem is happening not only for multicast frames, but even for normal broadcast frames (ARP, broadcast ping, ...) - luckily Linux servers don't sent that much broadcast traffic :) We spent a few hours digging in the Open vSwitch source code and it looks like there's some special handling for broad-/multicast frames - flooding them out all ports but the port it came in (classic bridge behavior) - but there seems to be no special handling for the SLB case where I'd expect to see those packets only on the active slave for the MAC/VLAN combination of the sending VM. Hope someone can help. Best regards, Markus _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
