Wednesday, July 18, 2012

Open vSwitch active-passive failover - unreachable guests

The current release of Open vSwitch (1.6.1) does not send learning packets when doing an active-passive bond failover. Switches connected to your network interfaces will not now about the network change when LACP is not used. Result: all your virtual machines machines become unavailable until your guests send out packages that updates the MAC learning table of the uplink switches or until the entry expires from the learning table.

The next release (1.7?) will include a patch to send learning packets when a failover happens. I tested the patch by doing a manual failover on the host and having the interfaces connected to 2 different switches:

# ovs-appctl bond/show bond0
# ovs-appctl bond/set-active-slave bond0 eth1

Hooray! Not a single interruption in guest connectivity... like it should be :-)

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