[ovs-dev] [PATCH] lacp: Select a may-enable IF as the lead IF

[Ben Pfaff]

On Thu, Dec 01, 2016 at 02:01:59PM +0100, Torgny Lindberg wrote:
> A reboot of one switch in an MC-LAG bond makes all bond links
> to go down, causing a total connectivity loss for 3 seconds.
> 
> Packet capture shows that spurious LACP PDUs are sent to OVS with
> a different MAC address (partner system id) during the final
> stages of the MC-LAG switch reboot.
> 
> The current code selects a lead interface based on information
> in the LACP PDU, regardless of its synchronization state. If a
> non-synchronized interface is selected as the OVS lead interface
> then all other interfaces are forced down as their stored partner
> system id differs and the bond ends up with no working interface.
> The bond recovers within three seconds after the last spurious
> message.
> 
> To avoid the problem, this commit requires a lead interface
> to be synchronized. In case no synchronized interface exists,
> the selection of lead interface is done as in the current code.
> 
> Signed-off-by: Torgny Lindberg <torgny.lindberg at ericsson.com>

I think I understand what's going on here now.  I made some changes that
better reflect my understanding:
        https://mail.openvswitch.org/pipermail/ovs-dev/2016-December/326567.html
Does this work for you?  If so, I'll apply it.

Thanks,

Ben.