Comment 53 for bug 482419

speed/duplex auto-negotiation was not the source of the problem in my experience (not saying that it couldn't potentially cause some problem). Relying on auto-negotiation is not a good idea when using ether-channel.

What I found was that problem is originating from the udev (hotplug) ethernet system which is should be loading the bonding module prior to bringing up the bond interface. This does not happen for some reason and would require detailed inspection of uevents that are being triggered when the interfaces file is parsed.

The workaround, which I posted on 5/17/11 on related bug, 574456 [ https://bugs.launchpad.net/ubuntu/+source/ifenslave-2.6/+bug/574456/comments/5 ], is to use the pre-up scripts to explicitly state the _proper_ order things should happen. My solution works across reboots and is udev agnostic.