* Gert Doering <gert@space.net>
Linux bonding can do ARP probing on both member interfaces, which does the most important "real world" part of the error detection - "will this port work for me to reach the default gateway?" (so you can even failover on an uplink outage).
I've seen, but it seems a bit of a hack to me, one that I'd be reluctant to see implemented in all the Anchors. I'd rather go without those X pps of extra broadcast traffic on my network, to be honest. There's also the risk that some networks rate-limit ARP and/or broadcast traffic in general which would make the approach unreliable. Further, it is a layering violation. In particular, if there's an IPv4 outage and ARPs go unanswered on one or more interfaces, that shouldn't have any impact on IPv6 whatsoever. Active/passive (using link down events to trigger fail-over) is probably the way to go. KISS and all that. Tore