[atlas] Link aggregation for anchors?

* Gert Doering <gert at 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