lagg Interfaces - don't do Gratuitous ARP?

[Ryan Stone]

On Wed, Sep 21, 2016 at 7:57 PM, Gleb Smirnoff <glebius at freebsd.org> wrote:

> IMHO, the original patch was absolutely evil hack touching multiple
> layers, for the sake of a very special problem.
>
> I think, that in order to kick forwarding table on switches, lagg
> should:
>
> - allocate an mbuf itself
> - set its source hardware address to its own
> - set destination hardware to broadcast
> - put some payload in there, to make packet of valid size. Why should it be
>   gratuitous ARP? A machine can be running IPv6 only, or may even use
> whatever
>   higher level protocol, e.g. PPPoE. We shouldn't involve IP into this
> Layer 2
>   problem at all.
> - Finally, send the prepared mbuf down the lagg member(s).
>
> And please don't hack half of the network stack to achieve that :)
>

The original report in this thread is about a system where it takes almost
15 minutes for the network to start working again after a failover.  That
does not sound to me like a switch problem.  That sounds to me like the ARP
cache on the remote system.  To fix such a case we have to touch L3.