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Date: Wed, 21 Sep 2016 19:58:56 -0700
From: Gleb Smirnoff <glebius@FreeBSD.org>
To: Ryan Stone <rysto32@gmail.com>
Cc: Kubilay Kocak <koobs@freebsd.org>, freebsd-net <freebsd-net@freebsd.org>, 
 Karl Pielorz <kpielorz_lst@tdx.co.uk>,
 Steven Hartland <killing@multiplay.co.uk>
Subject: Re: lagg Interfaces - don't do Gratuitous ARP?
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On Wed, Sep 21, 2016 at 09:12:11PM -0400, Ryan Stone wrote:
R> > IMHO, the original patch was absolutely evil hack touching multiple
R> > layers, for the sake of a very special problem.
R> >
R> > I think, that in order to kick forwarding table on switches, lagg
R> > should:
R> >
R> > - allocate an mbuf itself
R> > - set its source hardware address to its own
R> > - set destination hardware to broadcast
R> > - put some payload in there, to make packet of valid size. Why should it be
R> >   gratuitous ARP? A machine can be running IPv6 only, or may even use
R> > whatever
R> >   higher level protocol, e.g. PPPoE. We shouldn't involve IP into this
R> > Layer 2
R> >   problem at all.
R> > - Finally, send the prepared mbuf down the lagg member(s).
R> >
R> > And please don't hack half of the network stack to achieve that :)
R> 
R> The original report in this thread is about a system where it takes almost
R> 15 minutes for the network to start working again after a failover.  That
R> does not sound to me like a switch problem.  That sounds to me like the ARP
R> cache on the remote system.  To fix such a case we have to touch L3.

Does lagg(4) hardware address change when it failovers?

-- 
Totus tuus, Glebius.