lagg Interfaces - don't do Gratuitous ARP?

[Gleb Smirnoff]

On Sat, Sep 10, 2016 at 10:51:36PM +1000, Kubilay Kocak wrote:
K> > <killing at multiplay.co.uk> wrote:
K> > 
K> >> Yes known issue I'm afraid.
K> >> 
K> >> I created a patch set to address this but there where objections so
K> >> it was removed, see the attached which is based on 10.2-RELEASE.
K> > 
K> > Hi,
K> > 
K> > Thanks for the reply, and the comprehensive patch. If I get a chance 
K> > I'll see if I can run it up one of the affected boxes, if I can find
K> > one I can mess around with.
K> > 
K> > Good to know it wasn't just "me" :)
K> > 
K> > Cheers,
K> > 
K> > -Karl
K> 
K> Also see the following review, which was re-opened (after original
K> commit was reverted) after said issues were raised, though I can't see
K> that glebius has commented on it since:
K> 
K> https://reviews.freebsd.org/D4111
K> 
K> 11.0 having this would have been awesome. Maybe (hopefully) 11.1

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 :)

-- 
Totus tuus, Glebius.