Ursula Braun wrote on 05/23/2012 04:20:43 AM:
> On Mon, 2012-05-21 at 06:41 -0500, David Boyes wrote:
> > On 5/21/12 4:11 AM, "Ursula Braun" <ubraun@linu...> wrote:
> > >
> > >we reported this problem in Novell bugzilla 617373. Solution has been
to
> > >introduce a SEND_GRATUITOUS_ARP config option. Its default is "no".
> > >Changing it to "yes" should trigger the sending of gratuitous ARPs.
The
> > >config option is offered starting with sysconfig-0.71.30-0.10.1.
> >
> > When would this NOT be the correct behavior? Seems like the default
should
> > be yes, given that that's the way ARP   has worked for decades.
>
> The solution with SEND_GRATUITOUS_ARP config option is provided by SUSE.
> They would have to change the default to "yes". We have never asked for
> this default change.

I feel compelled to point out that this discussion has been about
a Linux host using a Layer 2 interface.  If I understand the scenario
correctly, the virtual NIC is coupled to a VSWITCH which is defined
with the ETHERNET (not IP) option, so it *is* appropriate to have this
Linux host generating gratuitous ARP frames when the interface is
ready (or perhaps when the server ports are open and ready to handle
inbound requests).

When the VSWITCH is defined with the IP option, ARP responsibility
is offloaded to the OSA hardware, so the Linux host should *not* be
sending ARP frames on that interface.

This is just a reminder in case somebody using VSWITCH(IP) interfaces
finds this thread and assumes SEND_GRATUITOUS_ARP is universally
good.

Regards,
Dennis Musselwhite
z/VM CP Development

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