On Fri, Jun 15, 2007 at 10:11:44PM +0200, Gert Doering wrote:
> Hi,
> 
> On Fri, Jun 15, 2007 at 10:02:02PM +0200, Gert Doering wrote:
> > > > If it's a pure internal point-to-point link, you could save the effort of
> > > > maintaining ARP entries (either setting them up statically, or actually
> > > > running the ARP protocol).  Less overhead...
> > > 
> > On Fri, Jun 15, 2007 at 09:38:51PM +0200, Manuel Bouyer wrote:
> > > No. You still need to send something in the ethernet header, that will
> > > be properly received by the hardware engine on the other end.
> > 
> > "ff:ff:ff:ff:ff:ff"
> 
> Ah.  I smell a misunderstanding here - I wasn't talking about "packet
> overhead" but about "processing overhead" due to ARP handling.
> 
> The packet format cannot change, of course, but it could carry the
> broadcast MAC as destination address.

Sure. But the ARP handling overhead should be very small, as you have to
lookup the route in the routing table anyway. When arp is needed the entry
is already in the cache. Intead of a lookup in the cache you'd need a
test to see if the interface is in p2p more or not. And a similar test
in the receive path, which would not be needed otherwise.

-- 
Manuel Bouyer <bouyer@antioche.eu.org>
     NetBSD: 26 ans d'experience feront toujours la difference
--