Re: [RFC] ip / ifconfig redesign

[Marc Singer <elf@buici.com>]

On Mon, Dec 05, 2005 at 06:03:02PM -0500, John Heffner wrote:
> Rick Jones wrote:
> >John Heffner wrote:
> >>Yes, but if an interface will accept packets for a certain IP address, 
> >>and will send packets with that IP address, is there any reason it 
> >>can't ARP for that address?
> >
> >
> >If ARP RFC's say it shouldn't :) (I don't know that it does) ARP is ARP, 
> >accepting IPs is IP.  The maze of twisty passages may be similar, but 
> >they are distinct.
> 
> I actually think it would be out of scope for an ARP RFC to specify this 
> (and none I'm aware of do).  It really is an IP layer decision.  That 
> is, the decision naturally extends beyond the scope of ARP, applying 
> also to layer 2 devices which don't even do ARP.

Indeed.  We've been talking about ARP responses, not queries.

> >Is a MAC address a property of the host, or of the interface connected 
> >to the host?
> 
> Depends on whether you run your interfaces in promiscuous mode, and send 
> frames with different MAC addresses from one interface. ;-)

MAC addresses are owned by the link.  It is not meaningful for eth1 to
transmit the MAC for eth0.  Consider that both interfaces could be on
the same link.

Yes, we can do all manner of gymnastics, but this is something that
IEEE standardizes.