Subject: Re: [RFC] ip / ifconfig redesign

From: Marc Singer <[email-masked]>
Date: Mon, 5 Dec 2005 13:03:29 -0800

On Mon, Dec 05, 2005 at 10:00:41AM -0800, Ben Greear wrote:
> >Precisely the case.  It should be the case that a box response to an
> >arp on *any* interface for *any* IP address known to the box.
> 
> I certainly don't mind if this is a configurable, or even default
> behaviour, but we also need the ability to only respond to particular
> arps on particular interfaces, based on the IP addresses assigned
> to those interfaces.

Why?  The routing determines connectivity, not ARP.  AFAIK, ARP
requests are not made on interfaces that lack that the network being
queried.

If I put a host with an address on network 12 onto an ethernet segment
for network 10 and then ARP for addresses on network 10, I ought to be
able to send packets to those hosts (baring a firewal).  However, I
won't be able to get anything back because those hosts don't know how
to send to network 12.  Misconfiguration?  Yes.  Non-compliant?  No.

> I am able to get this particular arp binding working today, so I'm
> not suggesting changes, just mentioning that there are other
> configurations than what you mention that are useful to people.

Anyway, I haven't seen a good reason to change the current behavior.
While the above described functionality is missing, no one has made a
case to support it.