On Mon, Sep 08, 1997 at 03:05:43PM -0700, Curt Sampson wrote:
> Why not just set up a /30 subnet for this instance?

I said *two* single IP adresses. The adresses may not be in a single
/30 block maybe not even in the same /24 network.

> Having a way to change the semantics of Ethernet or whatever it is you
> happen to be using seems a bit....pointless.

I must object. I know a NetBSD user who is forced to use a horrible
tunneling construction because NetBSD doesn't support this. He got
2 IP address from our Univerity (.83 and .84, obviously not in the
same /30 block) for his leased line, one is used for the router at the
University the other one for it's NetBSD system. The first solution which
cames to one's mind is something like this:

	remote-router <-ISDN->	local-router <-Ether->	NetBSD box 1
	x.y.z.83		192.168.0.1		192.168.0.2
							    +
							x.y.z.84 as IP alias

But this solution won't work because the NetBSD box would use 192.168.0.2
as source IP address for all outgoing packets. With the ability to use
Ethernet in point to point mode - Linux can handle this btw - he could
use this solution:

	remote-router <-ISDN->	local-router <-Ether->	NetBSD box 1
	x.y.z.83		192.168.0.1	P2P	x.y.z.84

Because NetBSD can't do this his solution looks like this:

	remote-router <-ISDN->	local-router <-Ether->	NetBSD box 2
	x.y.z.83		192.168.0.1		192.168.0.2
							    +
				NetBSD box 1 <-Ether->	192.168.1.2
				192.168.2.1		    ^
				    +			    |
				x.y.z.84	---tunnel---+

And I could describe you another scenery where I needed this feature, too.

-- 
Matthias Scheler                                http://home.owl.de/~tron/