Subject: problem with 2 different ip subnet on same ethernet
To: Manuel Bouyer <bouyer@lix.polytechnique.fr>
From: Jonathan Stone <jonathan@DSG.Stanford.EDU>
List: tech-net
Date: 08/01/1996 15:07:19
>I have a ip subnetwork on an ethernet (129.104.11.0). On this ethernet
>I've installed a solaris machine, with ip adress 192.168.1.1.
>On my NetBSD/pmax (129.104.11.53), I've done
>n'route add -host 192.168.1.1 -interface 129.104.11.53'.

[results in "can't allocate llinfo" message]

I couldn't get a similar configuration  to work, either.
More on that below.

Another way to do waht you want is to configure two subnets on one
cable. Configure at least one machine to route between them, e.g.,
on the NetBSD machine, do

	ifconfig le0 inet 192.168.1.<hostpart> netmask <mask> alias

then at least the netbsd machine will be  able to reach the Solaris
machine. You can then configure other machines to use the NetBSD
machinea as a gateway, if you wish.

I've run into several inconsistencies and buglets like this recently.
The PATRICA-tree routing table (merged route/arp table) can support
things like this, and like arp-for-subnets.  However, there is a
"death of a thousand cuts" with  hidden assumptions and old, obsolete
routing-table updates inside the kernel.

Someone is working on redoing arp.  Maybe host routes out an Ethernet
interface will work sometime after 1.2. I wouldn't bet on it
though....

--Jonathan