Path: utzoo!attcan!uunet!mcvax!inria!imag!richier
From: richier@imag.imag.fr (Jean-Luc Richier)
Newsgroups: comp.protocols.tcp-ip
Subject: gateways and more-than-one-IP-net on one ethernet
Message-ID: <3059@imag.imag.fr>
Date: 6 Jun 88 10:22:43 GMT
Reply-To: richier@imag.imag.fr (Jean-Luc Richier)
Organization: IMAG, University of Grenoble, France
Lines: 45

I have a problem with the 4.3 version of TCP-IP, when I use both gateways and
multiple nets on one ethernet.

Description:
    I have a ethernet LAN which contains 2 IP networks (In fact, it consists of
    two ethernet networks, interconnected with Level 2 Bridges).
    There is also a gateway on the LAN, which provides acess to a third network.

    The structure is as follows (with arbitrary IP numbers):

	etherLAN  IP-net-A(192.0.0.xx)  IP-net-B(192.0.1.yy)
      --------------------------+---------------------------------
				| Gateway (addr 192.0.0.1, dstaddr 192.0.2.1)
				|
				| Gateway (addr 192.0.2.2, dstaddr 192.0.0.2)
      --------------------------+---------------------------------
		etherLAN  IP-net-C(192.0.2.xx)

  The machines on IP-net-A use the route commands:
	route add network IP-net-B  0
	route add network IP-net-C 192.0.0.1 1
  The machines on IP-net-B use the route command:
	route add network IP-net-A  0

  The problem is that I cannot access the net IP-net-C from machines on
  the net IP-net-B: The route command
	route add network IP-net-C 192.0.0.1 1
   is refused, with the message "network is unreachable"

I have been unable to solve this problem with route, routed, or even by
using the "arp -s" command (trying to use proxy arp).

About 6 months ago, some persons in netland (in comp.protocols.tcp-ip)
suggested the idea of declaring more than one ethernet interface, in
order to solve the problem of more than one net on a LAN, each with
subnet and non standard broadcast addresses. I have been unable
to implement this solution (on Vax or Sun, these interfaces do not
configure, and therefore ifconfig does not work).

Is there any solution? I can think of many, but they all ask for modifications
in the kernel source. I hope that there is simpler solutions.

------------
Jean-Luc Richier
richier@imag.imag.fr or richier@imag.UUCP or uunet.uu.net!imag!richier