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From: djh@cci632.UUCP (Daniel J. Hazekamp)
Newsgroups: comp.protocols.tcp-ip,comp.dcom.lans
Subject: How can I force some routes through an Ethernet Bridge??
Keywords: Ethernet Bridge TCP/IP 4.2BSD Networking
Message-ID: <29219@cci632.UUCP>
Date: 15 Jun 89 15:20:43 GMT
Organization: CCI, Communications Systems Division, Rochester, NY
Lines: 84

First, the scenario:

	We have 2 local ethernets with different Class C internet addresses
connected via a gateway host. A single host on Net A, has some leased line
connections to additional offsite ethernets. All hosts are running 4.2 BSD
Networking software.


			      Net B
	----------------------------------------------------
				|
			   -----------
			   |  local  |
			   | gateway |
			   |   host  |
			   -----------
				|
	----------------------------------------------------
			      Net A		|
					   -----------
					   |  remote |
					   | gateway |
					   |   host  |
					   -----------
	leased lines to offsite Nets   ---->  |   |



I've replaced the 'local gateway host' with an ethernet bridge.

			      Net B
	----------------------------------------------------
				|
			   -----------
			   | ethernet|
			   |  bridge |
			   -----------
				|
	----------------------------------------------------
			      Net A		|
					   -----------
					   |  remote |
					   | gateway |
					   |   host  |
					   -----------
	leased lines to offsite Nets   ---->  |   |
	
I then added routing information to allow hosts on Nets A and B to talk to
each other through the bridge.

		On Net B hosts:
			/etc/route add NetA NetB 0

		On Net A hosts:
			/etc/route add NetB NetA 0

At this point, telnet, ftp, rlogin, etc all work between hosts on Nets A and B.

The problem is that I can't get to any hosts on the offsite networks from Net B
hosts. Under the original setup, I assigned the 'default' route to the 'remote' 
gateway host as follows:

		/etc/route add default rgateway 1

With the new setup, this fails on all the Net B hosts, even though I have a
valid route to Net A. The error message returned is 'Network Unreachable'. This
is clearly bogus, since I can rlogin, ftp, etc to all the Net A hosts.

Any help would be appreciated.

Note: I realize that one solution is to modify the setup such that Nets A and B
are simply 2 segments with the same Class C net address. We'd like to avoid this
if at all possible.

Dan Hazekamp
Computer Consoles Inc.
Rochester, NY

UUCP:		rochester!cci632!djh
Internet:	cci632!djh@cs.rochester.edu
-- 
Dan Hazekamp					rochester!cci632!djh
Computer Consoles Inc. (CCI)			uunet!ccicpg!cci632!djh
Rochester, NY					uunet!rlgvax!cci632!djh