Xref: utzoo comp.protocols.tcp-ip:9892 comp.unix.ultrix:2524
Path: utzoo!attcan!uunet!philmtl!philabs!zippy!brf
From: brf@zippy.Philips.Com (Bill Friday)
Newsgroups: comp.protocols.tcp-ip,comp.unix.ultrix
Subject: Re: subnet faking
Keywords: one driver two nets
Message-ID: <73671@philabs.Philips.Com>
Date: 12 Jan 90 13:52:23 GMT
References: <473@tron.UUCP>
Sender: news@philabs.Philips.Com
Reply-To: brf@zippy.UUCP (Bill Friday)
Organization: Philips Laboratories, Briarcliff Manor, NY
Lines: 40

I do not know of any way to configure one ethernet board to have to IP
addresses and be configured to route two subnets that exist on
the same wire ('ifconfig' does not permit that which define the
partameters asociated with the ethernet interface). There is something
you can try that is not very elegent but might work.

Assumptions about your net:
	1 - class 'b' address with netmask 255.255.255.0
	2 - subnet 130.140.80 and subnet 130.140.81 are connected with a
	    bridge and they need to communicate but have no route

Partial solution that might help:
	1 - This will allow direct communication between node
	    130.140.80.10 and 130.140.81.10 that live on the logical
	    network.
	2 - manually update the routing table on 130.140.81.10 with the
	    following:
	    'route add net 130.140.80 130.140.81.10 0'
	3 - manually update the routing table on 130.140.80.10 with the
	    following:
	    'route add net 130.140.81 130.140.80.10 0' 

	The above command will establish a route between the two
	specified hosts. Assume that the above nodes are sun
	fileservers. If the diskless clients had a net mask of 
	255.255.0.0 nfs works fine between the two subnets. Oh yea, the
	metric or hop count equal to zero means that the subnet is on
	the same wire in the above route commands. By routing the net
	through yoiurself it simple puts the packet on the wire. If
	could be simplifies with route defalult to yourself if not
	already used.  You could include the manual route add in 
	your '/etc/rc.local'.


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Bill Friday					UUCP: uunet!philabs!brf
Computing Resources				ARPA: brf@philabs.philips.com
Philips Laboratories				Voice (914) 945-6087
Briarcliff Manor, NY 10510
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