Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!emory!stiatl!bagend!bvsatl!root
From: root@bvsatl.UUCP (Super user)
Newsgroups: comp.unix.questions
Subject: Re: Getting 4.2BSD to Understand Subnetted Network
Summary: proxy arp and older (sub-network dumb) hosts
Message-ID: <183@bvsatl.UUCP>
Date: 7 Jan 91 19:32:15 GMT
References: <1873@fallst.UUCP>
Organization: bvsatl   Atlanta Ga.
Lines: 28

In article <1873@fallst.UUCP>, tkevans@fallst.UUCP (Tim Evans) writes:
> 4.2BSD seems not to understand subnetting, so the
> first such machine on the net sees only itself and a few
> others (386's with an older TCP/IP) which also don't understand
> subnetting.
> 
> What can be done with 4.2BSD to make things work?
> 
> PLEASE NOTE:  As indicated above, we do not have source for
> 4.2BSD.  (Long story, not appropriate here.)

Assuming that you are using a decent router to connect your subnets,
it should be able to proxy arp for the hosts on a different subnet
than the B42 hosts. In other words, configure your router to
reply with its ethernet address whenever it sees an arp request
on a subnetwork that it does not belong on. This way, the older
hosts will think that the whole network lives on the one ethernet
cable and the routers will take care of the rest.

Obviously a better solution is to upgrade the hosts, but we all
know how that goes (8-)).

Bill VerSteeg

-- 
Bill VerSteeg
internet	bvs@nrc.com
UUCP		gatech.edu!galbp!bagend!bvsatl!bvs