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From: root%bostonu.csnet@csnet-relay.arpa (BostonU SysMgr)
Newsgroups: fa.tcp-ip
Subject: Re:  interesting loop
Message-ID: <8508302018.AA25441@UCB-VAX.ARPA>
Date: Fri, 30-Aug-85 13:22:22 EDT
Article-I.D.: UCB-VAX.8508302018.AA25441
Posted: Fri Aug 30 13:22:22 1985
Date-Received: Sat, 31-Aug-85 21:23:22 EDT
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Re: Packet loops caused by dumb broad/base band gateways

This is one of the major reasons why at Boston University we
chose to put our broad/base band gateways into our 4.2 hosts,
we use Ungermann/Bass Net/1 DR11-W (soon SUN also) NIUs.
The 4.2 hosts then are just typical gateways and are
intelligent about IP and our broadband interfaces are
completely analagous to our baseband (eg. they support ARP.)

For reliability we have more than one 4.2 host on our baseband
with broadband interfaces. Routed (with the bugs removed) takes
care of transitions for us, it all works quite smoothly and
I have not yet detected it to cause any load. Further, those
hosts with broadband interfaces just talk to each other directly
under this scheme, rather than routing over ethernets.

I was always very suspicious about this mindless gateway approach
for this and a few other reasons, like what happens to your broadcast
packets? I am sure there is a reasonable solution to this, but
utilizing the broadband directly seemed the way to go.

If I needed to add PUP or XNS I am pretty sure it would just be a
'typical' job to recognize those packets need to be forwarded in
the drivers. If I needed to gateway DECNET, I would tell them
too bad, I told you to stay away from it (I am anticipating a
response viz a viz the need to support other protocols on the system.)
We in fact can give our DECNET hosts 19.2kb synchronous p-p interfaces
on our broadband cable which is about all they can expect.

	-Barry Shein, Boston University