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From: root@bu-cs.UUCP (Barry Shein)
Newsgroups: net.lan,net.dcom
Subject: Re: ETHERNET on Broadband
Message-ID: <454@bu-cs.UUCP>
Date: Mon, 1-Jul-85 20:21:47 EDT
Article-I.D.: bu-cs.454
Posted: Mon Jul  1 20:21:47 1985
Date-Received: Fri, 5-Jul-85 04:01:07 EDT
References: <2926@decwrl.UUCP> <449@bu-cs.UUCP>, <1263@opus.UUCP>
Organization: Boston Univ Comp. Sci.
Lines: 49
Xref: watmath net.lan:899 net.dcom:1077

Re: DR11-W--U/B NIU-150 --Broadband (Ungermann/Bass Broadband
driver for 4.2,VMS at Boston University.)

Just to clarify (a comment made by a poster indicated some confusion):

The reason I entered this into the discussion was because our
broadband interfaces *do* act as ethernet/broadband bridges,
exactly like you would hope. We have two 4.2 vaxes with both an
ethernet (DEUNA) and U/B Broadband interface which act as transparent
gateways for other non-broadband hosts, for example:

 Eng Vax	     IBM3081	C.S. Student Vax  C.S. Research Vax  DEC2060
broadband | street | ethernet     ethernet only   ethernet+broadband ethernet
  only		       only					       only

Every system in the picture can TELNET, FTP, SMTP etc to every other
system in the picture as if they were on one ethernet (although because
they form logically distinct subnets broadcasts have to be forwarded,
like two ethernets.) I hope this clarifies something.

No, does not require a DEC system, we are soon to move it to a SUN, any
4.2bsd system with sources and a DR11-W or DR11-B compatible interface
would do (MultiBus,VMEbus DR11-W emulators exist.) You only need one
such system per ethernet anyhow which acts as a gate. It only takes one
channel on the broadband which is important to us.  We will look into
other interfaces such as RS232 and V.35 also to lessen the DR11-W
constraint (U/B would probably have some ideas, they make several
interfaces.)

Yes, I would like a black box that just snapped onto an ethernet cable
and broadband tap and magically forwarded to another, remote box with
the same connections, but I don't like the idea of 2 or 3 dedicated
channels to do it. I also wonder exactly what gets forwarded (every
packet? the DEC box certainly doesn't read IP packets.)  I guess for now
I am using a couple of Vaxes as this 'black box'.

I could imagine buying a cheap 68K 4.2 box, adding a parallel and
ethernet interface and configuring in the driver and our campus' routing
tables and thus acheiving this, tho probably a little expensive (well, a
bit less than $10,000 for sure.) And hell, a few people could log into
it also, or it could be expanded to be a print server or some such.
(note that we have yet to see a performance problem, packets get
forwarded thru 4.2 very cheaply.)

Nah, we looked at the DEC broadband box as we were writing our own.
Unless you are locked into DecNet we didn't think it was a very good
solution at all, tho I will admit the choices are limited.

	-Barry Shein, Boston University