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From: pjw@anucsd.OZ (Peter Wishart)
Newsgroups: net.dcom,net.lan
Subject: Ethernet between buildings?
Message-ID: <408@anucsd.OZ>
Date: Wed, 16-Oct-85 01:29:01 EDT
Article-I.D.: anucsd.408
Posted: Wed Oct 16 01:29:01 1985
Date-Received: Fri, 18-Oct-85 00:38:47 EDT
Organization: Computer Science, Australian National University
Lines: 28
Xref: watmath net.dcom:1384 net.lan:1096

Our department is about to move to another building.   In our current
current building we have an ethernet with VMS Vaxen (using DECnet) and
Suns and a Pyramid (using IP) on it.  We wish to run our ethernet
connection from our new building to the old and have both DECnet and IP
running between the builings.  All the Suns and the Pyramid will be in
the new building plus a VMS 750, the old building will keep numerous
VMS Vaxen and a Unix 4.2BSD Vax.  The distance between the buildings is
about 100 meters [of open ground].

The problem is to protect the ethernet (i.e. the machines on it)
between the buildings from bizarre things like lightning strikes. 
DEC (Australia) are insisting the only way to do it is to install a
fibre optic link with bridges at both ends.  This looks like costing us
upwards of $25K (Australian).  This seems to be excessive for just a
link between buildings!

We are looking for a cheaper way of doing this.  We recently tested a
small device purporting to be "an ethernet fuse" (it "breaks" the
ethernet when a significant voltage is found on the cable), but it
degraded the performance so badly we had to reject it.  How does one
normally run an ethernet between buildings?  Can you provide enough
shielding for the cable so that bridges etc are not necessary?  
Help ...

Peter Wishart	    Computer Science, Australian National University, Canberra

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