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From: KARCHER%MIT.MFENET@LLL-MFE.ARPA
Newsgroups: mod.computers.vax
Subject: RE: Ethernet between buildings
Message-ID: <8609010055.AA07986@ucbvax.Berkeley.EDU>
Date: Sat, 30-Aug-86 21:00:00 EDT
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Posted: Sat Aug 30 21:00:00 1986
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REPLY TO:  ETHERNET BETWEEN BUILDINGS

Fiber optic ETHERNET doesn't have to cost significantly more than coax. For
inter-building connections, fiber is the preferred choice. You will never have
to worry about grounding, noise or lightning - ever. 

Here, there are four buildings connected by 6 fiber cable ($2.20/meter) using
a star coupler and transceivers from Codenoll Technology  (of NYC). The 
transceivers (model 3030A - about $800 each) are connected between the fiber
and a DELNI in each building. All of our ETHERNET equipment (Vaxen and mixed
vendor terminal servers) is then plugged into the DELNI ports. There is not any
real ETHERNET coax involved (not yet possible with DEC optical repeaters). The
"other" ends of the fibers are connected to a centrally located optical star
coupler where the signals are mixed together and form a single ETHERNET. For a
two building setup, I believe you would not need a star coupler, just a pair of
transceivers (and DELNI's or the equivalent). 

In our case we found the major cost of inter-building ETHERNET was digging a
trench across the street and laying the conduit ($ 20K) to run the fiber cable. 
--
This information is based on the experience at our site only and is not an
endorsement of any vendor's products or services. 

C. A. Karcher                           Karcher%PFCVAX@MIT-ZERMATT.ARPA
MIT Plasma Fusion Center
Cambridge, MA