$JCH@CLVM.BITNET (Jeffrey C Honig) (08/29/86)
One of our departments is installing some diskless Sun workstations in two buildings with a Sun file server in another. This of course necessitates the use of Ethernet between the buildings (which are right next to each other). Up here in Northern NY we get alot of thunderstorms during the summer and fall (especially this year!) and are worried about lightning damage. We asked Sun for Ethernet configurations guidelines and were sent a copy of DEC's "Ethernet Installation Guide". This manual recommends that Fiber be used between buildings because it "Eliminates any potential interbuilding grounding problems". We know there are no grounding problems. DEC does does give information about running baseband between buildings but does not even mention lightning arrestors. The department doesn't want to spent the 10k to use fiber but I don't want to recommend that they use baseband until I see some written documentation on lightning protection. Does anyone have any experience in this area or can anyone recommend some specifications that deal with the subject? Thanks much Jeffrey C Honig Schuler Educational Resources Center Clarkson University Potsdam, NY
KARCHER%MIT.MFENET@LLL-MFE.ARPA (08/31/86)
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