Re: Fiber-optic Ethernet Extender


Geof Cooper (imagen!geof@decwrl.DEC.COM)
Wed, 21 May 86 10:59:36 pdt


Much thanks for the 15 or so immediate responses. To summarize, people have
mentioned that repeaters and half-repeaters (sometimes called "remote
repeaters) are available as products from DEC, Xerox, Ungerman Bass,
American Photonics (actually, this last one is a fiber extension of the
Ethernet transceiver cable (between the tap and the host)). One idea
suggested was to run low-cost ethernet coax between buildings, with a
half repeater on each side of it.

DEC's products were by far the most frequently mentioned. Several people
said they have one or the other product installed and working. There were two
products mentioned. One was the DEREP repeater, which is "intended for
exactly the type of use you describe (to link buildings where there may
be a ground potential difference, perhaps a small conduit, and a moderate
distance (I forget the max, but it is something like 1000M I think))"
[JSPEAR@AI.AI.MIT.EDU]. The other was the Lanbridge-100, which seems to
be something more like a "transparent gateway" -- it peeks at network
traffic and selectively relays information. It apparently has a fiber
optical extension available as an option.

The DEREP-RA Remote Ethernet Repeater cost $4,400 (for both halves) in
September '85. However, "it seems to be slightly divergent from the
Ethernet specs in that it only seems to work properly when connected
to the coax with a DEC transceiver (H-4000). Aside from that problem,
we've had one in use...without troubles [mckenzie@j.bbn.com].

Thanks again,

- Geof Cooper
  Imagen



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