geoffb@nrcvax.UUCP (G. Geoffrey Baehr) (11/07/85)
Keywords:fiber repeater
A short follow up to the net on the article I posted concerning Fiber
Optic Repeaters for Ethernets.
Another vendor has come on the scene :
Fiber Com
Box 11966
Roanoke, Virginia 24022-1966
703-342-6700
Their repeater is similar to many of the others, yet it is TEMPEST
certified. This leads to an interesting paradox - why TEMPEST certify
the box which is attached to an unsecured net, with non TEMPEST
tranceivers ?? Someone must need this certification...
Price quoted by an eager sales type was approx 895/per.
As usual, other people's experiences and recommendations are welcome. I hope
that this helps to reduce the morass of information out there to mere primeval
ooze.
--
Geoffrey Baehr - N6LXA Network Research Corp
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POST - 2380 N Rose Ave. Oxnard C.A. 93030
-------------------------------------------------------------------------------tcs@usna.UUCP (Terry Slattery <tcs@usna>) (11/11/85)
From postnews Sun Nov 10 21:47:18 1985 > A short follow up to the net on the article I posted concerning Fiber > Optic Repeaters for Ethernets. > > Another vendor has come on the scene : > Fiber Com The strategies used by Fiber Com differ considerably from those used by Codenoll and Siecor. The FiberCom network is really a ring in which a single uni-directional fiber connects all xcvrs into a ring. The maximum distance between xcvrs is something like 1 or 1.5 km (my literature is at work). If an xcvr fails, a relay couples the input and output fibers. I havn't had the pleasure of opening one up so I can't say how it's done. The Codenoll and Seicor products both use transmissive star couplers at the center of a star configuration. Codenoll's product is totally passive. The optical signals must be within 4db for collisions to be detected so detailed flux budgeting must be done. Maximum arm to arm distance is 1.5Km with either a 4 or 8 port star available. Seicor goes one step further in that they use an active sensor at the star to sense collisions and then broadcast a collision signal (increasing the probablity of sensing a collision.) Fiber Com probably does well in point-to-point stuff and the others in places where several buildings need to be interconnected. I'm in the process of installing the Codenoll stuff here. I should know more in another couple of weeks or so. -tcs Terry Slattery U.S. Naval Academy 301-267-4413 ARPA: tcs@brl-tgr.arpa UUCP: decvax!brl-bmd!usna!tcs
wb6rqn@yojna1.UUCP (Brian Lloyd) (11/13/85)
> [...] yet it is TEMPEST > certified. This leads to an interesting paradox - why TEMPEST certify > the box which is attached to an unsecured net, with non TEMPEST > tranceivers ?? Someone must need this certification... > > [...] > > Geoffrey Baehr - N6LXA Network Research Corp > I have had the unfortunate experience of dealing with the TEMPEST environment. You are allowed to operate non-TEMPEST equipment in a TEMPEST-required environment if the building is fully shielded. Imagine someone running an Ethernet within a shielded room/building and wishing to connect to another such Ethernet somewhere else, where the interconnection must pass through a non-shielded area. In this case it makes sense to have a TEMPEST connection between two non-TEMPEST LANs. Brian Lloyd ...![bellcore!cp1]!yojna1!wb6rqn