timk@NCSA.UIUC.EDU (Tim Krauskopf) (03/31/88)
I'm surprised that no one else has volunteered experience with Fibercom modems or other fiber used to bridge Ethernet at the MAC level. We have three fiber rings now, in use as backbones for our level-2 Ethernet (Suns). We have run as many as seven 900-1000 foot thin Ether segments off of a central ring. Until we split it, traffic from 40+ Suns traversed this ring along with a couple hundred PCs, Macs, etc. Yes, we broke all the rules, it worked for a while, now we have split it with IP routers. I think the technology is fairly straightforward. They use a proprietary ring system to emulate an 802.3 bus. Even jams and shorts are emulated across the ring. There is a lockout switch on each fiber modem which can isolate a coax segment without affecting the ring. The "documentation" says up to 2km per station, 10's of kms total ring length. We run them on fairly short runs (100m) with excellent reliability. Justifiable cost per backbone is probably in question here, but . . . "If it ain't broke, don't fix it" Tim Krauskopf timk@ncsa.uiuc.edu (ARPA) National Center for Supercomputing Applications 14013@ncsavmsa (BITNET) University of Illinois Standard disclaimer: "Just a customer"