Path: utzoo!utgpu!water!watmath!clyde!rutgers!husc6!bu-cs!kwe
From: kwe@bu-cs.BU.EDU (kwe@bu-it.bu.edu (Kent W. England))
Newsgroups: comp.dcom.lans
Subject: Re: Multi-mode or single-mode fiber -- which is best for FDDI?
Summary: Multimode is best for now
Message-ID: <19210@bu-cs.BU.EDU>
Date: 25 Jan 88 18:18:35 GMT
References: <1573@aecom.YU.EDU>
Reply-To: kwe@bu-it.bu.edu (Kent England)
Followup-To: comp.dcom.lans
Organization: Boston Univ. Information Tech. Dept.
Lines: 35

In article <1573@aecom.YU.EDU> naftoli@aecom.YU.EDU (Robert N. Berlinger) writes:
>Does a choice of multi-mode or single-mode fiber make a difference 
>as far as FDDI?
I think the emerging FDDI spec allows for several options in selection
of fiber type.
> In not, which is best for a lan (i.e., which 
>will be the most popular, easy to buy hardware for, etc.)?  
I think single mode fiber is impractical for LANs.
Connectorizing single mode fiber requires a portable lab in a truck.
Multimode fiber connectorizing and splicing can now be done out of a
kit by a meticulous technician, such as a broadband tech.
Single mode requires a laser, multimode can use LEDs.
The FDDI ring will be limited to 23 km or less.  This is very
practical for multimode and large campuses.  Single mode not required.
AT&T seems to be dominating the multimode arena.  They go with 62.5
micron fiber.  I would recommend that diameter.  Then your fiber could
also be used for telephone multiplexers.
A big design decision is star vs ring.  FDDI is logical ring, but you
can install it physically as a star or ring.  Design for expansion and
know the FDDI limits, which I think are 23 km.  [Correct me, but don't
flame me, please.]
I haven't yet decided whether to stay with AT&T standard SMA
connectors or use ST connectors.  The screw on SMAs are very difficult
to patch and repatch.  Perhaps the mini bayonet STs are better.  Comment?
Boston University has installed a 62.5 u physical ring running Pronet
80.  We connectorize and maintain the network ourselves.
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