Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!bloom-beacon!husc6!bu-cs!kwe
From: kwe@bu-cs.BU.EDU (kwe@bu-it.bu.edu (Kent W. England))
Newsgroups: comp.dcom.lans
Subject: Re: FDDI follow-up
Message-ID: <29619@bu-cs.BU.EDU>
Date: 14 Apr 89 20:23:19 GMT
References: <4824@charon.unm.edu> <29505@bu-cs.BU.EDU> <1507@Portia.Stanford.EDU> <825@oregon.uoregon.edu> <29548@bu-cs.BU.EDU> <8137@boulder.Colorado.EDU>
Reply-To: kwe@buit13.bu.edu (Kent England)
Followup-To: comp.dcom.lans
Organization: Boston U. Information Technology
Lines: 20

In article <8137@boulder.Colorado.EDU> 
bobk@boulder.Colorado.EDU (Bob Kinne) writes:
>
>The purpose of the dual ring is to recover from a cut or damaged
>connection between nodes.  If a node fails or powers down, the
>optical bypass permits the ring to continue to function in normal,
>non-wrap mode, bypassing the failed or removed station.  Any ring
>architecture needs to provide this bypass functionality.  

	I don't think it does.  If a node fails, as opposed to a link,
then the adjacent nodes wrap and the ring continues without the failed
node.

	I guess I am just not convinced that optical bypass buys you
that much.  I think the hundreds and hundreds of workstations are
going to be put on single ring FDDIs using star concentrators with
bypass capability (not optical I think).  These concentrators will be
on the dual ring backbone.
	But that's enough on that.  Just let me be in my own misguided
world.  I'll learn the truth soon enough.