Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!unmvax!ncar!boulder!bobk
From: bobk@boulder.Colorado.EDU (Bob Kinne)
Newsgroups: comp.dcom.lans
Subject: Re: Request For Opinions: FDDI follow-up
Message-ID: <8137@boulder.Colorado.EDU>
Date: 14 Apr 89 18:54:31 GMT
References: <4824@charon.unm.edu> <29505@bu-cs.BU.EDU> <1507@Portia.Stanford.EDU> <825@oregon.uoregon.edu> <29548@bu-cs.BU.EDU>
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Reply-To: bobk@boulder.Colorado.EDU (Bob Kinne)
Organization: University of Colorado, Boulder
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In article <29548@bu-cs.BU.EDU> kwe@buit13.bu.edu (Kent England) writes:
>	With the dual counter-rotating ring you have the secondary
>ring in standby in case of node failure.  If a node on the ring fails,
>then the adjacent nodes "wrap" and use the primary and secondary paths
>to create a new ring that bypasses the failed node.
>
>	Why do you want optical bypass fault tolerance as well?

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.  In some
architectures the bypass may be initiated remotely from a ring
master in the event the node fails in a manner that disrupts the
network.