Hi Paul, Thanks. I scored a copy of GR-253 and think I found the relevant sections. Not surprisingly, there two requirements:
* switch initiation time (ie time to detect that a switch is to be performed) * switch completion time. The detection time is required to be capped at 10 ms and the switch completion time is the infamous 50ms time. So it appears that data being transported over SONET might observe upwards of 60 ms of interruption... Of course, this is supposed to be worst case. Interestingly, there's reference to another document which looks like it might provide some rationale for some of the design aspects to SONET: TR-NWT-000418 "Generic Reliability Assurance Requiremetns for Fiber Optic Transport Systems". Yawn. Guess this one is the next step... Paul Burke wrote: > > You may want to get a hold of the Bellcore GR 253 > SONET generic standards doc or other SONET Bellcore GR > docs relating to switching times and the equivalent > SDH ITU-T standards (which I am not sure what it is). > On the SDH side you may want to start with ITU-T > G.783. > > Hope this helps > > pb > > > --- bergenpeak wrote: > > Sorry for the OT post. Figured I'd float this here > > and see if > > any one might be able to help. > > > > Does anyone really know where the 50 ms SONET > > detect/fail-over time > > comes from? > > I've heard many answers, but none seem to be > > verifiable. I'm looking > > for pointers to docs which explain where or what > > drove the 50 ms number. > > > > I've heard that: > > > > * 50 ms was a requirement to support voice. The > > way this one is told > > is that > > more than 50 ms of noise/nothingness seriously > > impacts MOS. Not sure > > I buy that. > > > > > > * Old telco switches would go bonkers if many T1's > > started to flap > > a the same time. 50ms at the SONET level > > prevented the T1s from > > flapping. > > > > * others, etc. > > > > Again, looking for docs / pointers which details the > > answer. > > > > Thanks > [EMAIL PROTECTED] > > __________________________________________________ > Do you Yahoo!? > Faith Hill - Exclusive Performances, Videos & More > http://faith.yahoo.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=55948&t=55700 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
