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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: SONET ring questions
At 10:42 AM 10/19/98 -0500, Dave Cooper wrote: >At 10:36 PM 10/16/98 +0100, Manar Hussain wrote: >> >>>How many significant digits do you consider acceptable? Even in an ideal >>>APS environment, link failure detection and protection switching does take >>>finite time. You might get 99.999% uptime, but probably not 99.9999999%. >> >>The thing that always got me was that there never seems to be a mention of >>the sampling period for the stat. >> >>>Methinks that you've been subjected to Marketing. ;-) >> >>Well ... I'll give you 99.9999999% on any system you like - with a sampling >>period of say every billion years. I think that allows me to stay down for >>the first 100 years, long enough to extend beyong the life of any stressed >>sysadmin :) >> >>More seriously - SLA's that specify a sampling period then also give an >>indication what is considered too long an outage. If you get just under the >>.1% downtime allowed per year all in one go you may well be pretty pissed >>at being told the 8 hour outage was within the SLA. > >The quasi Engineering guidelines for many CLECs when calculating average >downtime over a year's span is 52 minutes (meaning .0001% downtime over >the year). Anything above and beyond this estimate would be suspect. Sorry, drop the % on the .0001 -> should be .01%. Coffee wasn't strong enough this morning. Thanks Barry. -dave cooper eli >Obviously, these Engineering baselines vary from carrier to carrier. >Also, this 52 minute guideline relates to the SONET ring and the muxes >and not the tributaries (OC-3 or OC-12) or the optical/electrical hand-offs >that might fail due to bad terminations/bad wiring/or misconfigured nodes. >A common failure for OC-3c or OC-12c is the 2-fiber optical handoff to the >customer which has nothing to do with the SONET ring itself or the associated >SONET gear. >Dave Cooper >Electric Lightwave, Inc. >Disclaimer: Comments above reflect my experience with numerous CLECs and >not specifically ELI. > > >> >>Manar >> >
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