5 9s can be measured all sorts of ways... Network wide, it probably isn't even a blip. Even in terms of all of California service its probably not much more than a blip. Vicky Rode wrote:
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I wonder what ever happened to redundancy? I guess 5 9s (dunno what the going number is) got blown out of the water for them.
regards, /virendra
David Lesher wrote:
Speaking on Deep Background, the Press Secretary whispered:
I'm not completely familiar with the telco jargon. Does Tandem mean the same as a local central office, where POTS lines terminate at the switch? Long Beach has a population of 470,000. The C/Os I know of are:
A "Central Office" switch talks to subscribers aka end-users. On its backside, it talks to other CO's and tandems. Time was, that was also VF copper pairs, but it's long since all DS1 and up.....
A tandem is a switch that talks not to subs, but only to CO's. In days of old, when a {dialup} call went to the other side of town, chances are it went you-yourCO-downtown tandem-joesCO-joe. {copper all the way...}.
A tandem was always housed in large CO building, but might have been ATT's vice the operationg company, etc...
But ESS's and ""classless switching"" and massive expansion of the plant really muddled the picture. An ESS could be both a CO switch [for multiple prefixes and even multiple NPA's..] AND act like a tandem.. And oh, the actual "line cards" can be remoted 100 miles away in a horz. phonebooth box alongside the road in Smallville.... with DS1's/OC coming back.
My guess is a DACS, a cross-connect point that is an software-driven patch panel, lost its marbles. [engineering term of art.....] A DACS could have dozen->MANY dozen DS1/DS3/OC-n going hither and yon. Some will be leased circuits. Others will be the CO trunks going from one switch to another. It may/may not have muxes internal, so that what arrives on a DS1 leaves in a OC96..
I note it went down at 2:20 AM. That SCREAMS software upgrade/cutover. What's to bet GEE, no...VZEEE, was doing just that and there was a major ohshit.
Sean noted a long while back that somehow, DACS crashes always seem to take hours to recover. Maybe the backups are on Kansas City standard tapes, I donno.. but this sounds like that..
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