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Re: Verizon outage in Southern California?

  • From: Vicky Rode
  • Date: Wed Oct 19 13:30:23 2005

Hash: SHA1

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.


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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