[85954] in North American Network Operators' Group
Re: Verizon outage in Southern California?
daemon@ATHENA.MIT.EDU (Deepak Jain)
Wed Oct 19 16:17:49 2005
Date: Wed, 19 Oct 2005 16:16:00 -0400
From: Deepak Jain <deepak@ai.net>
Reply-To: deepak@ai.net
To: vickyr@socal.rr.com
Cc: wb8foz@nrk.com, nanog list <nanog@merit.edu>
In-Reply-To: <43568257.2030208@socal.rr.com>
Errors-To: owner-nanog@merit.edu
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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