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- 08-15-2003, 11:03 PM #1danny bursteinGuest
In <[email protected]> Steve & Susan <moc.enilepip@ykkams> writes:
>On Fri, 15 Aug 2003 06:01:30 -0700, Group Special Mobile
><look@signature_to.reply> wrote:
>>No system whether it's land lines or mobile phones is engineered for
>>disasters
>You mean no post-cold war, post-deregulation system is engineered for
>disasters. Old wireline "Bell System" infrastructure was absolutely
>engineered for disasters. They were a vital partner in our nation's
>homeland security in the 50's, 60's and 70's.
Not quite as easy as that. While the phone equipment and network in the
days of One Bell System, It Works, would last through just about anything
imaginable, the network was NOT designed to be non-blocking.
In other words, a typical telco switch would only allow, say, 5 percent of
the subscribers to be on the phone at any one time. And calls between
central offices required trunks which were similarly limited.
There's a very detailed science in making these designs - trying to figure
out what capacity a switch needs. Check out "erlang".
--
_____________________________________________________
Knowledge may be power, but communications is the key
[email protected]
[to foil spammers, my address has been double rot-13 encoded]
› See More: telco resorces, was: NY Blackout and Cell Usage
- 08-16-2003, 10:21 AM #2Steve & SusanGuest
Re: telco resorces, was: Re: NY Blackout and Cell Usage
On Sat, 16 Aug 2003 05:03:32 +0000 (UTC), danny burstein
<[email protected]> wrote (after I said):
>>Old wireline "Bell System" infrastructure was absolutely
>>engineered for disasters. They were a vital partner in our nation's
>>homeland security in the 50's, 60's and 70's.
>
>Not quite as easy as that. While the phone equipment and network in the
>days of One Bell System, It Works, would last through just about anything
>imaginable,
I thought that's what I said. In fact, there are great pictures and
descriptions of old (and now defunct) AT&T Long Lines facilities all
over the web - complete with nuclear blast detectors and electric
combustion toilets. They just don't make those anymore. I'm still
looking for a good 220 Volt toilet for my garage.
>the network was NOT designed to be non-blocking.
I didn't say that.
But, anyway, the network now holds some of that capacity in abeyance
for continuity of government. Pretty important because what emergency
manager can compete with everyone calling home to tell someone to turn
their TV on (oh, wait, there was no TV)?
>There's a very detailed science in making these designs - trying to figure
>out what capacity a switch needs. Check out "erlang".
Erlang B is a fine algorithm as a STARTING POINT. Empirically, other
factors are important in considering how many trunk groups are
actually needed. For instance, (a real-life situation in E 9-1-1
infrastructure) is it wise for an ILEC in a given area to concentrate
250 square miles containing one small city and diverse rural areas,
each with with its own uniquely identifiable center of community, into
only three trunks given simply following Erlang B?
Steve
- 08-20-2003, 10:53 PM #3David SGuest
Re: telco resorces, was: Re: NY Blackout and Cell Usage
On Sat, 16 Aug 2003 11:21:42 -0500, Steve & Susan <moc.enilepip@ykkams>
chose to add this to the great equation of life, the universe, and
everything:
>I thought that's what I said. In fact, there are great pictures and
>descriptions of old (and now defunct) AT&T Long Lines facilities all
>over the web - complete with nuclear blast detectors and electric
>combustion toilets. They just don't make those anymore. I'm still
>looking for a good 220 Volt toilet for my garage.
I visited one of those places in high school (ca. 1982). On the surface
there were a few shacks, but you went into one and down the stairs and it
was a HUGE complex. They said it was designed to withstand 1 megaton at 1
mile, except that they never installed the blast doors on the ventilation
system (or something like that). There were rows of HUGE lead-acid
batteries (I remember them as about 4 feet high, but I may be wrong) with
HUGE busses running across the tops (I thought they compared to the floor
joists in my house), which the guide said were connected directly in
parallel with the power supply so that A: they would get a constant trickle
charge; and B: there would be no switching delay when the power went out.
And their only purpose was to keep the center up for the 110 seconds it
took for the generator to get up to speed (actual battery capacity was
measured in minutes or hours). They had fuel storage to run it for a
certain number of days (60?), but normally only kept about 1/2 or 1/3 that
much on hand. The longest the generator had ever run was (IIRC) 82 or 84
days (longer than the fuel capacity, so they'd had to get at least one
delivery) due to some problem with Com Ed.
They were just starting to experiment with fiber optics. I think they had
*1* guy who was allowed to touch the fiber.
David Streeter, "an internet god" -- Dave Barry
--
http://home.att.net/~dwstreeter
Expect a train on ANY track at ANY time.
"Tourist: Who are you people?
Striking screenwriter: We're writers.
Tourist: What are you striking for?
Writer: More money.
Tourist: How much do you earn?
Writer: $350,000."
- as reported by Bernard Weintraub, New York 'Times'
- 09-08-2003, 04:00 PM #4danny bursteinGuest
telco resorces, was: Re: NY Blackout and Cell Usage
In <[email protected]> Steve & Susan <moc.enilepip@ykkams> writes:
>On Fri, 15 Aug 2003 06:01:30 -0700, Group Special Mobile
><look@signature_to.reply> wrote:
>>No system whether it's land lines or mobile phones is engineered for
>>disasters
>You mean no post-cold war, post-deregulation system is engineered for
>disasters. Old wireline "Bell System" infrastructure was absolutely
>engineered for disasters. They were a vital partner in our nation's
>homeland security in the 50's, 60's and 70's.
Not quite as easy as that. While the phone equipment and network in the
days of One Bell System, It Works, would last through just about anything
imaginable, the network was NOT designed to be non-blocking.
In other words, a typical telco switch would only allow, say, 5 percent of
the subscribers to be on the phone at any one time. And calls between
central offices required trunks which were similarly limited.
There's a very detailed science in making these designs - trying to figure
out what capacity a switch needs. Check out "erlang".
--
_____________________________________________________
Knowledge may be power, but communications is the key
[email protected]
[to foil spammers, my address has been double rot-13 encoded]
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