Subject: Network controls RE: [Ieprep] RE: PSTN collapse

From: "Gunn, Janet" <[email-masked]>
Date: Tue, 17 Dec 2002 10:33:18 -0500

The PSTN  has a wide variety of network controls that can be activated,
depending on the exact nature of the situation.

These include 
Blocking all calls OUT of the area  identified
Blocking all calls INTO the destination identified
Regulating the rate at which calls are submitted to a destination.

And a bunch of others.

The choice of which to activate varies on a case by case basis, based not
just on the traffic itself, but on the external cause.  For instance, in a
natural emergency, you may want people in the area to be able to make "I'm
OK" outbound calls (while blocking incoming calls), but in the case of
something like the Oklahoma City bombing, you might block both incoming and
outgoing calls, to make resources available for communication within the
area.

One of the things that GETS does is to provide exemption form these
controls.

But it is NOT an indication of the PSTN "collapsing"- it is an indication of
the PSTN adapting to prevent collapse. (If you didn't do it, you could end
up with lots of resources being wasted trying to set up calls which could
not complete, blocking the calls which COULD complete.)

-----Original Message-----
From: Dave Crocker [mailto:[email-masked]]
Sent: Monday, December 16, 2002 6:36 PM
To: RJ Atkinson
Cc: [email-masked]
Subject: Re: [Ieprep] RE: PSTN collapse

RJ,

Monday, December 16, 2002, 11:02:57 AM, you wrote:
RJ> Such shutdowns are normally performed on inbound calls from outside
...
RJ> Of course, I don't know what was in your presentation, so can't say
RJ> whether I'd agree with the phone company assertions or not.

The anecdote was about outbound calls, but the nature of GETS makes it
pretty clear that a sufficient emergency will close the system in both
directions, except for 'authorized' users.

FYI, the anecdote was about Van Jacobsen being at Stanford when the quake
hit, and immediately wanting to contact his girlfriend, back in Berkeley.
He tried to call, but of course that did not work.

Out of frustration, he sent her some email, though I am told he only did
that for the sake of having something to do.  However, he got a response
from her within a relatively short time.

He was astonished that things were working that well, so he did a traceroute
to find the path.

Sure enough, the Internet path from Stanford to Berekely went down to L.A.,
across the U.S. and then back across to Berekely.

Or, at least, that is the way I heard the story.

d/
-- 
 Dave <mailto:[email-masked]>
 Brandenburg InternetWorking <http://www.brandenburg.com>
 t +1.408.246.8253; f +1.408.850.1850

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