Subject: [Ieprep] RE: PSTN collapse

From: "King, Kimberly S." <[email-masked]>
Date: Tue, 10 Dec 2002 05:39:56 -0500

Mike said:
>As usual, I see that you can not answer a direct question regarding a
>wild claim about how bad the PSTN is. 

Mike,

I started this "PSTN collapse" talk when I made the following statement 

"At the crux of the matter, the Internet is not centrally controlled, is
extremely survivable, and was specifically engineered to avoid congestion
collapse so *if* the problem is to avoid congestion collapse in an emergency
(as defined by the way the PSTN collapses in an emergency) then the answer
probably is that the Internet already does that. " 

So, what do I mean by "PSTN collapse"?  I mean that many of the population
in a disaster area cannot get dial tone or receives busy signals.  I am not
assuming physical damage to the lines.  I am assuming that people are
blocked because there aren't enough resources to share.  If this were not a
genuine problem during emergencies, then the U.S. government has spent an
enormous amount of money on a service called GETS that was completely
unneeded.  I assure you they have not created GETS on the whim that maybe
such a problem could occur.  

Note that I *never* said that the PSTN is bad, nor do I believe such a
thing.  We are not here to have an Internet vs. PSTN battle.  Both networks
are good; one happy family!

My point is that this working group needs to create concise problem
statements about exactly what problem(s) they are attempting to solve.  It
is also to examine if the problems encountered are really the same as the
PSTN (e.g., call blocking) or if they have new problems.

Kimberly

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From: Marshall Eubanks <[email-masked]>
Date: Tue, 10 Dec 2002 09:56:58 -0500

When I lived in California we went through two significant (not major) 
earthquakes.
Both times we could not complete an outbound call for some hours - but 
once
we got through, the connection was fine.

That sounds like a PSTN collapse to me.

I heard from a Japanese colleague that the PSTN collapse after the Kobe
earthquake was particularly bad.

Regards
Marshall Eubanks

> PSTN (e.g., call blocking) or if they have new problems.
                                  Regards
                                  Marshall Eubanks

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---

From: Henning Schulzrinne <[email-masked]>
Date: Tue, 10 Dec 2002 10:16:25 -0500

Does anybody have real, numeric data on how much additional Internet 
traffic was generated during these events?

There are really two separate dealing-with-collapse questions here that 
seem to be conflated constantly:

- how well does a system deal with a sudden, unplanned flood of 
additional (emergency-induced) traffic?

- how well does a system cope with partial destruction of the underlying 
infrastructure

At least from what I can tell, except for places like links to CNN, 
overall Internet traffic does not increase significantly during 
emergencies (or has not in the past). CNN.com and similar sites 
obviously did "collapse" until they could be reconfigured (e.g., by 
converting to text-only content). People send more email during 
emergencies, but they probably worry less about ordering books from 
Amazon, exchanging music files or playing networked games.

Thus, unless somebody has verifiable proof that the Internet had, say, 
sustained traffic several times larger than usual during those 
emergencies, these experiences say very little should a significant 
fraction of the existing interactive communications traffic move to the 
Internet. After all, except for downtown, the problem in Manhattan was 
mostly a sudden surge in volume. (Downtown, there was no Internet, 
either...)

A separate question is whether emergencies are likely to induce such 
floods of traffic. However, I think it is more honest to separate these 
issues.

---

From: Marshall Eubanks <[email-masked]>
Date: Tue, 10 Dec 2002 16:55:25 -0500

Henning;

Did you see the NANOG-23 presentations on this ? That is the best start 
I can recommend :

http://www.nanog.org/mtg-0110/agenda.html

(The Monday morning talks -  They are all on line I believe.)

Regards
Marshall Eubanks

On Tuesday, December 10, 2002, at 10:16  AM, Henning Schulzrinne wrote:

> - how well does a system cope with partial destruction of the 
> underlying infrastructure
>

T.M. Eubanks

---

From: Bill Woodcock <[email-masked]>
Date: Tue, 10 Dec 2002 18:46:58 -0800 (PST)

On Tue, 10 Dec 2002, Henning Schulzrinne wrote:
    > emergencies.

Correct.  Traffic does not increase during infrastructure collapse, but
capacity and diversity are typically somewhat reduced.  Rarely to the
point that any actual decreased performance could be observed by a user,
however.

What increases traffic is events like the Mars lander.

                                -Bill

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From: Dave Crocker <[email-masked]>
Date: Sat, 14 Dec 2002 07:57:42 -0800

Marshall,

Tuesday, December 10, 2002, 6:56:58 AM, you wrote:
Marshall> When I lived in California we went through two significant (not major) 
Marshall> earthquakes.
Marshall> Both times we could not complete an outbound call for some hours - but 
Marshall> once
Marshall> we got through, the connection was fine.

Folks,

Marshall> That sounds like a PSTN collapse to me.

I once did a presentation to some telephone company folks and cited the
telephone situation after the 1989 quake, referring to it a the quake's
breaking the phone systems.

They got very upset with me.

In an emergency, the phones are automatically shut down for regular use, to
ensure that there is capacity for the emergency calls.

Such an actions is very much NOT "collapse".

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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From: RJ Atkinson <[email-masked]>
Date: Mon, 16 Dec 2002 14:02:57 -0500

On Saturday, Dec 14, 2002, at 10:57 America/Montreal, Dave Crocker 
> Such an actions is very much NOT "collapse".

Such shutdowns are normally performed on inbound calls from outside
the disaster area, in order to leave more capacity for outbound
calls originating within the disaster area.  So loss of service to
phones in the disaster area that were still connected by good copper 
wires
would constitute a reasonable count for measuring congestion collapse.

Of course, I don't know what was in your presentation, so can't say
whether I'd agree with the phone company assertions or not.

Ran

---

From: Dave Crocker <[email-masked]>
Date: Mon, 16 Dec 2002 15:35:59 -0800

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