Subject: [Ieprep] PSTN collapse

From: "Ayyasamy, Senthilkumar (UMKC-Student)" <[email-masked]>
Date: Mon, 9 Dec 2002 14:59:04 -0600

>       On Mon, 9 Dec 2002 [email-masked] wrote:
>     > I don't consider inability to get dial tone as "collapsed".

No Dial tone = No connection (PSTN) 
Welcome to the world of SIP, where you get dial tone but still
remain disconnected. This is due to the interesting concept of 
separation of session establishment and resource reservation in
SIP based systems. If for some reason the resource reservation 
fails, the call will be set up even though network doesnt support.
So, your phone may be ringing even though the network cannot
support the call. It was one of the problems discussed during
initial days of SIP. But, there are many proposed fixes to avoid 
the above situation. 

>     > Can someone give an example of when and where "the PSTN 
> collapsed"
>     > during an emergency?

Please go through all the trade press articles about 9/11.
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From: "Ayyasamy, Senthilkumar (UMKC-Student)" <[email-masked]>
Date: Mon, 9 Dec 2002 16:57:23 -0600

>>> collapsed" during an emergency? 

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

I am aware of only RFC 896, which talks about congestive collapse
and how it leads to "Internet meltdown". 

Please provide reference to PSTN collapse (since i dont have any
access to ITU-T documents.) If local meltdown is not collapse,
then what is your definition of PSTN collapse? 

The _only_ good part of PSTN is to determine malicious calls.
call trace and tapping issue, which i think(?), is not dealt in
IP telephony.

PS: Mike, can you try not to sent htmlized mails.
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From: [email-masked]
Date: Tue, 10 Dec 2002 10:19:54 EST

In a message dated 12/9/2002 6:30:52 PM Eastern Standard Time, 
[email-masked] writes:

Mike,

    [RJA] You are seriously inconsistent with yourself.  Access links are 
entirely
comparable to "wires to your house" -- because those are common kinds of 
access
links.  Yet, you are totally worked up about IP congestion on access links 
even
though most access links only have one site (e.g. house in the case of DSL)
behind the link.  If local outages don't count for the PSTN, then it is only
fair, reasonable, and logical that they don't count against the Internet.

[MAP] Yes, I understand that is one case, "access" links are like phone wires 
coming into my house. "Local outages" count in both cases, but that again is 
not the real issue here, rather congestion is. In the PSTN, congestion is 
dealt with on my phone wire since only 1 call can be made at a time. The CO 
won't connect a second call to my line when one is there, thus not causing 
the existing call to become of such poor quality that I can't talk. And for 
the emergency case, whether it is a 911 call or an authorized GETS user, they 
can use the line by disconnecting the current call or telling the other 
person to get off the line (with penalties for not giving it up). In the 
Internet case, it has been clealy identified that in the case of a local 
access line (into my house or serving a group of end users) that this is not 
true. Many distant users, can establish sessions (SIP) to devices at my end 
of that "access" link and nothing stops them from all trying to send media 
until all of them have such degraded quality that none of them can talk. The 
whole point here has been to find a solution to this "problem".

    [RJA] You also selectively reply to email.  Several folks gave specific 
examples
where access wires were in place, yet dial tone did not exist for long periods
of time (e.g. Bill Woodcock's Loma Prieta example, among several posted here
recently).  You seem to have a kind of selective amnesia to facts that you
find inconvenient.

[MAP] I was not aware that there was a question related to the above. Of 
course there are many cases in which access wires are in place and no dial 
tone for long periods. No one has diputed that. And I freely admit that there 
have been some massive failues in the PSTN caused, for example, by a Central 
Offic burning. (I just don't think "PSTN collapse" is the right way to 
describe such an event.) I don't know what the point of the above quite wa or 
the question was.

    [RJA] Your hypocritical behaviour is impressively bad -- accusing others 
of
not providing a direct response while you fail to acknowledge that numerous
specific PSTN collapse events HAVE been presented here recently -- and
presented by several different folks.

[MAP] I'll let others who read this list judge who is being hypocritcal.

Mike Pierce
Artel

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From: "King, Kimberly S." <[email-masked]>
Date: Mon, 16 Dec 2002 10:00:33 -0500

All,

As a mathematician, I *love* queuing theory and if interested, Kleinrock's
Queuing Systems is a great place to start.  

But...we might be getting in the weeds here.  I'm still in search of a clear
concise problem definition.

Kimberly