North American Network Operators Group
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Re: Vulnerbilities of Interconnection

  • From: Sean Donelan
  • Date: Thu Sep 12 23:21:07 2002 
On Thu, 12 Sep 2002, John M. Brown wrote:
> I guess the question is.
>
> At what point does one build redundancy into the network.
>
> I suspect its a balancing act between reducancy, survival (network)
> and costs vs revenues.

In 1982 AT&T was still a monopoly, could spend whatever it took and the
primary threat was missles from the Soviet Union.  AT&T had ten Class 1
Regional Centers in the country.  Regional Centers were the "top" of the
telephone network routing hierarchy fully connected to other regional
centers.

http://www.rand.org/publications/RM/RM3097/RM3097.appb.html

I don't know how AT&T came to the conclusion that 10 was the perfect
compromise between cost, reliability and survivability.  They had
lots of smart people who knew networks working on the problem, so
I'm assuming they had a decent justification to back up the choice.