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.