At 7:00 -0800 1/16/97, Howard C. Berkowitz wrote:
I can't claim to have recent numbers that suggest otherwise, but, some historical information might at least be interesting. In the early 80s, I did a good deal of X.25 capacity planning. At what was then GTE Telenet, we found that up to 50% of our traffic stayed local in large cities. The larger the city, the more that seemed to stay local...this was especially obvious in New York, where a great deal of financial data flowed.
remember that in the early 80's you basically couldn't lease a T1 from AT&T (I think it was 82 or so when they were first tariffed?) (watch out for that DC voltage...ouch! :-). also DDS services were scarce, etc. So (expensive) low speed analog was the option for leased lines - and private networks were rare. Since then of course the fallout from Judge Greene has changed some things, and it is cheap and easy to put up a DS0 across town - the cost justification vs. per packet charges is a lot different.
Now, these old statistics reflect mainframe-centric traffic, and more private-to-private than arbitrary public access. The latter is much more characteristic of Internet traffic.
SNA and X.25 tended to emphasize the ability to fine tune access to a limited number of well-known resources, with relatively well-understood traffic patterns. The Internet, however, has emphasized arbitrary and flexible connectivity, possibly to the detriment of performance tuning and reliability.
well the strategies for performance tuning are certainly different. [stuff cut]
Web cacheing would seem to encourage traffic to stay local.
ahhh....yup. dave