My analysis was assumed to apply within a single service providers
backbone. I believe you can report end-to-end availability within a single
service provider's backbone and have a meaningful number. But leased lines
bring that figure down into the range of 99.7%. I think frame relay has the
promise of getting that up to .8 or .85, if the regional bells get good at
FR net mgmt.
The dismal situation you are referring to is the 12-15 service provider
backbones, all mashing together at 7-8 exchange points with lots of paths
that wind back and forth over asymmetric routes from one coast to the other
and back.
It's a lot different than when NSFnet was the default. No more default.
Today routing is more complex, business is lower margin, and engineer folks
don't have time to look up from their router memory overload and route
cache woes to figure out why their routes thru ISP#17 aren't optimal.
--Kent