One can certainly make the argument that running large traffic flows through shared interconnects is bad engineering
Yes, and I think the operative word is "shared" as in "shared access media".
Shared access to the media is not relevant. Scalability of the shared media is. Private interconnects are simply more scalable than shared interconnects.
It makes sound engineering sense that networks pushing heavy amounts of traffic between each other would like to distribute that load around their networks, rather than try to take it all at the public interconnects. The private interconnects are not necessarily modeled after the public exchange points, but are really ds3 or higher speed circuits positioned between NSP POPs in areas were both networks have good connectivity. If NSPs continue to build out their Networks to support the public NAPs, they would have to deal with higher and higher amounts of concentrated traffic in those areas. With private connects, NSPs can distribute their load in less congested areas of their network. Darin -- \//// ( o o ) ====================================oOO-(.)-OOo========================== Darin Wayrynen, VP of Technology, (602) 303-9500 ext 3234, darin@good.net