I am curious to know what you think is "correct" instrumentation. Clearly in simple cases, capacity planing can be done with link statistics. But it is not possible to compare the effective (useful?) capacities of two different topologies without some form of traffic matrix. I have observed real situations where "better" topologies turned out to be worse, due to unanticipated large traffic streams between sites. Even a simple task, like inserting a bridge to raise the performance of an overloaded ethernet quickly degenerates into an exercises in combinatorics unless guided by a mac layer traffic matrix. I take it as a given that the Internet needs pro-active topology management encompassing the upper level ISP's and interconnects. Given that, what statistics and procedures would you suggest? --MM-- P.S. I understand that there are business reasons for customers to want to hide their traffic. However, a full 20k route by 20k route traffic matrix is about 2 GB per sample interval, which is pretty hard to inhale. The best possible data collection must be pretty sparse, due to CIDR or other aggregation, coarse time scales and limited visibility. This really seems like the hard way to snoop somebody else's business. Unless you are aware of examples..... --MM--