Well, I'm no theoretical mathematician, but I think your problem is going to involve compromise on some level. In fact, for even three nodes, it's possible that the "link distance" is insolvable, if the ping times between A and B exceed the sum of the ping times from A to C and C to B. So whatever algorithm you choose, it's going to involve some sort of first order approximation, and a satisfaction threshold, rather than some rigid math. Maybe that will help decide how to do it.

-- Randal L. Schwartz, Perl hacker