1) do a traceroute from A to B, number of hops reported = n
2) send a ping from A to B and look at the ttl field, most os's start ttl at
64 or 255 (easy to figure out which). Subtract from ttl value.
3) now take the difference of these two numbers. If the difference is large
then there are alot more hops in one direction than the other. I've found a
couple doozies, but generally folks are pretty close. It'd be a one day
project for someone to built a random tester to measure this though.
- Stefan