> > If I peer with network X in cities A and B, and receive the same route in > > both cities with an AS-path of X, how do I know which city to use for an > > exit? I can understand how if X uses communities to tag the geographic > > origin of the traffic, but I'm not aware of many networks that do > > this. Lots of networks claim to use cold-potato routing though, so how do > > they do it? > > they use the MED sent on the route (aka metric) from the > other provider to determine which exit where they both interconnect > is the "shortest". > > this can at times provide undesired results because of > aggregation.
Besides aggregation, wouldn't this lead to a lot of ties? Let's say the cities are LA & Manhattan, and the route from X originates in Chicago. I would think that it would be a common occurrance for the route to have the same metric in LA & Manhattan. -Ralph