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