Interdomain BGP policies — where traffic should exit a network
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In this series, I’m going to discuss different reasons for these kinds of policies, and different ways to implement them in interdomain BGP. I’ll refer to Figure 1’s reference network throughout this post.
There are many reasons an operator might want to select which neighboring AS to send traffic through, towards a given reachable destination (for instance, 100::/64). Each of these examples assumes the AS in question has learned multiple paths towards 100::/64, one from each peer, and must choose one of the two available paths to forward along.
Assuming AS65006 is an edge operator (commonly called enterprise, but generally just originating and terminating traffic, and never transiting traffic), there are several reasons the operator may prefer one exit point (through an upstream provider), including:
