Routing policies play an essential role in how traffic is forwarded across the Internet. The network would not be commercially viable without these routing policies, but policies also introduce inefficiencies and fail to fully exploit the underlying network topology. Our work assumes routes are selected according to some policy such as a valley-free routing policy. However, we apply policy at an aggregate traffic level and don't require individual packets to follow paths that match the policy.

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... ur approach never reduces, and usually increases, the connectivity and capacity of the network, and does not infringe on the underlying motivations that led to the routing policy. By adopting this approach, we also provide polynomial algorithms for otherwise NP-hard problems, including finding maximum policy-observing routing capacity between two sets of AS's, minimumizing cuts separating all policy-observing paths between two sets of AS's, and maximumizing sets of edge-or vertex-disjoint policy-observing paths.