D2R: Policy-Compliant Fast Reroute

Abstract

In networks today, the data plane handles forwarding - - sending a packet to the next device in the path - -and the control plane handles routing - -deciding the path of the packet in the network. This architecture has limitations. First, when link failures occur, the data plane has to wait for the control plane to install new routes, and packet losses can occur due to delayed routing convergence or central controller latencies. Second, policy-compliance is not guaranteed without sophisticated configuration synthesis or controller intervention. Fast reroute mechanisms in the data plane cannot provide both connectivity and policy-compliance guarantees. We take advantage of the recent advances in fast programmable switches to perform policy-compliant route computations entirely in the data plane, thus providing fast and programmable reactions to failures. D2R provides the illusion of a hierarchical network fabric that is always available and policy-compliant under failures. We implement our data plane in P4 and show its viability in real world topologies.