Throughput Guaranteed Restorable Routing Without Traffic Prediction

Two-phase routing, where traffic is first distributed to intermediate nodes before being routed to the final destination, has been recently proposed for handling widely fluctuating traffic without the need to adapt network routing to changing traffic. Pre-configuring the network in a traffic independent manner using two-phase routing simplifies network operation considerably. In this paper, we extend this routing scheme by providing resiliency against link failures through two different fast restoration mechanisms - local (link/span) based and end-to-end (path) based. We view this as important progress towards adding carrier-class reliability to the robustness of the scheme so as to facilitate its future deployment in Internet service provider (ISP) networks. The main contribution of the paper is the development of fast combinatorial algorithms for routing under the scheme with link and path restoration mechanisms so as to minimize the maximum utilization of any link in the network, or equivalently, maximize the throughput. The algorithms developed are fully polynomial time approximation schemes (FPTAS) - for any given epsi > 0, an FPTAS guarantees a solution that is within a (1 + epsi) -factor of the optimum and runs in time polynomial in the input size and 1/epsi. To the best of our knowledge, this is the first work in the literature that considers making the scheme resilient to link failures through pre-provisioned fast restoration mechanisms. We evaluate the performance of link and path restoration (in terms of throughput) and compare it with that of unprotected routing. For our experiments, we use actual ISP network topologies collected for the Rocketfuel project.