A Distributed Scheme for Responsive Network Engineering

Optimal bandwidth utilisation together with resilience and recovery from failure are two key drivers for traffic engineering (TE) which have been widely addressed by the IP community. Most current IGP routing protocols deployed in the Internet and the extensions proposed to adapt these protocols for TE are concerned either with optimality or with resilience. This leads to a duplication of routing protocols and algorithms where each of these objectives (optimality, resilience) is addressed by its own protocol or algorithm. The interactions among these protocols introduce additional complexities which do not necessarily translate into equivalent performance gains. This paper aims at the integration of these two objectives into a unified network resource controller. At random time instants the NRC computes bandwidth prices which are used in an automated scheme to dynamically adjust the bandwidths of the network paths in response to the traffic and network equipment conditions. The distinguishing features of the NRC are that it works without centralised control and thus scales to large networks, and that rather than using TE to move network flows to where the network bandwidth is located, the NRC uses network engineering (NE) to move network bandwidth to where the network flows are located. We next present an efficient heuristic to find diversely routed backup paths and to provision the network links with the least amount of backup (spare) bandwidth in order to be able to deploy equivalent recovery paths for any failure scenario which leaves the network connected. Simulation results are presented which show that the reallocation scheme provides prompt bandwidth provisioning both for random traffic fluctuations during normal operating conditions, and when provisioning recovery routes in the event of network failure.