A Non-Weighted Load Balanced Fast Local Protection Scheme for IP Networks

In this paper, we propose a non-weighted load balanced fast local protection scheme for survivable IP networks. Unlike conventional shortest path based routing, we relax shortest path constraints in computing working and backup routes to achieve load balancing purposes. Once a failure occurs, those nodes adjacent to the failure point use their backup routing tables to achieve fast local failure recovery. Only the affected traffic is diverted to bypass a failure. The approach adopts failure set concept such that the proposed scheme can be used to handle various kinds of scenarios including single link, single node or even shared risk link group (SRLG) failure. We formulate this problem as a mixed integer linear programming (MILP) to minimize the traffic load on the most congested link. Since this problem is not tractable by its NP-hard property, we further decompose it into several sub-problems. Each sub-problem is solved optimally and the original problem is approximated by combining the solutions of those sub-problems. We perform experiments on benchmark networks and compare the proposed scheme to well-known schemes on survivability, path lengths and link load distribution for normal and rerouted states. Through numerical results and comparisons, we delineate that the proposed approach achieves a sub-optimal solution, which is profoundly to its high survivability and load balancing at the expense of slightly longer average path hop count.