OSPF Weight Setting Optimization for Single Link Failures

Abstract: In operational networks, nodes are connected via multiple links for load sharing and redundancy. This is done to make sure that a failure of a link does not disconnect or isolate some parts of the network. However, link failures have an effect on routing, as the routers find alternate paths for the traffic originally flowing through the link which has failed. This effect is severe in case of failure of a critical link in the network, such as backbone links or the links carrying higher traffic loads. When routing is done using the Open Shortest Path First (OSPF) routing protocol, the original weight selection for the normal state topology may not be as efficient for the failure state. In this paper, we investigate the single link failure issue with an objective to find a weight setting which results in efficient routing in normal and failure states. We engineer Tabu Search Iterative heuristic using two different implementation strategies to solve the OSPF weight setting problem for link failure scenarios. We evaluate these heuristics and show through experimental results that both heuristics efficiently handle weight setting for the failure state. A comparison of both strategies is also presented.