Routing and capacity assignment in backbone communication networks under time varying traffic conditions

This paper studies the problem of assigning capacities to links in a backbone communication network and determining the routes used by messages for all communicating node pairs in the network under time varying traffic conditions. The best routes are to be chosen from among all possible routes in the network. Tradeoffs between link costs and response time to users are achieved by specifying an upper limit on the average link queueing delay in the network. The goal is to minimise total link fixed and variable costs. The topology of the network and the end-to-end traffic requirements during the different busy-hours are assumed to be known. The problem is formulated as a mathematical programming model. An efficient solution procedure based on a Lagrangian relaxation of the problem is developed. The results of extensive computational experiments across a variety of networks are reported. These results indicate that the solution procedure is effective for a wide range of traffic loads and cost structures.