Behaviour of Maximum-Throughput Dynamic Routing in Loopy Networks⋆

Maximizing network throughput via back-pressure routing is the subject of a considerable body of literature. However, the associated optimal throughput guarantees come at the cost of excessively high delays. Though there exists some proposals in literature for improving the delay performance, the impact of these proposals on the delay performance is very little in loopy networks (i.e., networks with routing loops). In this demonstration, with series of experiments over different topologies, we show that the basic back-pressure algorithm and two of its variants for improving delay performance induce extensive routing loops with associated high packet delay even in simple network topologies.