An optimization framework for load balancing in metro Ethernet networks

In Ethernet, the basic protocol that creates a loop free topology is IEEE Spanning Tree Protocol (STP). STP suffers from poor load balancing because all customers use the same spanning tree. As a solution to this problem, the IEEE 802 working group has introduced Multiple Spanning Tree Protocol (MSTP) that allows a switch to participate in multiple spanning trees. However, the MSTP standard does not define how the spanning trees should be created and how the traffic flows should be assigned to the spanning trees. In this paper, we propose an optimization framework for selecting the best spanning trees to improve the load balancing and resources utilization. By using this approach, the traffic load can be balanced across links and switches. We show the performance of our approach through some simulations on a simple network topology.