Selecting the Best Spanning Tree in Metro Ethernet Networks using Genetic Algorithm

IEEE Spanning Tree Protocol (STP) is a layer-2 protocol which ensures a loop free topology in Metro Ethernet networks. It is based on Minimum Spanning Tree solution that involves determining the links which can join all the nodes of a network together such that the sum of the costs of the chosen links is minimized. In STP, all customers need to use the same spanning tree and there isn’t any traffic engineering mechanism for load balancing. This results in uneven load distribution and bottlenecks, especially close to the root. A solution for this problem is using the multi-criteria Minimum Spanning Tree by considering criterions such as load balance over links and switches. In our previous work, the algorithm was based on computation of the total cost for each possible spanning tree and then selection the best one with minimum total cost. This algorithm is very time consuming, especially when our Metro Ethernet network is large. In this paper, we propose a new approach using Genetic Algorithm. It reduces the computational complexity by selecting the best spanning tree in a stochastic manner.