Improving Load Balance and Resilience of Ethernet Carrier Networks with IEEE 802.1S Multiple Spanning Tree Protocol

In this paper, we address the problem of how to use the IEEE 802.1S Multiple Spanning Tree Protocol (MSTP) to improve load balance and resilience of Ethernet carrier networks. We address the single region MSTP case. First, this protocol enables the network operator to define different Spanning Tree instances and assign without constraints each VLAN to any Spanning Tree, which enables better network load balancing. Second, in the case of a link failure, the Spanning Trees not including the failed link do not need to be reconfigured and, therefore, failure recovery has no impact on their assigned VLANs. We propose a solving technique to determine the MSTP parameters configuration that optimizes load balancing and minimizes the impact of network failures. The computational results show that near optimal results can be obtained with only a small number of Spanning Tree instances.