Cross-over spanning trees Enhancing metro ethernet resilience and load balancing

The economics and familiarity of Ethernet technology is motivating the vision of wide-scale adoption of Metro Ethernet Networks (MEN). Despite the progress made by the community on additional Ethernet standardization and commercialization of the first generation of MEN, the fundamental technology does not meet the expectations that carriers have traditionally held in terms of network resiliency and load management. These two important features of MEN have been addressed in this paper. We propose a new concept of Cross-Over Spanning Trees (COST) that increases the resiliency of the MEN while provisioning the support for load balancing. As a result, the capacity in terms of network throughput is greatly enhanced while almost avoiding any re-convergence time in the case of failures. The gain ranges from 1.69% to 7.3% of the total traffic in the face of failure; while load balancing increases an additional 12.76% to 37% of the total throughput.