A Simulation Study of GELS for Ethernet Over WAN

Ethernet is a low-cost, flexible and high-speed transport technology, which has traditionally seen success in local area networks and is rapidly gaining popularity in metro networks. However, its control plane, primarily based on spanning tree protocol, is not well-suited for the metro and core networks. For such networks, the IETF is evaluating a proposed framework called GELS which uses GMPLS as the control plane for Ethernet data plane. In this paper, we provide a quantitative assessment of GELS for service provider networks. In particular, we perform simulations using COST239 and COST266 networks to evaluate the performance of GELS under normal network conditions, as well as under failure conditions. Under normal network conditions, we find that the use of GELS results in placement of up to 46.4% more bandwidth when compared with native Ethernet control such as RSTP. In terms of LSP acceptance, GELS shows a 45.5% improvement over RSTP. Similarly, average link utilization using GELS is significantly better than the average link utilization when the native Ethernet control plane is used. When considering single element failures, RSTP recovers by converging to a potentially new spanning tree, which may take unacceptably long. In contrast, well-known restoration and protection mechanisms of GMPLS control plane result in much faster recovery. We And that the convergence times exhibited by GELS after single element failures are orders of magnitude better than those obtained when RSTP is used.