Improving Service Availability in ERP Based Mesh Networks
Ethernet Ring Protection (ERP) has recently emerged to provide protection switching for Ethernet ring topologies with sub-50 ms failover capabilities. In addition to Ethernet's cost-effectiveness and simplicity, ERP's promise to also provide protection in mesh packet transport networks positions Ethernet as a prominent competitor to conventional SONET/SDH and the technology of choice for carrier networks. Higher service availability, however, in ERP has been challenged by the issue of network partitioning caused by concurrent failures. In this paper, the authors show that in a network designed to withstand only single failure situations, the service availability in the presence of dual failures is affected by the design method, i.e., the RPL placement as well as the selection of ring hierarchy.