Analysis of GMPLS OSPF-TE Protocol and Its Enhancement for Routing in Optical Networks

摘要

For distributed control, network topology and link resource information is required at the ingress nodes to compute and route optical paths. It is the responsibility of routing protocols to disseminate this information. Generalized MPLS has extended traditional IP routing protocols such as OSPF for explicit path computation and traffic engineering (TE) in optical transport networks. However it is noted that the current version of GMPLS-extended OSPF-TE does not carry sufficient link state information to compute shared mesh restored paths. This paper describes the new extensions to the GMPLS OSPF-TE protocol to support the path computation for shared mesh restoration in optical networks. The efficient methods for aggregation and dissemination of link resource availability and sharing information are proposed. Especially these new extensions support both Shared Risk Link Group (SRLG) disjoint and node disjoint restoration paths, which provides more flexibility to the network operators. The network operators can choose to guarantee recovery from a SRLG failure or from a node/SRLG failure based upon the applications and the service level agreements with their customers. Furthermore, the paper presents an analytical model to estimate the performance of the GMPLS OSPF-TE protocol and the proposed extensions, including control bandwidth and memory requirements.