Hierarchically distributed PCE for backup strategies on an optical network

The application of path computation elements (PCEs) has been widely discussed to reduce route calculation burden from GMPLS nodes. Current PCE proposals, however, have not yet covered path backup schemes, which is prerequisite for providing tremendous capacity such as core optical networks. We already presented a hierarchically distributed path computation element (HDPCE) architecture to improve existing PCE techniques. In this paper, we describe detailed path backup methods performed by HDPCEs to demonstrate the promising potential of HDPCE architecture. The key idea is the interdomain HDPCE, which manages the bridging optical domains, stores shared risk link group (SRLG) information, and discovers accurate disjointed SRLG backups. The proposed technique is sufficiently flexible to allow three variants of path backup methods that are commonly required in commercial networks. We analyze the features and performance of three types of path-backup methods. We also show the superiority of the proposed HDPCE-based backup methods compared to legacy OSPF-based backup methods in terms of path accommodation and processing time.