It is expected that GMPLS-based recovery could become a viable option for obtaining faster restoration than layer 3 rerouting. Even though dedicated restoration ensures restorability of connections, exclusive use of dedicated scheme would result in wasting network resources, especially in case of providing for multiple failures. A range of restoration schemes have been proposed that use the concept of sharing capacity to improve efficiency. However, the case of multiple simultaneous failures has not been considered. In this paper we propose a hierarchical scheme for handling multiple simultaneous failures, where hierarchical Shared Risk Link Groups (SRLGs) are applied. We also introduce Backup Group Multiplexing (BGM) into our hierarchical scheme to precipitate the restoration of multiple Label Switched Paths (LSPs) with failures all at once. Furthermore, the proposed scheme selects a backup path with enough resources to satisfy renegotiated Quality of Service (QoS) of each backup group, among M backup paths. Our simulation results demonstrate that our scheme utilizes bandwidth more efficiently through multiplexing gain.
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