This paper proposes a novel framework of shared protection, namely Group Shared Protection (GSP), in mesh Wavelength Division Multiplexing (WDM) networks with dynamically arrived connection requests. Based on the (M:N) n control architecture, GSP has n mutually independent protection groups, each of which containing N SRLG-disjoint working paths protected by M protection paths. Due to the SRLG-disjointedness of the working paths in each protection group, GSP not only allows the spare capacity

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... be totally sharable among the corresponding working paths, but also reduces the number of working paths affected due to a single link failure. Based on the framework, an Integer Linear Program (ILP) formulation that can optimally reconfigure the spare capacity for a specific protection group whenever a working-protection path-pair joins is proposed. Two heuristics namely link-shared (LSP) and ringshared protection (RSP) are introduced for further compromising the performance and the computation complexity. The proposed schemes are compared with a reported one, namely Successive Survivable Routing (SSR). The experimental results show that LSP, RSP and SSR yield similar performance in terms of resource sharing, whereas ILP outperforms all of them by (6-16)%. Due to the limited number of working paths in each protection group, ILP can handle dynamically arrived connection request in a reasonable amount of time. Also, we find that the number of affected working paths in GSP is about half of that in SSR. We conclude that GSP provides a scalable and efficient solution for dynamic spare capacity reconfiguration following the (M:N) n control architecture.