As GMPLS and its supporting set of protocols develop into aviable control plane for optical networks, an important function that they will need to support will be the protection and restoration function that has been a major feature of legacy optical networks. A network with a robust set of protection and restoration mechanisms will be able to support data traffic while allowing faster recovery from failures than can be obtained using layer 3 rerouting. Several models have been proposed for protection with GMPLS using shared backup paths. This previous work has not investigated the effect on recovery time critical to the service or the number of backup paths that are required to meet a desired level of performance. Using both restoration time and recovery blocking probability, we have developed a new analytic model for GMPLS-based recovery in M:N protection groups. Furthermore, we show that smaller backup paths can be reserved by capturing the effect of multiple failures in the case of M:N shared protection with revertive mode in an optical network with a GMPLS control plane.