A state-based availability model to shared mesh protection in MPLS-TP networks with preemption support

The emerging MPLS-TP standard defines new and important recovery requirements for networks deployed with the MPLS technology. MPLS provides several facilities to support protection, but many parameters such as holding and setup priorities as well as the amount of spare capacity must be configured in order to achieve the desired protection level. In this direction, this paper proposes a state-based availability model to help the design of shared-mesh protection schemes for packed-switched paths deployed using MPLS technology. The steady-state probabilities of failure-states in a network can be determined using the MTBF and MTTR of the physical links and other components. Based on this information, the state-based model determines the impact of each failure-state on the availability of all protected paths transported by the network. Using our model, we propose a backup resource planning algorithm that computes the minimum spare capacity required to achieve the desired availability of all protected paths, as well as the strategy for assigning priorities to the backup paths.