Capacity requirements for the facility backup option in MPLS fast reroute

MPLS fast reroute (MPLS-FRR) mechanisms deviate the traffic in case of network failures at the router which is closest to the outage location to achieve an extremely fast reaction time. We review the facility backup that is an option for MPLS-FRR that deviates the traffic via a bypass around the failed elements. Basically, the backup path can take the shortest path that avoids the outage location from the point of local repair to the merge point with the primary path. We suggest two new simple modifications that lead to a new path layout which can be implemented by the facility backup. We evaluate the backup capacity requirements, the length of the backup paths, and the number of backup paths in a parametric study regarding the network characteristics. Our proposals save a considerable amount of backup capacity compared to the standard mechanisms. They are suitable for application in practice since they are simple and conform to the standards