Telecommunication networks are subject to failures which may be complex. Fast-reroute implementations have been proposed for Multiprotocol Label Switching (MPLS) networks to make it possible to reroute traffic locally in case of failure. Hence, to each link is associated a bypass tunnel usable if the link fails. These protection tunnels can be pre-calculated in a centralized manner, that ensures faster traffic restoration and global resource optimization. This paper presents mathematical models and algorithms to compute fast-reroute protection tunnels. These bypass tunnels are computed with the aim of minimizing the congestion in any failure case. As a result, the solution proposed ensures a satisfactory quality of service for any of the planned events, as well as a good robustness to traffic variations and to unplanned events. Numerical tests show the effectiveness of the proposed approach.