A packet network employs restorable routing with service level guarantees. Restorable routing generates two disjoint paths through a network of nodes interconnected by links for a connection request demand between and ingress-egress node pair. Restorable routing employs minimum interference criteria to generate the two disjoint paths such that two disjoint paths cause little or no interference with demands of future connection requests between different ingress-egress pairs. Restorable routing generates maximum 2-route flows for the network ingress-egress node pairs to determine corresponding sets of 2-critical links. A reduced network is formed, its links are weighted based on criticality indices generated from the sets of 2-critical links, and the relatively optimal two disjoint paths are computed for the connection request. One of the two disjoint paths is selected as an active path for routing data of the connection request, and the other disjoint path is selected as the backup path.