An indication of a combination of a Shared Risk Link Group identifier and a node identifier for each of a plurality of links through at least one network and between a source network device and a destination network device is received at a network device. A primary path through the at least one network between the source network device and the destination network device is determined at the network device. The primary path comprises a first subset of the plurality of links through the at least one network. A back-up path through the at least one network between the source network device and the destination network device is determined at the network device. The back-up path comprises a second subset of the plurality of links through the at least one network.