Virtually-concatenated data traffic is routed in a network comprising a plurality of nodes. For a given traffic demand to be routed from a source node to a destination node in the network, an initial candidate path set satisfying a differential delay constraint is determined by arranging a plurality of paths in order of increasing delay and selecting a particular subset of the plurality of paths as the initial candidate set. A determination is then made as to whether the initial candidate path set is able to support a bandwidth requirement of the traffic demand. If the initial candidate path set is able to support the bandwidth requirement of the traffic demand, the initial candidate path set is utilized to route the traffic demand. Otherwise, the process is repeated for one or more additional iterations, with a different candidate path set satisfying the differential delay constraint being selected for a given additional iteration by application of a sliding-window function to the plurality of paths arranged in order of increasing delay, until a different candidate path satisfying the differential delay constraint is determined to support the bandwidth requirement of the traffic demand.