Virtually-concatenated data traffic is routed in a network comprising a plurality of nodes, the plurality of nodes including one or more nodes that are differential delay enabled and one or more nodes that are not differential delay enabled. For a given traffic demand to be routed from a source node to a destination node in the network, at least one route is determined for routing the demand between an intermediate node that is differential delay enabled and one of the source node and the destination node that is not differential delay enabled. Also, a set of routes is determined for routing the demand between the intermediate node that is differential delay enabled and at least one other node of the network, that may or may not be differential delay enabled, with each of the routes in the set corresponding to a member of a virtually-concatenated group. The given traffic demand is routed from the source node to the destination node, utilizing the at least one route and the set of routes.