Consistent with the present disclosure, client data, which may include multiplexed data sub-streams, is supplied to an ingress node of a network. Each sub-stream typically has a corresponding data rate, i.e., an original data rate, prior to multiplexing. The client data is encapsulated in a plurality of successive frames that are output from the ingress node and propagate, typically through one or more intermediate nodes, to an egress node. At the egress node, data rates associated with the sub-streams included in each frame are determined based on the amount of client data in each frame. The data rates are then averaged over a given number of frames to thereby filter any wander or deviation in the client data rate. Based on the averaged data rate, justification opportunities are added to the client data in each sub-stream, which are then multiplexed into frames that are output from the egress node. By including the justification opportunities, the effective rate of each sub-stream may be set equal to the original data rate when the sub-streams are demultiplexed after being output from the egress node. An advantage of the present disclosure is that the justification opportunities, are not generated based solely on clock signals generated by PLL circuits. As a result, fewer PLL circuits are required, thereby simplifying system design and minimizing power consumption.