Apparatus and method for flow-level demultiplexing

A packet routing system is disclosed that allows for efficient transfer of data flows from router (102) to router (104) with use of supertrunking (112). The router (102) that receives (502) a data flow (220) inputs the packets of the data flow, determines (504) the logical output port corresponding to the data flow, assigns the entire data flow to a physical output port within the logical output port with use of a load balancing function, encapsulates each packet within a Packet Forwarding Header (PFH) and a Rotator Information Unit (RIU) header that identifies the assigned physical output port, and outputs (510) the encapsulated packets of the data flow to the assigned physical output port. The assigned physical output port removes the PFH and the RIU header from each packet and outputs the packets to a physical link. The router (104) that receives the packets can treat the packets of the particular data flow like typical packets since all the packets of the same data flow traverse the same physical link resulting in no mis-ordering of packets.