Patent ID: 8144710

Claim:
A method of partitioning a header stack of a traffic unit, said header stack conforming to a label switching protocol and comprising a plurality of headers each of which comprises a label field to which a label value is assignable to enable a label switching node to operate on said traffic unit in a respective operational domain of a label switching protocol communications network in a communications system comprising a plurality of label switching protocol communications networks, the method comprising of: receiving said traffic unit at an edge node of a first operational domain of said communication system; and processing the header stack of said traffic unit at the edge node to add a new stack entry having a label field comprising a value which marks the boundary of one or more header stack entries forming a first stack domain of said header stack configurable by one or more label switching nodes arranged to operate on said traffic unit in said first operational domain of said communications system and at least one other stack domain of said header stack in which one or more header stack entries are configurable by one or more label switching nodes belonging to another operational domain of said communications system.