Patent ID: 7843924

Claim:
A method of operating a node in a label switch telecommunications network, the method comprising: storing a data structure indicating, for a working path passing through said node, a forward message input label, a forward message output label and an association therebetween; receiving a message at said node; identifying an input message label attached to the message; replacing the input message label with an output message label; sending the message to another node in said network; wherein said label replacing comprises: determining whether said message is a forward message or a return message; and in the case of determining that said message is a forward message: i) searching said data structure to find a forward message input label matching said input message label; ii) reading said data structure to identify the forward message output label associated with the found forward message input label; and iii) replacing the input message label with the identified forward message output label; in the case of determining that said message is a return message: i) searching said data structure to find a forward message output label matching said input message label; ii) reading the same data structure to identify the forward message input label associated with the found forward message output label; and iii) replacing the input message label with said forward message input label.