US Patent 9246801 Transmitting packet label contexts within computer networks

In general, techniques are described for transmitting context information defining contexts for packet labels in a network. More specifically, a network device, e.g., a router, implements the context transmission techniques to facilitate debugging or troubleshooting of the network. The network device may comprise an interface card that receives a Multi-Protocol Label Switching (MPLS) data unit from another network device in accordance with a label switching protocol. The data unit may include a label stack affixed to a payload. The label stack may include one or more MPLS labels and context information associated with at least one of these labels, The interface card may, when forwarding the data unit, parse the data unit to determine the context information and then forward the data unit in accordance with these MPLS labels. A control unit included within the network device may record the forwarding of the data unit and the determined context information.