Handling entropy labels when stitching label-switched paths

A method comprising:

• determining, by a notional ingress routing device, whether a packet, received from a previous label switched path (LSP) segment of an end-to-end LSP for the packet, is encapsulated by a label stack that includes an entropy label, wherein the notional ingress routing comprises a routing device of a current LSP segment of the end-to-end LSP, wherein the current LSP segment includes a plurality of routing devices;
• when the current LSP segment supports entropy labels and the label stack does not include an entropy label;
• adding an entropy label to the label stack of the packet;
• and
• forwarding the packet including the entropy label along the current LSP segment;
• and
• when the current LSP segment does not support entropy labels, forwarding the packet without the entropy label along the current LSP segment.

A stitching point routing device that stitches a previous label switched path (LSP) segment of an end-to-end LSP to a next LSP segment of the end-to-end LSP, the stitching point routing device comprising:

• one or more network interfaces configured to receive packets via the previous LSP segment and send packets via the next LSP segment, wherein the next LSP segment includes a plurality of routing devices;
• and
• one or more processors configured to:
• determine whether the plurality of routing devices of the next LSP segment supports entropy labels,
• determine whether a packet received from the previous LSP segment is encapsulated by a label stack including an entropy label,
• when the plurality of routing devices of the next LSP segment does not support entropy labels and when the packet is encapsulated by the label stack including the entropy label, remove the entropy label from the label stack,
• when the plurality of routing devices of the next LSP segment supports entropy labels and when the packet is not encapsulated by the label stack including the entropy label, add an entropy label to the label stack, and
• forward the packet along the next LSP segment.

A computer-readable storage medium having stored thereon instructions that, when executed, cause a processor of a stitching point routing device that stitches a previous label switched path (LSP) segment of an end-to-end LSP to a next LSP segment of the end-to-end LSP, wherein the next LSP segment includes a plurality of routing devices, to:

• determine whether the plurality of routing devices of the next LSP segment supports entropy labels;
• determine whether a packet received from the previous LSP segment is encapsulated by a label stack including an entropy label;
• when the plurality of routing devices of the next LSP segment does not support entropy labels and when the packet is encapsulated by the label stack including the entropy label, remove the entropy label from the label stack;
• when the plurality of routing devices of the next LSP segment supports entropy labels and when the packet is not encapsulated by the label stack including the entropy label, add an entropy label to the label stack;
• and
• forward the packet along the next LSP segment.