Data-plane driven fast protection mechanism for MPLS pseudowire services

1. A method, comprising:

transmitting, by a source device in a network, a data packet from the source device to a destination device in the network over a primary pseudowire (PW), wherein the source device and the destination device are terminating provider edge (T-PE) devices;

receiving, at the source device, the data packet returned with a loopback packet identifier in the data packet from the primary PW, in response to a downstream failure, wherein the loop packet identifier is added to the data packet by a device downstream of the source device that detected the downstream failure;

in response to receiving the returned data packet with the loopback packet, retransmitting, by the source device, the data packet to the destination over a backup PW;

receiving, at the source device, an indication that the primary PW is repaired; and

in response, transmitting subsequent data packets over the primary PW.

2. The method as in claim 1 , further comprising:

activating the backup PW in response to receiving the returned data packet with the loopback packet identifier.

3. The method as in claim 1 , wherein the loopback packet identifier is selected from a group comprising a reserved label, a control channel type, or an arbitrary label that identifies loopback data packets to the source.

4. The method as in claim 1 , wherein the loopback packet identifier is below a PW label in a corresponding label stack of the data packet.

5. The method as in claim 1 , further comprising:

signaling the loopback packet identifier via PW signaling.

6. The method as in claim 1 , wherein the primary PW and backup PW are one of either a single-segment pseudowire (SS-PW) or multi-segment pseudowire (MS-PW).

7. The method as in claim 1 , wherein the primary PW is a primary multi-segment pseudowire (MS-PW), and wherein the returned data packet with the loopback packet identifier is originated by an intermediate switching provider edge (S-PE) device along the primary MS-PW.

8. A method, comprising:

detecting a downstream failure of a primary pseudowire (PW) by a device on the primary PW, wherein the device is a terminating provider edge (T-PE) device;

receiving one or more data packets from a source from the failed primary PW at the device;

adding, by the device, a loopback packet identifier to the one or more received data packets;

returning, by the device, the one or more data packets with the loopback packet identifier to the source upstream on the primary PW, wherein the loopback packet identifier added to the one or more returned data packets causes the source to retransmit the one or more returned data packets on a backup PW;

determining, by the device, that the primary PW is repaired; and

transmitting, by the device, an indication that the primary PW is repaired to the source.

9. The method as in claim 8 , wherein the loopback packet identifier is selected from a group comprising a reserved label, a control channel type, or an arbitrary label that identifies loopback data packets to the source.

10. The method as in claim 8 , wherein the loopback packet identifier is below a PW label in a corresponding label stack of the one or more data packets.

11. The method as in claim 8 , wherein the primary PW is one of either a single-segment pseudowire (SS-PW) or multi-segment pseudowire (MS-PW).

12. The method as in claim 8 , wherein the device is on a single-segment pseudowire (SS-PW) or a multi-segment pseudowire (MS-PW).

13. An apparatus, comprising:

one or more network interfaces to communicate within a computer network;

a processor coupled to the network interfaces and configured to execute one or more processes; and

a memory configured to store a process executable by the processor, the process when executed configured to:

transmit a data packet, as a source, to a destination over a primary pseudowire (PW), wherein the source and the destination are terminating provider edge (T-PE) devices;

receive the data packet returned with a loopback packet identifier in the data packet from the primary PW, in response to a downstream failure, wherein the loop packet identifier is added to the data packet by a device downstream of the source device that detected the downstream failure; and

in response to receiving the returned data packet with the loopback packet identifier, retransmit the data packet to the destination over a backup PW;

receive an indication that the primary PW is repaired; and

in response, transmit subsequent data packets over the primary PW.

14. The apparatus as in claim 13 , wherein the process when executed is further configured to:

activate the backup PW in response to receiving the returned data packet with the loopback packet identifier.

15. An apparatus, comprising:

one or more network interfaces to communicate within a computer network; a processor coupled to the network interfaces and configured to execute one or more processes; and

a memory configured to store a process executable by the processor, the process when executed configured to:

detect a downstream failure of a primary pseudowire (PW) as a device on the primary PW, wherein the apparatus is a terminating provider edge (T-PE) device;

receive one or more data packets from a source from the failed primary PW;

add a loopback packet identifier to the one or more received data packets; and

return the one or more data packets with the loopback packet identifier to the source upstream on the primary PW, wherein the loopback packet identifier added to the one or more returned data packets causes the source to retransmit the one or more returned data packets on a backup PW;

determine that the primary PW is repaired; and

transmit an indication that the primary PW is repaired to the source.

16. A system, comprising:

a source configured to transmit one or more data packets to a destination over a primary pseudowire (PW), wherein the source is a first terminating provider edge (T-PE) device; and

a device on the primary PW configured to detect a downstream failure of the primary PW, the device further configured to receive one or more data packets from the source from the failed primary PW, and to return the one or more data packets with a loopback packet identifier to the source upstream on the primary PW, wherein the device is a second T-PE device;

wherein the source is further configured to retransmit the one or more data packets to the destination over a backup PW in response to receiving the one or more returned data packets with the loopback packet identifier added to the returned one or more data packets, determine that the primary PW is repaired, and transmit an indication that the primary PW is repaired to the source.

17. The system as in claim 16 , wherein the source is further configured to activate the backup PW in response to receiving the returned data packet with the loopback packet identifier.

18. The system as in claim 16 , wherein the device is on a single-segment pseudowire (SS-PW) or a T-PE on a multi-segment pseudowire (MS-PW).