Protection switching in multiprotocol label switching (MPLS) networks

1. A method for protection switching in a multi-protocol label switching (MPLS) ring network with a protection label switch path that is shared by multiple working label switch paths, the method comprising:

receiving, on a working label switch path, a packet intended for transmission towards a disconnected adjacent node on the working label switch path;

adding, to the received packet, a protection label and a merge label in response to determining the received packet is intended for the transmission towards the disconnected adjacent node on the working label switch path, wherein the merge label uniquely identifies the working label switch path on which the packet is received and is known to nodes on the working label switch path identified by the merge label; and

transmitting the packet on the protection label switch path.

2. The method of claim 1 , wherein adding the merge label to the received packet further comprises:

determining a forwarding equivalence class of the packet;

determining the merge label from forwarding information that associates the forwarding equivalence class with the merge label and a push label operation; and

performing a push label operation to add the merge label to the received packet.

3. The method of claim 1 , wherein adding the merge label to the received packet further comprises:

determining a working label of the received packet;

determining the merge label from forwarding information that associates the working label with the merge label and a swap label operation; and

performing a swap label operation to replace the working label of the packet with the merge label.

4. The method of claim 3 , wherein the merge label is the same as the working label.

5. The method of claim 1 , further comprising, prior to receiving the packet,

detecting disconnection from the adjacent node on the working label switch path; and

upon the detection, blocking any packet received on the protection label switch path from the adjacent node.

6. The method of claim 5 , wherein the disconnection is due to a failure of the adjacent node or a failure of a link leading to the adjacent node.

7. The method of claim 1 , comprising:

assigning a working label, the merge label and the protection label to each node on the working label switch path.

8. A network device for protection switching in a multi-protocol label switching (MPLS) ring network with a protection label switch path shared by multiple working label switch paths, the network device comprising:

a memory to store forwarding information;

a receiving unit to receive, on a working label switch path, a packet intended for transmission towards a disconnected adjacent node on the working label switch path;

a processing unit to add, to the received packet, a protection label and a merge label based on the forwarding information and in response to determining the received packet is intended for the transmission towards the disconnected adjacent node on the working label switch path, wherein the merge label uniquely identifies the working label switch path on which the packet is received and is known to nodes on the working label switch path identified by the merge label; and

a transmitting unit to transmit the packet on the protection label switch path.

9. The network device of claim 8 , wherein a working label, the merge label and the protection label are assigned to each node on the working label switch path.

10. A method for protection switching in a multi-protocol label switching (MPLS) ring network having a protection label switch path shared by multiple working label switch paths, the method comprising:

receiving, on the protection label switch path, a packet with a protection label and a merge label, wherein the merge label uniquely identifies a working label switch path in the network and is known to nodes on the working label switch path identified by the merge label;

removing the protection label from the packet and replacing the merge label with a working label, wherein the working label is associated with the working label switch path uniquely identified by the merge label; and

transmitting the packet on the working label switch path.

11. The method of claim 10 , wherein replacing the merge label with the working label further comprises:

determining the working label from forwarding information that associates the merge label with the working label and a swap label operation; and

performing a swap label operation to replace the merge label with the working label.

12. The method of claim 10 , wherein the merge label is the same as the working label, and the working label is also used by other network devices in the network.

13. The method of claim 10 , further comprising:

detecting disconnection from the adjacent on the working label switch path; and

upon the detection, updating forwarding information to associate the protection label of the packet with a pop operation.

14. The method of claim 13 , wherein the disconnection is due to a failure of the adjacent node or a failure of a link leading to the adjacent node.

15. The method of claim 10 , comprising:

assigning a working label, the merge label and the protection label to each node on the working label switch path.

16. A network device for protection switching in a multi-protocol label switching (MPLS) ring network having a protection label switch path shared by multiple working label switch paths, the network device comprising:

a memory to store forwarding information;

a receiving unit to receive, on the protection label switch path, a packet with a protection label and a merge label, wherein the merge label uniquely identifies a working label switch path in the network and is known to nodes on the working label switch path identified by the merge label;

a processing unit to remove the protection label from the packet and replace the merge label with a working label based on the forwarding information, wherein the working label is associated with the working label switch path identified by the merge label; and

a transmitting unit to transmit the packet on the working label switch path.

17. The network device of claim 16 , wherein a working label, the merge label and the protection label are assigned to each node on the working label switch path.