Make-before-break mechanism for label switched paths

1. A method, comprising:

determining, by a device in a network, that traffic sent via a first label switched path should be sent via a new label switched path;

sending, by the device, a request for an interface binding label for each node in the new label switched path via a RECORD ROUTE object of a Resource Reservation Protocol (RSVP) PATH message;

receiving, at the device, the interface binding label for each node in the new label switched path via a Resource Reservation Protocol (RSVP) RESV message, wherein the interface binding label for each node in the new label switched path is recorded in a RECORD ROUTE object (RRO) of the RSVP RESV message to create a label stack for the new label switch path;

sending, by the device, the traffic along the new label switched path using a label stack that indicates one or more preprogrammed interface binding labels, wherein the one or more interface binding labels are local labels that are each bound to a specific RSVP Traffic Engineering (TE) interface of one or more corresponding nodes along the new label switched path, and a particular node along the new label switched path is configured to forward the traffic via a particular TE interface of the node based on a corresponding interface binding label; and

completing, by the device, a switchover from the first path to the new label switched path.

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

requesting, by the device, the one or more interface binding labels for traffic engineering interfaces of the nodes via an RSVP PATH message.

3. The method as in claim 2 , wherein the device receives the one or more interface binding labels for the traffic engineering interfaces of the nodes via an RSVP RESV message.

4. The method as in claim 1 , wherein the device sends the traffic along the new label switched path using the label corresponding to the new label switched path after expiration of a timer configured to afford the nodes time to install a path label.

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

receiving, at the device, data indicative of the interface binding labels for the traffic engineering interfaces of the nodes along the new label switched path.

6. A method, comprising:

determining, by a device in a network, an interface binding label for a traffic engineering interface of the device, wherein the interface binding label is pre-programmed as a local label that is bound to a specific—RSVP Traffic Engineering (TE) interface at the device;

receiving, at the device, a request for the interface binding label via a RECORD ROUTE object of a Resource Reservation Protocol (RSVP) PATH message;

providing, by the device, the interface binding label towards a head-end node of a path in the network by recording the interface binding label in a RECORD ROUTE object (RRO) of an RSVP RESV message, wherein the RSVP RESV message is received at the head-end node and records the interface binding label in the RRO to create a label stack for a new label switch path;

receiving, at the device, a packet that includes the interface binding label; and

forwarding, by the device, the packet via the traffic engineering interface of the device.

7. The method as in claim 6 , wherein the packet comprises a label stack that indicates a segment routing adjacency segment, and wherein the device forwards the packet via the segment routing adjacency segment.

8. An apparatus, comprising:

one or more network interfaces to communicate with a network;

a processor coupled to the one or more 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:

determine that traffic sent via a first label switched path should be sent via a new label switched path;

send a request for the interface binding label for each node in the new label switched path via a RECORD ROUTE object of a Resource Reservation Protocol (RSVP) PATH message;

receive an interface binding label for each node in the new label switched path via a Resource Reservation Protocol (RSVP) RESV message, wherein the interface binding label for each node in the new label switched path is recorded in a RECORD ROUTE object (RRO) of the RSVP RESV message to create a label stack for the new label switch path;

send the traffic along the new label switched path using a label stack that indicates one or more preprogrammed interface binding labels, wherein the one or more interface binding labels are local labels that are each bound to a specific RSVP-Traffic Engineering (TE) interface of one or more corresponding nodes along the new label switched path, and a particular node along the new label switched path is configured to forward the traffic via a particular TE interface of the node based on a corresponding interface binding label; and

complete a switchover from the first path to the new label switched path.

9. The apparatus as in claim 8 , wherein the process when executed is further configured to:

request the one or more interface binding labels for traffic engineering interfaces of the nodes via a RSVP PATH message.

10. The apparatus as in claim 9 , wherein the apparatus receives data indicative of the one or more interface binding labels for the traffic engineering interfaces of the nodes via an RSVP RESV message.

11. The apparatus as in claim 8 , wherein the apparatus sends the traffic along the new label switched path using the label corresponding to the new label switched path after expiration of a timer configured to afford the nodes time to install the path label.

12. The apparatus as in claim 8 , wherein the process when executed is further operable to:

receive data indicative of the one or more interface binding labels for traffic engineering interfaces of nodes along the new label switched path.

13. An apparatus, comprising:

one or more network interfaces to communicate with a network;

a processor coupled to the one or more 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:

determine an interface binding label for a traffic engineering interface of the apparatus, wherein the interface binding label is pre-programmed as a local label that is bound to a specific—RSVP Traffic Engineering (TE) interface at the apparatus;

receive a request for the interface binding label via a RECORD ROUTE object of Resource Reservation Protocol (RSVP) PATH message;

provide an interface binding label towards a head-end node of a path in the network by recording the interface binding label in a RECORD ROUTE object (RRO) of an RSVP RESV message, wherein the RSVP RESV message is received at the head-end node and records the interface binding label in the RRO to create a label stack for a new label switch path;

receive a packet that includes the interface binding label; and

forward the packet via the traffic engineering interface of the apparatus.

14. The apparatus as in claim 13 , wherein the packet comprises a label stack that indicates a segment routing adjacency segment, and wherein the apparatus forwards the packet via the segment routing adjacency segment.