Method for reestablishing label switched path, and network apparatus

A network apparatus, comprising:

• a processor;
• and
• a memory containing instructions executable by the processor;
• and
• the memory and the processor configuring the network apparatus to:
• detect a breakage of a label distribution protocol, LDP, session between the network apparatus and a first downstream network apparatus, the first downstream network apparatus being in a first label switched path, LSP, from the network apparatus to a destination network apparatus;
• calculate a second LSP from the network apparatus to the destination network apparatus, by using a constrained shortest path first, CSPF, algorithm;
• and
• replace the first LSP with the second LSP.

A computer readable storage medium having a computer program stored thereon, the computer program executable by a device to cause the device to:

• detect a breakage of a label distribution protocol, LDP, session between the network apparatus and a first downstream network apparatus, the first downstream network apparatus being in a first label switched path, LSP, from the network apparatus to a destination network apparatus;
• calculate a second LSP from the network apparatus to the destination network apparatus, by using a constrained shortest path first, CSPF, algorithm;
• and
• replace the first LSP with the second LSP.