Virtual ldp session

Abstract

A receiving node receives a virtual LDP initialization (vInit) message from a first node, where the vinit message comprises a request to establish a vLDP session between a requesting node and a target node. If the receiving node does not own a destination address of the vinit message, the receiving node is determined to be a relay node. The relay node inserts a relay label into the vinit message, where the relay label is an outgoing label that the relay node uses to reach the first node, and forwards the vinit message toward the destination address. If the receiving node owns the destination address, the receiving node is determined to be the target node, which extracts a stack of relay labels from the vinit message. The relay labels are used to define a return path to the requesting node for messages transmitted over the vLDP session.

What is claimed is: 
     
         1 . A method comprising:
 a requesting node sending a virtual Label Distribution Protocol initialization (vinit) message towards a target node, wherein the vinit message comprises:   a request to establish a virtual Label Distribution Protocol (vLDP) session between the requesting node the target node;   an address for the requesting node and an address for the target node, and;   a vLDP session ID;   the requesting node receiving another vinit message from another node after sending the vinit message, wherein the other vinit message comprises the vLDP session ID.   
     
     
         2 . The method of  claim 1  further comprising:
 the requesting node extracting a stack of one or more labels from the other vinit message; 
 the requesting node storing the extracted stack in memory; 
 the requesting node adding another label to the stored stack to create a modified stack in memory, wherein the other label is used by the requesting node to reach the other node. 
 
     
     
         3 . The method of  claim 2  wherein the one or more relay labels were provided by one or more relay nodes and define an LDP path between the target node and the requesting node for messages transmitted over the vLDP session, and wherein the one or more relay nodes are located between the requesting node and the target node. 
     
     
         4 . The method of  claim 2  further comprising mapping the vLDP session ID with the modified stack in memory. 
     
     
         5 . The method of  claim 3  further comprising:
 the requesting node generating a message; 
 the requesting node attaching a copy of the modified stack to the message; 
 the requesting node forwarding the message with attached modified stack to the other node. 
 
     
     
         6 . The method of  claim 1  wherein the requesting and target nodes are contained in separate network segments. 
     
     
         7 . The method of  claim 1  further comprising:
 the requesting node determining the target node is unreachable; 
 the requesting node generating the vinit message in response to determining the target node is unreachable. 
 
     
     
         8 . A node comprising:
 one or more processors; and   a memory to store instructions executable by the one or more processors, to perform operations comprising:   sending a virtual Label Distribution Protocol initialization (vinit) message towards a target node, wherein the vinit message comprises:   a request to establish a virtual Label Distribution Protocol (vLDP) session between the node the target node;   an address for the node and an address for the target node, and;   a vLDP session ID;   receiving another vinit message from another node after sending the vinit message, wherein the other vinit message comprises the vLDP session ID.   
     
     
         9 . The node of  claim 8  wherein the operations further comprise:
 extracting a stack of one or more labels from the other vinit message; 
 storing the extracted stack in memory; 
 adding another label to the stored stack to create a modified stack in memory, wherein the other label is used by the requesting node to reach the other node. 
 
     
     
         10 . The node of  claim 9  wherein the one or more relay labels were provided by one or more relay nodes and define an LDP path between the target node and the node for messages transmitted over the vLDP session, and wherein the one or more relay nodes are located between the node and the target node. 
     
     
         11 . The node of  claim 10  wherein the operations further comprise mapping the vLDP session ID with the modified stack in memory. 
     
     
         12 . The node of  claim 11  wherein the operations further comprise generating a message;
 attaching a copy of the modified stack to the message; 
 forwarding the message with attached modified stack to the other node. 
 
     
     
         13 . The node of  claim 8  wherein the operations further comprise:
 determining the target node is unreachable; 
 generating the vinit message in response to determining the target node is unreachable. 
 
     
     
         14 . One or more computer-readable storage media storing instructions that, when executed by one or more processors of a node, cause the one or more processors to perform operations comprising:
 sending a virtual Label Distribution Protocol initialization (vinit) message towards a target node, wherein the vinit message comprises:   a request to establish a virtual Label Distribution Protocol (vLDP) session between the node the target node;   an address for the node and an address for the target node, and;   a vLDP session ID;   receiving another vinit message from another node after sending the vinit message, wherein the other vinit message comprises the vLDP session ID.   
     
     
         15 . The one or more computer-readable storage media of  claim 14  wherein the operations further comprise:
 extracting a stack of one or more labels from the other vinit message; 
 storing the extracted stack in memory; 
 adding another label to the stored stack to create a modified stack in memory, wherein the other label is used by the requesting node to reach the other node. 
 
     
     
         16 . The one or more computer-readable storage media of  claim 15  wherein the operations further comprise mapping the vLDP session ID with the modified stack in memory. 
     
     
         17 . The one or more computer-readable storage media of  claim 15  wherein the operations further comprise:
 generating a message; 
 attaching a copy of the modified stack to the message; 
 forwarding the message with attached modified stack to the other node. 
 
     
     
         18 . The one or more computer-readable storage media of  claim 14  wherein the operations further comprise:
 determining the target node is unreachable; 
 generating the vinit message in response to determining the target node is unreachable. 
 
     
     
         19 . The one or more computer-readable storage media of  claim 15  wherein the one or more relay labels were provided by one or more relay nodes and define an LDP path between the target node and the node for messages transmitted over the vLDP session, and wherein the one or more relay nodes are located between the node and the target node. 
     
     
         20 . The one or more computer-readable storage media of  claim 14  wherein the node and target node are contained in separate network segments.