Dynamic establishment of virtual circuits using multisegment pseudowires

Abstract

The present invention provides a technique for automatically establishing a virtual circuit from one edge device to another through a core network. The virtual circuit may comprise one or more pseudowire segments. These pseudowire segments extend between adjacent edge and core devices within the core network. Pseudowire segments through the core network are automatically stitched together as a setup message is forwarded from a first edge device to a second edge device through the core network. A virtual circuit is established in one direction, and packets are forwarded in an opposite direction. With the present invention, a virtual circuit comprising any number of pseudowire segments, as well as two attachment circuits, may be established in an automatic and efficient manner upon being initiated by the first edge device.

What is claimed is: 
     
         1 . A method of dynamically establishing a multi-segment pseudowire connection, comprising, at a first edge device having destination information for a second edge device:
 determining, based on the destination information, a next hop toward the second edge device, the next hop being a core device;   creating a setup message comprising a source address associated with the first edge device and the destination information;   sending the setup message to the next hop to initiate automatic establishment of the multi-segment pseudowire connection; and   associating a first pseudowire segment extending from the first edge device to the core device with the multi-segment pseudowire connection.   
     
     
         2 . The method of  claim 1 , comprising, at the core device:
 receiving the setup message;   determining a further hop toward the second edge device based on the destination information in the received setup message;   sending the setup message to the further hop to further automatic establishment of the multi-segment pseudowire connection; and   associating a second pseudowire segment with the first pseudowire segment at the core device such that packets arriving over the second pseudowire segment are forwarded over the first pseudowire segment by the core device.   
     
     
         3 . The method of  claim 2 , comprising, at at least one further core device:
 receiving from a previous hop, the setup message;   determining a next hop toward the second edge device based on the destination information in the received setup message;   sending the setup message to the next hop to further automatic establishment of the multi-segment pseudowire connection; and   associating a further pseudowire segment with a previous pseudowire segment extending from the previous hop to the at least one further core device such that packets arriving over the further pseudowire segment are forwarded over the previous pseudowire segment by the further core device.   
     
     
         4 . The method of  claim 2 , further comprising, at the second edge device:
 receiving, from a previous hop, the setup message, the previous hop being a core device; and   determining that the setup message is intended for the second edge device based on the destination information.   
     
     
         5 . The method of  claim 4 , further comprising, at the second edge device, associating the second pseudowire segment extending from the previous hop to the second edge device with an attachment circuit supported by the second edge device such that packets arriving over the attachment circuit are forwarded over the second pseudowire segment to implement part of the multi-segment pseudowire connection. 
     
     
         6 . The method of  claim 2 , wherein the destination information comprises a destination address and an identifier associated with an endpoint of the multi-segment pseudowire connection. 
     
     
         7 . The method of  claim 6 , wherein the identifier associated with the endpoint of the multi-segment pseudowire connection comprises an identifier associated with an attachment circuit supported by the second edge device such that packets arriving over the attachment circuit are forwarded over the second pseudowire segment to implement part of the multi-segment pseudowire connection. 
     
     
         8 . The method of  claim 6 , comprising, at the second edge device, comprising:
 receiving, from a previous hop, the setup message;   determining that the setup message is intended for the second edge device based on the destination information; and   verifying that the identifier associated with the endpoint of the multi-segment pseudowire connection is a valid identifier associated with the second edge device.   
     
     
         9 . The method of  claim 1 , wherein the first edge device is configured to support an attachment circuit, further comprising the first edge device associating the first pseudowire segment with the attachment circuit such that packets arriving over the first pseudowire segment are forwarded over the attachment circuit to implement part of the multi-segment pseudowire connection. 
     
     
         10 . The method of  claim 1 , comprising receiving provisioning information for establishing a virtual circuit with the second edge device at the first edge device, the provisioning information identifying the destination information associated with the second edge device, the destination information comprising an address and an identifier associated with an endpoint of the multi-segment pseudowire connection. 
     
     
         11 . The method of  claim 10 , wherein the identifier associated with an endpoint of the multi-segment pseudowire connection comprises an identifier associated with an attachment circuit supported by the second edge device. 
     
     
         12 . The method of  claim 10 , wherein the first edge device determines the next hop and creates the setup message responsive to receiving the provisioning information. 
     
     
         13 . The method of  claim 1 , wherein the first edge device determining the next hop toward the second edge device based on the destination information comprises the first edge device accessing a routing table using the destination information to determine the next hop. 
     
     
         14 . The method of  claim 2 , wherein the core device determining the next hop toward the second edge device based on the destination information in the received setup message comprises the core device accessing a routing table using the destination information to determine the next hop. 
     
     
         15 . The method of  claim 2 , wherein:
 the destination information comprises an address and an identifier associated with an endpoint of the multi-segment pseudowire connection; and   the core device determining the next hop toward the second edge device based on the destination information in the received setup message comprises the core device accessing a routing table using the address to determine the next hop.   
     
     
         16 . The method of  claim 3 , wherein the at least one further core device determining the next hop toward the second edge device based on the destination information in the received setup message comprises the at least one further core device accessing a routing table using the destination information to determine the next hop. 
     
     
         17 . The method of  claim 3 , wherein:
 the destination information comprises an address and an identifier associated with an endpoint of the multi-segment pseudowire connection; and   the at least one further core device determining the next hop toward the second edge device based on the destination information in the received setup message comprises the at least one further core device accessing a routing table using the address to determine the next hop.   
     
     
         18 . The method of  claim 1 , wherein the setup message is routed hop-by-hop through a core network to the second edge device and, at each hop within the core network, a pseudowire segment extending to a next hop is associated with a pseudowire segment extending from a previous hop, such that packets arriving over the pseudowire segment extending to the next hop are forwarded over the pseudowire segment extending from the previous hop. 
     
     
         19 . The method of  claim 10 , wherein the setup message is routed hop-by-hop through a core network to the second edge device and, at each hop within the core network, a pseudowire segment extending to a next hop is associated with a pseudowire segment extending from a previous hop, such that packets arriving over the pseudowire segment extending to the next hop are forwarded over the pseudowire segment extending from the previous hop to facilitate part of the virtual circuit. 
     
     
         20 . The method of  claim 10 , wherein the setup message is routed hop-by-hop through a core network to the second edge device and, at the second edge device, an attachment circuit supported by the second edge device is associated with a pseudowire segment extending from a previous hop, such that packets arriving over the attachment circuit are forwarded over the pseudowire segment extending from the previous hop to facilitate part of the virtual circuit.