System, Device and Method for Managing Alternate Site Switching in an Optical Communication System

Abstract

A system, device, and method for managing alternate site switching in an optical communication system recovers from failures/degradations that are uncorrected by the core optical communication network. When an uncorrected failure/degradation is detected, communications for a protected end-system are switched from a primary end-system to a backup end-system. The backup end-system may be selected a priori, for example, during connection establishment, in order to reduce switching time once a decision has been made to switch communications from the primary end-system to the backup end-system. Provisions are made for completing the alternate site switching within a specified amount of time. Load balancing may be used to further reduce switching time from the primary end-system to the backup end-system. This alternate site switching augments the various protection mechanisms provided by the core optical communication network in order to provide end-to-end protection for the optical communication path.

1 - 47 . (canceled) 
     
     
         48 . Apparatus for managing alternate site switching where a protected end-system of a user is in communication with a primary end-system of the user over an optical communication network of a service provider, including:
 backup end-system designation circuitry which designates at least one backup end-system to back up the primary end-system;   failover tree construction circuitry which constructs a failover tree to the at least one backup end-system, the failover tree including at least one node in the optical communication network of the service provider, the failover tree being constructed prior to detection of failure or degradation of the primary end-system; and   signaling circuitry which sends a setup request message to the at least one node in the optical communication network of the service provider specifying the failover tree structure,   whereby the optical communication network of the service provider is prepared to respond to a failure in the user network.   
     
     
         49 . The apparatus of  claim 48  wherein the backup end-system designation circuitry is operably coupled to receive the setup request from the protected end-system specifying the at least one backup end-system. 
     
     
         50 . The apparatus of  claim 48  wherein the backup end-system designation circuitry is operably coupled to automatically discover the at least one backup end-system using a predetermined auto-discovery mechanism. 
     
     
         51 . The apparatus of  claim 48  wherein the failover tree construction circuitry is operably coupled to determine a root node for the failover tree by identifying a candidate node that is within a predetermined number of hops from the at least one backup end-system, constructing a shortest-path spanning tree from the candidate node to the at least one backup end-system, and selecting the candidate node as the root node if and only if the shortest-path spanning tree does not include any link from the protected end-system to the candidate node. 
     
     
         52 . The apparatus of  claim 51 , wherein the failover tree construction circuitry uses a marking scheme to identify the candidate node. 
     
     
         53 . The apparatus of  claim 51 , wherein the failover tree construction circuitry constructs the shortest-path spanning tree from the candidate node to the at least one backup end-system based upon topology information obtained from a routing protocol. 
     
     
         54 . Apparatus for managing alternate site switching in a service provider network which interconnects portions of a user network, the user network including a protected end-system, a primary end-system, and at least one backup end-system coupled by the service provider network, comprising:
 a node which constructs a failover tree from the protected end-system to the at least one backup end-system including at least one service provider node and, in response to a detected condition in the user network, switches traffic from the primary end-system to a backup end-system, including sending a release message upstream toward a root node of the failover tree.   
     
     
         55 . The apparatus of  claim 54 , wherein the protected end-system is operably coupled to send a setup request message to a service provider optical edge node indicating the at least one backup end-system. 
     
     
         56 . The apparatus of  claim 55 , wherein the optical edge node corresponding to the protected end-system is operably coupled to automatically discover the at least one backup end-system using a predetermined auto-discovery mechanism. 
     
     
         57 . The apparatus of  claim 55 , wherein the optical edge node corresponding to the protected end-system is operably coupled to construct the failover tree to the backup end-system. 
     
     
         58 . The apparatus of  claim 57 , wherein the optical edge node corresponding to the protected end-system is operably coupled to determine a root node for the failover tree and construct the failover tree rooted at the root node. 
     
     
         59 . The apparatus of  claim 58 , wherein the optical edge node corresponding to the protected end-system is operably coupled to determine a root node for the failover tree by identifying a candidate node that is within a predetermined distance from the at least one backup end-system, constructing a shortest-path spanning tree from the candidate node to the at least one backup end-system, and selecting the candidate node as the root node if and only if the shortest-path spanning tree does not include any link from the protected end-system to the candidate node. 
     
     
         60 . The apparatus of  claim 58 , wherein the optical edge node corresponding to the protected end-system is operably coupled to send a setup request message specifying a failover tree structure to various nodes in the optical communication network. 
     
     
         61 . The apparatus of  claim 60 , wherein nodes associated with a primary lightpath to the primary end-system are operably coupled to reserve appropriate lightpath resources for the primary lightpath to the primary end-system. 
     
     
         62 . The apparatus of  claim 60 , wherein nodes associated with the failover tree are operably coupled to record the failover tree structure. 
     
     
         63 . The apparatus of  claim 54 , wherein the optical edge node associated with the primary end-system is operably coupled to detect a degradation or failure affecting the primary end-system by at least one of:
 monitoring a bearer channel between the primary end-system and a corresponding edge node in the optical communication network; and   querying the primary end-system by an optical service agent in said corresponding edge node.   
     
     
         64 . The apparatus of  claim 58 , wherein a failover node of the failover tree is operably coupled to establish a backup lightpath from the failover node to a backup end-system and switch traffic to the backup lightpath by the failover node upon receiving the release message. 
     
     
         65 . The apparatus of  claim 64 , wherein the failover node is operably coupled to send a lightpath setup request message downstream toward the backup end-system in order to establish a backup lightpath. 
     
     
         66 . The apparatus of  claim 65 , wherein a number of nodes between the failover node and the backup end-system are operably coupled to reserve appropriate lightpath resources for the backup lightpath. 
     
     
         67 . The apparatus of  claim 65 , wherein the failover node is operably coupled to switch traffic to the backup lightpath upon receiving a connect message from the optical edge node associated-with the backup end-system.