Distributed connection establishment and restoration

Abstract

Connection constraints are flooded using an extension to a routing protocol being used to control forwarding on network. Nodes maintain topology and connection database and calculate routes for connections based on the constraints. If a node is on a calculated route for a connection it will install forwarding state for the connection. Since each node has a consistent view of the network topology and has been provided with the constraints associated with the connection, each node on the network will calculate the same route for the connection. When a failure occurs, the nodes will calculate restoration paths for the connections on a network-wide priority basis to enable restoration paths to be created for the affected connections without requiring the restoration paths to be signaled. Time-stamps are used to allow events to be applied by nodes in a consistent order regardless of the order in which they arrive.

What is claimed is: 
     
         1 . A link state protocol controlled network comprising a plurality of interconnected nodes, the nodes being configured:
 to maintain consistent views of a topology of the network;   when establishing a new connection, to advertise constraints associated with the new connection to other nodes of the network;   when another node is establishing the new connection, to receive the constraints associated with the new connection advertised by the other node;   to calculate a route for the new connection based on the constraints; and   to install a forwarding state for the new connection only when the node is on the route calculated for the new connection.   
     
     
         2 . The network of  claim 1 , wherein the network is a link state protocol controlled Ethernet network. 
     
     
         3 . The network of  claim 1 , wherein the nodes are configured to maintain a connection database containing entries defining at least one connection established on the network and a respective route for each at least one connection established on the network. 
     
     
         4 . The network of  claim 1 , wherein the constraints for the new connection identify at least a head-end node on the network, a destination node on the network, an indication of the bandwidth associated with the new connection, and a priority indication for the new connection. 
     
     
         5 . The network of  claim 4 , wherein the nodes are configured to calculate routes for connections in priority order. 
     
     
         6 . The network of  claim 1 , wherein the nodes are configured to maintain current views of the network topology having a first timestamp, an earlier view of the network topology having a second timestamp, and lists of time-stamped events that have occurred between a time associated with the second timestamp and a time associated with the first timestamp. 
     
     
         7 . The network of  claim 6 , wherein the nodes are configured to receive event notifications. 
     
     
         8 . The network of  claim 7 , wherein:
 the event notifications include respective timestamps; and   the nodes are configured to compare timestamps of event notifications with timestamps associated with current views of the network topology.   
     
     
         9 . The network of  claim 8 , wherein the nodes are configured to apply received event notifications to the current view of the network topology when the timestamp of the event notification is after the timestamp associated with the current view of the network topology. 
     
     
         10 . The network of  claim 8 , wherein the nodes are configured:
 to revert to the earlier view of the network topology when the timestamp of the event notification is before the timestamp associated with the current view of the network topology; and   to re-apply events from the list of time-stamped events along with the event notification.   
     
     
         11 . The network of  claim 7 , wherein at least one event notification relates to addition of a node to the network. 
     
     
         12 . The network of  claim 7 , wherein at least one event notification relates to addition of a link to the network. 
     
     
         13 . The network of  claim 7 , wherein at least one event notification relates to deletion of a node from the network. 
     
     
         14 . The network of  claim 7 , wherein at least one event notification relates to deletion of a link from the network. 
     
     
         15 . The network of  claim 7 , wherein at least one event notification relates to addition of a connection to the network. 
     
     
         16 . The network of  claim 7 , wherein at least one event notification relates to deletion of a connection from the network. 
     
     
         17 . The network of  claim 7 , wherein at least one event notification relates to failure of a node on the network. 
     
     
         18 . The network of  claim 7 , wherein at least one event notification relates to failure of a link on the network. 
     
     
         19 . The network of  claim 7 , wherein at least one event notification relates to recovery of a node on the network. 
     
     
         20 . The network of  claim 7 , wherein at least one event notification relates to recovery of a link on the network.