Abstract: In a method of providing protection switching in a meshed communications network, a protection path between two nodes on the network is only established, on demand, as it is required, after a fault along a working path between the two nodes has been detected. After the protection path is established, carriage of traffic from the working path is switched to the protection path. Once the working path is restored, traffic is switched back from the protection path to the working path, and the protection path is torn down. Switching between working and protection channels may be effected using a path establishment protocol or using protection switching mechanisms of existing network protocols, such as SONET or ATM APS. Software and network nodes embodying the method are also disclosed.

Abstract: Dynamic adaptation of connection-oriented networks is introduced wherein, once congestion is encountered, dynamic adaptation steps may be performed. Four adaptation steps are proposed for reacting to various network congestion scenarios. It is further recommended that the steps are performed in a particular order such that the higher severity and longer sustentation of the network congestion the more strict step is performed to alleviate the network congestion. At a switch in the connection-oriented network, utilization of a trunk carried on a link connected to the switch is monitored and, if said utilization of said trunk exceeds a first threshold, a first degree of adaptation is initialized wherein use of the trunk by further connections is prevented. Subsequent degrees of adaptation are triggered when high utilization continues and surpasses higher thresholds. The subsequent degrees of adaptation involve rerouting connections that make use of the trunk.

Abstract: In a switching protection system, a protocol is followed by a first connection controller to help facilitate the resynchronization of the network after the failure has occurred. This protocol contains the messaging system of the ability to query and store the exact sequence of logical ports and time slots that make up the data path, as a resynchronization table coupled to the first controller. The head/ingress end of the path can receive this information during set-up and can store it both locally and in shadow locations. The system also contains the ability to distinguish between signaling and data channel failures, as signaling channel failures to do not clear cross connect data but simply leave it “ownerless”. The system also contains the ability to populate the exact sequence of logical ports and time slots accumulated in the definition of the network, as the set-up message initiated by the head controller to re-claim “ownerless” cross connections contained on respective network elements.

Abstract: A process for selecting the best possible route for an alternate communications path in connection-oriented networks takes into account the reserved network resources and the set of links and/or nodes used by a current communications path. Whenever a request for route selection includes the resources reserved by the current communications path, the alternate communications path is computed considering the network resources reserved by the current communications path as available, in addition to the available network resources existing in the topology database. In another embodiment of the invention, the topology database is initially modified such that the network resources reservations used by the current communications path are removed from the topology database. The alternate communications path is then computed. Finally, the topology database is restored to reflect again the network resources reservations used by the current communications path.

Abstract: In a method of providing protection switching in a meshed communications network, a protection path between two nodes on the network is only established, on demand, as it is required, after a fault along a working path between the two nodes has been detected. After the protection path is established, carriage of traffic from the working path is switched to the protection path. Once the working path is restored, traffic is switched back from the protection path to the working path, and the protection path is torn down. Switching between working and protection channels may be effected using a path establishment protocol or using protection switching mechanisms of existing network protocols, such as SONET or ATM APS. Software and network nodes embodying the method are also disclosed.

Abstract: In a switching protection system, a protocol is followed by a first connection controller to help facilitate the resynchronization of the network after the failure has occurred. This protocol contains the messaging system of the ability to query and store the exact sequence of logical ports and time slots that make up the data path, as a resynchronization table coupled to the first controller. The head/ingress end of the path can receive this information during set-up and can store it both locally and in shadow locations. The system also contains the ability to distinguish between signaling and data channel failures, as signaling channel failures to do not clear cross connect data but simply leave it “ownerless”.

Abstract: Dynamic adaptation of connection-oriented networks is introduced wherein, once congestion is encountered, dynamic adaptation steps may be performed. Four adaptation steps are proposed for reacting to various network congestion scenarios. It is further recommended that the steps are performed in a particular order such that the higher severity and longer sustentation of the network congestion the more strict step is performed to alleviate the network congestion. At a switch in the connection-oriented network, utilization of a trunk carried on a link connected to the switch is monitored and, if said utilization of said trunk exceeds a first threshold, a first degree of adaptation is initialized wherein use of the trunk by further connections is prevented. Subsequent degrees of adaptation are triggered when high utilization continues and surpasses higher thresholds. The subsequent degrees of adaptation involve rerouting connections that make use of the trunk.

Abstract: An alternate path can be established in a connection-oriented packet switching network by correlating the bandwidth reservation of this alternate path with the bandwidth reservation of an active path on trunks through which both paths pass. The alternate path that is established can have one or more of a number of different attributes that vary from the attributes of the active path. The alternate path is established in a connection-oriented network with bandwidth correlation in three stages: a keying stage, a correlation stage and, a transfer stage. An alternate path may be established without a double reservation of bandwidth, thus making efficient use of limited network resources.