Abstract: To revert the topology of a network to its original or normal state after an alternate route has been found for bypassing traffic away from a malfunctioned link that has since been repaired, an Operation Support System (OSS) sends to each of the custodial sender/chooser nodes and the tandem nodes that form the alternate route respective commands to revert the operation(s) that each node had performed during distributed restoration. The OSS is able to identify the custodial nodes by the fact that those nodes perform more operations than the tandem nodes. The operations that were performed during the distributed restoration process were recorded and the thus restored topology of the network is mapped and stored. Upon receipt from the different nodes that the malfunctioned link has been repaired, the OSS sends to each of the nodes a specific command to perform the inverse of the operation(s) that that node had performed during the restoration.

Abstract: To verify that a communications path restored in response to a failure to a telecommunications network is a validly restored path, each of the end nodes terminating the restored communications path sends out a message containing data that identifies that node and the ID of the access/egress port to which the STS-1 circuit forming the communications path is connected. Once the respective path verification messages are exchanged between the two end nodes of the communications path, the Operations Support System (OSS) that oversees the topology of the network retrieves those messages and compares the data contained therein with the data of the same type of messages from the same ends nodes that were stored just prior to the occurrence of the disruption to the communications path. The restored communications path is deemed to be verified if there are no differences between the path verification messages retrieved after the failure event and the path verification messages stored just prior to the failure event.

Abstract: To estimate an optimal amount of spare capacity for a network so that efficient distributed restoration of the network can take place in the event of a network failure, parameter assumptions and network design guidelines are provided to a network modeling tool to generate a desirable amount of spare links for the network. The spare links are allocated to the different nodes of the network. After a failure in the network, the result of the restoration of the network due to the failure is reported to the controller of the system. If necessary, the parameter assumptions and network design guidelines are updated and fed back to the network modeling tool for further refining the spare capacity of the network. An optimal amount of spare capacity is thus achieved by a continuous redeployment of the spare capacity output provided by the network modeling tool. Simulated failures and subsequent restorations of the network are provided to an exerciser periodically.

Abstract: The present invention provides to a distributed restoration scheme a set of timers so that multiple senders and choosers can more fairly contend for the spare capacity of a telecommunications network. In particular, a preactivation timer would force a sender that had reserved excess spare capacity of the network for restoring its own failed links to release any unused spare capacity prior to the time that it terminates its operation, provided that it has found an alt-route or alt-routes for its failed link. An alarm validation timer and a hold off timer in the invention scheme further provide for respective validation and detection that a detected fault is not transient or intermittent in nature and that a restoration process is needed to find the alt-routes.