System and method of fault restoration in communication networks
OwnerThomas E. Stern, Aklilu Hailemariaminventors
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Abstract
A method and system is described for the restoration of communications in a communication network upon the detection of a perceived fault. The system is able to restore a fault without the node detecting a perceived link fault knowing whether the actual fault is on the link or the node attached to the other end of the link. Upon fault detection, the system reroutes communications affected by the fault onto predefined restoration paths by reconfiguring the cross-connects in the network nodes. Each restoration path is restricted to an island which is a prescribed sub-network made up of nodes and links surrounding the fault.
Claims30
A system for communication restoration in a communication network upon detection of a perceived fault, the system comprising:
- a plurality of communication nodes, each node being connected to at least one other node by a communication link;
- a plurality of communication links, each link supporting at least one channel in each direction, the channel supported by a transmission facility in each direction on the link;
- a plurality of communication devices of which at least two of the devices are connected to or incorporated in respective nodes;
- at least one node acting as a source of a communication connection for the device associated with the node, and at least one node acting as a destination of a communication connection for the device associated with the node;
- at least two of the nodes containing controllable cross-connects, the cross-connects having at least two input ports and two output ports, the channels on the node's incident links connected to the input ports and the output ports of the cross-connects;
- at least two of the nodes containing restoration subsystems for restoring communication connections upon perceived link failure;
- at least one node triggers a fault restoration procedure once that node detects the perceived link failure;
- wherein the subsystem for restoring communication connections:
- (1) detects perceived faults on the links attached to its nodes, (2) stores information related to fault restoration, and (3) exchanges information between nodes for executing fault restoration procedures, and
- wherein the fault restoration procedures:
- (1) reconfigure the controllable cross-connects to detour communication connections affected by the perceived fault using predetermined restoration paths on links confined to a prescribed island associated with each perceived fault, the island being a prescribed sub-network of the communication network containing the perceived fault and (2) restore communication connections carried by the link perceived to have failed without the restoration subsystem in the node detecting the perceived link fault requiring knowledge of whether an actual fault is on the link or the node connected to the other end of the link.
A method for communication restoration upon detection of a perceived fault in a communication network having a plurality of communication nodes, each node being connected to at least one other node by a communication link, at least two communication nodes contain a system for detecting perceived faults on communication links attached to the communication nodes, for storing information related to fault restoration, and for exchanging information between nodes for executing fault restoration procedures;
- a plurality of communication links, each link supporting at least one communication channel in each direction, the communication channel supported by a transmission facility in each direction on the link;
- and a plurality of communication devices of which at least one device is connected to or incorporated in a node, behaving as a source of a communication connection and at least one device is connected to or incorporated in a node, behaving as a destination of a communication connection;
- wherein at least two nodes contain a controllable cross-connect with at least two input ports and two output ports, the communication channels connecting to the input ports and the output ports of the controllable cross-connects, comprising the steps of:
- pre-determining restoration paths on links confined to a prescribed island for each perceived link fault;
- triggering fault restoration once at least one node detects the perceived link fault;
- re-configuring cross-connects to detour communication connections affected by the perceived link fault along the predetermined restoration paths confined to the prescribed island of the perceived link fault;
- and,
- restoring some or all communication connections carried by the link perceived to have failed, without the node detecting the perceived link fault having knowledge of whether an actual fault is on the link or the node attached to the other end of the link.
A method for fault restoration of a communication connection upon detection of a perceived fault in a communication network having a set of nodes, at least one node being a source node for a communication connection and at least one node being a destination node for a communication connection, at least two nodes containing a controllable cross-connect and a set of links connecting the nodes, comprising the steps of:
- identifying islands of nodes and links surrounding a node, an island node, where communication connections designated for restoration in that island upon perceived fault detection, are restored on restoration paths confined to the island surrounding the island node,
- storing in routing tables in the nodes participating in restoration of the perceived fault, a restoration subsystem necessary to restore each communication connection disrupted by the perceived fault on a predetermined restoration path, each restoration path having required capacity to support the restored communication connection;
- reserving the required capacity on each link for each predetermined restoration path using that link in the event of an actual fault;
- and,
- restoring a communication connection upon detection of a perceived link fault by reconfiguring the cross-connects according to the stored routing tables wherein the restoring step reconfigures without the system in a node detecting the perceived link fault having knowledge of whether the actual fault is on the link or the node attached to the other end of the link.
Dependencies are inferred from the claim text.