Distributed protocol for improving the survivability of telecommunications trunk networks
First Claim
1. A method for reconfiguring a telecommunications network comprising a plurality of reconfigurable cross-connect nodes interconnected by links when a failure event occurs, said method comprising the steps ofstoring at each node a precomputed configuration table corresponding to each of a plurality of possible network topologies which result from a plurality of possible failure events,after a specific failure event occurs, flooding the network with messages by sending from node to node messages of the specific failure event generated by the node detecting the specific failure event so that each of the nodes is informed as to the specific existing topology of the network which results from the specific failure event and such that the network nodes converge to a consistent and correct picture of the existing network topology, andreconfiguring the nodes in accordance with the specific precomputed configuration tables which correspond to the specific existing network topology, wherein reconfiguration of the telecommunication network is accomplished without the use of a separate central network controller.
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Abstract
A method for reconfiguring a telecommunications network comprising a plurality of reconfigurable cross-connect nodes interconnected by links when a failure event occurs is disclosed. The method comprises storing at each node a precomputed configuration table corresponding to each of a plurality of possible network topologies which can result from a plurality of possible failure events. After a specific failure event occurs, the network is flooded with messages so that each of the nodes is informed as to the specific existing topology of the network resulting from the specific failure event. The nodes are then reconfigurated in accordance with the precomputed configuration tables which correspond to the specific existing network topology.
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Citations
14 Claims
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1. A method for reconfiguring a telecommunications network comprising a plurality of reconfigurable cross-connect nodes interconnected by links when a failure event occurs, said method comprising the steps of
storing at each node a precomputed configuration table corresponding to each of a plurality of possible network topologies which result from a plurality of possible failure events, after a specific failure event occurs, flooding the network with messages by sending from node to node messages of the specific failure event generated by the node detecting the specific failure event so that each of the nodes is informed as to the specific existing topology of the network which results from the specific failure event and such that the network nodes converge to a consistent and correct picture of the existing network topology, and reconfiguring the nodes in accordance with the specific precomputed configuration tables which correspond to the specific existing network topology, wherein reconfiguration of the telecommunication network is accomplished without the use of a separate central network controller.
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9. A protocol carried out at each node in a network comprising a plurality of reconfigurable cross-connect nodes interconnected by links to reconfigure the network in the event of a failure event, said protocol comprising the steps of:
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at each node, maintaining an array indicating the status of all of the links in the network, at each node, storing a plurality of predetermined configuration tables corresponding to a plurality of possible patterns of non-working links, at each node, sequentially testing all of the links associated with the node which are indicated by the array to be working, if a specific link is determined as a result of the testing step to be non-working, updating the array, sending a message on all links associated with the node indicating that the specific link is non-working, and reconfiguring the node in accordance with the predetermined configuration table corresponding to the pattern of non-working links indicated by the updated array if the node is not already in this configuration, if a specific link is determined as a result of the testing step to be working, determining if a message has been received via the specific link indicating that another link in the network is non-working and, if a message has been received via the specific link indicating that another link in the network is non-working and the array does not already indicate that the other link is non-working, updating the array, sending a message on all links associated with the node indicating that the other link is non-working, and reconfiguring the node in accordance with the predetermined configuration table corresponding to the pattern of non-working links indicated by the updated array if the node is not already in this configuration.
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10. A protocol carried out continuously at each node in a network comprising a plurality of reconfigurable cross-connect nodes interconnected by links, said protocol comprising the steps of
(a) at each node, sequentially testing all of the links associated with the node which are indicated by a link status array to be working, (b) if a specific link is determined as a result of said testing step to be non-working, updating the link status array, sending a message on the working links associated with the node that the specific link is non-working, and reconfiguring the node in accordance with a prestored configuration table corresponding to the particular pattern of non-working links indicated by the updated link status array, and (c) if a specific link is determined as a result of the testing step to be working and a message has been received via the specific link indicating that another link in the network is non-working and the link status array does not already indicate that the other link is non-working, sending a message on the working links associated with the node indicating that the other link is non-working, updating the link status array at the node, and reconfiguring the node in accordance with a prestored configuration table corresponding to the particular pattern of non-working links indicated by the updated link status array.
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11. A method of reconfiguring a telecommunications network to maintain a set of logical connections defined in said network in the event of a failure of a component in said network, said method comprising
storing at each node in said network a precomputed configuration table corresponding to each of a plurality of possible network component failures, after a specific failure of one or more network components, flooding the network with messages by sending from node to node messages of the failure events generated by the nodes detecting the specific failure events so that each of the nodes is informed of the specific failure and the network nodes converge to a consistent and correct picture of the existing network topology, and reconfiguring the nodes in accordance with the specific precomputed configuration tables corresponding to the specific failure to maintain said set of logical connections.
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14. A method for reconfiguring a telecommunications network comprising a plurality of reconfigurable cross-connect nodes interconnected by links when a failure event occurs, said method comprising the step of
storing at each node a precomputed configuration table corresponding to each of a plurality of possible network topologies which result from a plurality of possible failure events, after a specific failure event occurs, detecting the specific failure event at a node, generating messages of the failure event from the node detecting the failure event over the links associated with said detecting node to other nodes connected to said detecting node by associated links, sending from node to node the messages generated in said generating step such that the network nodes converge to a consistent and correct picture of the existing network topology, and reconfiguring the nodes in accordance with the specific precomputed configuration tables which correspond to the specific existing network topology.
Specification