Communication network and method which respond to a failed link

Claim 3

A method as claimed in claim 1, wherein the generating step includes the step of configuring the revised routes to divert communications away from the failed link.

Claim 4

A method as claimed in claim 1, further comprising the steps of: the one switching node terminating the failed link and operational links; and routing communications received at the one switching node for delivery over the failed routes to a selected one of the operational links, the selected operational link not being a link from which the communications were received at the one switching node.

Claim 5

A method as claimed in claim 1, wherein the generating step comprises the step of refraining from altering routes which are not failed routes.

Claim 6

A method as claimed in claim 1, wherein the generating step comprises the step of determining, for each of the failed routes, a shortest path which does not include the failed link, the shortest paths serving as the revised routes.

Claim 9

A method as claimed in claim 6, further comprising the step of generating, from time to time at the route-determining node, a series of updated routes for each switching node in the network.

Claim 10

In a network which delivers communications and which has a multiplicity of links each of which terminate at pairs of switching nodes, a method of responding to a failed link comprising the steps of: detecting the failed link at one of the switching nodes which terminates the failed link; reporting the failed link to a route-determining node; temporarily diverting, at the one switching node, communications being delivered over routes which include the failed link to a link other than the failed link; identifying, at the route-determining node, failed routes resulting from the failed link, the failed routes defining a set of paths each of which includes the failed link and each of which is used to route communications through the switching nodes; generating, at the route-determining node, a set of revised routes to replace the failed routes, the revised routes being associated with a future epoch; sending, prior to the future epoch and after the diverting step, data describing the revised routes from the route-determining node to the switching nodes; and operating the switching nodes substantially at the future epoch in response to the revised routes.

Claim 11

In a network which delivers communications and which has a multiplicity of links each of which terminate at pairs of switching nodes, a method of responding to a failed link comprising the steps of: detecting the failed link at one of the switching nodes which terminates the failed link; reporting the failed link to a route-determining node; temporarily diverting, at the one switching node, communications being delivered over routes which include the failed link to a link other than the failed link; identifying, at the route-determining node, failed routes resulting from the failed link, the failed routes defining a set of paths each of which includes the failed link and each of which is used to route communications through the switching nodes; generating, at the route-determining node, a set of revised routes to replace the failed routes, the revised routes being associated with a future epoch; sending, prior to the future epoch and after the diverting step, data describing the revised routes from the route-determining node to the switching nodes; and operating the switching nodes substantially at the future epoch in response to the revised routes.

Claim 12

A method as claimed in claim 8 further comprising the step of: terminating the failed link and operational links at the one switching node; and routing communications received at the one switching node for delivery over the failed routes to a selected one of the operational links, the selected operational link not being a link from which the communications were received at the one switching node.

Claim 13

A method as claimed in claim 8, further comprising the steps of: repeating the generating step for each of a plurality of future epochs so that a set of revised routes is associated with each of the future epochs; sending the sets of the revised routes; and operating the switching nodes substantially at each of the plurality of future epochs in response to the sets of the revised routes.

Claim 14

A method as claimed in claim 10, further comprising the step of generating, from time to time at the route-determining node, a series of updated routes for each switching node in the network.

Claim 15

A method as claimed in claim 8, wherein the generating step comprises the step of determining, for each of the failed routes, a shortest path which does not include the failed link, the shortest paths serving as the revised routes.

Claim 16

A method as claimed in claim 12, wherein the determining step includes the step of refraining from changing routes which are not failed routes.

Claim 17

A fault-tolerant communications network, comprising: a switching node configured to detect a failed link which terminates at a node, to report the failed link using a message delivered through the network and to divert communications being delivered over routes which do not include the failed link; and a route-determining node, coupled to the switching node, configured to respond to the message by identifying failed routes which result from the failed link, the failed routes defining a set of paths each of which includes the failed link and each of which is used in delivering communications through the network, by generating a set of revised routes to replace the failed routes, and by sending after the switching node begins to divert communication data describing the revised routes to various switching nodes of the network.

Claim 18

A fault-tolerant communications network, comprising: a switching node configured to detect a failed link which terminates at a node, to report the failed link using a message delivered through the network and to divert communications being delivered over routes which do not include the failed link; and a route-determining node, coupled to the switching node, configured to respond to the message by identifying failed routes which result from the failed link, the failed routes defining a set of paths each of which includes the failed link and each of which is used in delivering communications through the network, by generating a set of revised routes to replace the failed routes, and by sending after the switching node begins to divert communication data describing the revised routes to various switching nodes of the network.

Claim 19

A network as claimed in claim 14, wherein the route-determining node is configured so that the revised routes divert communications away from the failed link.

Claim 20

A network as claimed in claim 14, wherein the route-determining node is configured to associate the revised routes with a future epoch and to send data describing the revised routes prior to the future epoch.

Claim 21

A network as claimed in claim 14, wherein the route-determining node is configured to refrain from altering routes which are not failed routes while generating the set of revised routes.

Claim 22

A network as claimed in claim 14, wherein the route-determining node is configured to determine, for each of the failed routes, a shortest path which does not include the failed link, the shortest paths serving as the revised routes.

Claim 27

A fault-tolerant communications network comprising: a switching node configured to detect a failed link, to report the failed link using a message delivered through the network and to divert communications being delivered over routes which do not include the failed link; and a route-determining node, coupled to the switching node, configured to respond to the message by generating a set of revised routes associated with each of a plurality of future epochs to replace the failed routes and by sending data describing the sets of revised routes to various switching nodes of the network.

Claim 28

A fault-tolerant communications network comprising: a switching node configured to detect a failed link, to report the failed link using a message delivered through the network and to divert communications being delivered over routes which do not include the failed link; and a route-determining node, coupled to the switching node, configured to respond to the message by generating a set of revised routes associated with each of a plurality of future epochs to replace the failed routes and by sending data describing the sets of revised routes to various switching nodes of the network.

Claim 29

A fault-tolerant communications network comprising: a switching node configured to detect a failed link, to report the failed link using a message delivered through the network and to divert communications being delivered over routes which do not include the failed link; and a route-determining node, coupled to the switching node, configured to respond to the message by generating a set of revised routes to replace the failed routes and by sending after the switching node begins to divert the communications data describing the revised routes to various switching nodes of the network.

Claim 30

A fault-tolerant communications network comprising: a switching node configured to detect a failed link, to report the failed link using a message delivered through the network and to divert communications being delivered over routes which do not include the failed link; and a route-determining node, coupled to the switching node, configured to respond to the message by generating a set of revised routes to replace the failed routes and by sending after the switching node begins to divert the communications data describing the revised routes to various switching nodes of the network.