Reliable connection oriented networks
First Claim
1. In a connection oriented network for carrying communications over connections, a method of protecting a plurality of connections against the occurrence of one of a plurality of anticipated failure conditions comprising the steps of:
- providing all nodes in the network with a common definition of the anticipated failure conditions;
providing for a plurality of links of said network a reserve capacity of bandwidth not to be used for normal connection establishment;
following the establishment of a protected connection, selecting a contingent path for the established protected connection for each anticipated failure condition which affects the protected connection, without using more than residual reserve capacity available for that failure condition on each link of said contingent path;
for each link, for each anticipated failure condition, maintaining a record of reserve capacity allocated for contingent paths of the anticipated failure condition over said link for said plurality of protected connections; and
responsive to detection of one of said anticipated failure conditions and failure of one of said protected circuits, establishing a connection corresponding to the selected contingent path for said one of said anticipated failure conditions and the failed one of said protected circuits.
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0 Petitions
Accused Products
Abstract
When protected network connections on a connection oriented network are disrupted because a network resource fails (e.g. the severing of a fiber cable upon which multiple links are multiplexed), they must be rerouted around the network failure. This invention expedites this rerouting and permits it to be carried out in a distributed manner similar to conventional routing. Advantageously, the amount of link bandwidth reserved for rerouting of failed connections is reduced relative to conventional methods.
For each protected connection, for each anticipated failure condition, a "contingent path" is selected shortly after the connection is established. This contingent path is then used to reroute that connection in the event of the occurrence of that failure condition. To the extent that only one of the anticipated for network failures occurs at a time (possibly affecting many links, and all connections using those links), the corresponding set of activated contingent paths will all fit within the reserved bandwidth of each link. This follows from the rules used in the prior selection of the contingent paths whereby link reserved bandwidth is allocated to contingent paths on the basis of anticipated failure conditions. Advantageously, in case of a network failure, most or all protected connections can be re-established on the first try.
200 Citations
8 Claims
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1. In a connection oriented network for carrying communications over connections, a method of protecting a plurality of connections against the occurrence of one of a plurality of anticipated failure conditions comprising the steps of:
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providing all nodes in the network with a common definition of the anticipated failure conditions; providing for a plurality of links of said network a reserve capacity of bandwidth not to be used for normal connection establishment; following the establishment of a protected connection, selecting a contingent path for the established protected connection for each anticipated failure condition which affects the protected connection, without using more than residual reserve capacity available for that failure condition on each link of said contingent path; for each link, for each anticipated failure condition, maintaining a record of reserve capacity allocated for contingent paths of the anticipated failure condition over said link for said plurality of protected connections; and responsive to detection of one of said anticipated failure conditions and failure of one of said protected circuits, establishing a connection corresponding to the selected contingent path for said one of said anticipated failure conditions and the failed one of said protected circuits. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. In a connection oriented network, comprising a plurality of nodes, for carrying communications over connections, a node of said networks comprising:
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terminations for links for connecting said node to other nodes of said network; a switching network fabric for switching communications between said links; and processor means comprising memory means for controlling said switching network fabric for establishing communications connections between ones of said links; said processor means operative under control of a program stored in said memory means for; initializing tables in said memory means, said tables comprising data based on a common definition of a plurality of anticipated failure conditions, and for providing a reserve capacity of bandwidth not to be used for normal connection establishment for links under the control of said node; controlling establishment of a protected connection; controlling selection of a contingent path for the established protected connection for each of said anticipated failure conditions which affect said protected connection, without using more than a residual reserve capacity available for that failure condition on each link of said contingent path; for each link owned by said node, for each anticipated failure condition, maintaining a record of reserve capacity allocated for contingent paths of the anticipated failure condition over said link; and responsive to detection of one of said anticipated failure conditions, and failure of said protected connection, controlling establishment of a connection corresponding to the selected contingent path for the failed protected circuit.
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Specification