Agile digital communication network with rapid rerouting
First Claim
1. A digital storage system comprising:
- (a) a digital storage facility;
(b) a mesh network of routers connected to the digital storage facility;
(c) a plurality of access points to the network for connection to a plurality of user computers;
(d) each router in the network having a plurality of links connected between it and a neighboring router;
(e) the network operating on an open shortest path first protocol;
(f) each router being programmed for;
(i) calculating the shortest path to other routers starting with a first hop to a neighboring router along one of the links connecting to a neighboring router;
(ii) storing at least each shortest first path hop of each calculated shortest path;
(iii) calculating alternate paths to other routers, which alternate paths have a first hop on another of the links connecting to a further neighboring router;
(iv) storing the calculated alternate paths;
(v) detecting whether links connected to the router are operable;
(vi) for a limited time interval following detection of a link becoming inoperable, employing a previously calculated one of the alternate paths for communications to those routers for which the first hop on the calculated shortest path was along the now-inoperable link.
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Accused Products
Abstract
An agile digital communications network has a number of routers that serve as nodes in a mesh network communicating between a user device (e.g., computer, server, etc.) and a target device (e.g., disc storage cabinets, tape, jukebox, etc.). The routers operate on an open shortest path first protocol, each router having two or more interfaces or links to other routers. When a link connected to a router is down and is in the shortest path to another router identified in a communication packet, the packet is forwarded to the identified router on a precalculated alternate route that does not use the unavailable link. IP tunneling assures that routing loops do not occur and send the packet back to the router with the unavailable link because it would have been in the shortest path of an intermediate router. A tunneling technique is provided that maximizes the levels of encapsulation needed at two, regardless of the size or configuration of the network. An unavailable link is not broadcast immediately throughout the network, giving the link an opportunity to be restored before all of the routers are called on to recalculate the shortest paths and alternate paths. During a short interval following the discovery of an unavailable link, then, a router connected to that link is in a state identified as the Use Alternate Path state, and the link is repeatedly checked for availability. Each router calculates and stores the alternative paths to each other router after first calculating the shortest path to each other router. The alternate paths are pulled up and used when an unavailable link is detected. Dijkstra'"'"'s algorithm is used to calculate the shortest paths. A new algorithm called the iterative dynamic Dijkstra'"'"'s algorithm is used to calculate the alternative routes.
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Citations
25 Claims
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1. A digital storage system comprising:
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(a) a digital storage facility; (b) a mesh network of routers connected to the digital storage facility; (c) a plurality of access points to the network for connection to a plurality of user computers; (d) each router in the network having a plurality of links connected between it and a neighboring router; (e) the network operating on an open shortest path first protocol; (f) each router being programmed for; (i) calculating the shortest path to other routers starting with a first hop to a neighboring router along one of the links connecting to a neighboring router; (ii) storing at least each shortest first path hop of each calculated shortest path; (iii) calculating alternate paths to other routers, which alternate paths have a first hop on another of the links connecting to a further neighboring router; (iv) storing the calculated alternate paths; (v) detecting whether links connected to the router are operable; (vi) for a limited time interval following detection of a link becoming inoperable, employing a previously calculated one of the alternate paths for communications to those routers for which the first hop on the calculated shortest path was along the now-inoperable link. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of communicating between at least one initiator and at least one target comprising:
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(a) providing a mesh network of routers connected to a digital storage facility; (b) providing a plurality of access points to the network for connection to one or more initiators and one or more targets; (c) providing each router in the network with a plurality of links connected between it and neighboring routers; (d) operating the network on an open shortest path first protocol; (e) for each router; (i) calculating the shortest path to other routers starting with a first hop to a neighboring router along one of the links connecting to a neighboring router; (ii) storing at least each shortest first path hop of each calculated shortest path; (iii) calculating alternate paths to other routers, which alternate paths have a first hop on another of the links connecting to a further neighboring router; (iv) storing the calculated alternate paths; (v) detecting whether links connected to the router are operable; (vi) for a limited time interval following detection of a link becoming inoperable, employing a previously calculated one of the alternate paths for communications to those routers for which the first hop on the calculated shortest path was along the now-inoperable link. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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Specification