Communications network with routing tables for establishing a path without failure by avoiding unreachable nodes
First Claim
1. A communications network comprising:
- a plurality of network nodes interconnected by communication links, said network nodes being organized into a plurality of groups corresponding to geographic domains, ones of said network nodes located at a periphery of the network functioning as edge nodes to which user terminals are connected;
a plurality of domain connectivity tables respectively associated with said domains, each of the domain connectivity tables indicating an unavailability of intra-domain connectivity of the associated domain; and
a plurality of domain routing tables respectively associated with said domains, each of the domain routing tables indicating a route specifying ones of said network nodes whose intra-domain connectivity is indicated in the domain connectivity table of the associated domain, the routing table of each of the associated domains including a plurality of parallel routes between said source and destination terminals, each of said plurality of parallel routes repeatedly passing through the associated domain,said network nodes using said plurality of routing tables for establishing a path between said edge nodes in response to a path setup request from said user terminals by selecting one of said parallel routes having a smallest number of transit domains and discarding the parallel routes other than the selected route from the routing table.
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Abstract
In a communications network where cross-connect nodes are organized according to geographic domains, a domain connectivity table indicates intra-domain connectivity of each domain and a domain routing table indicates a route specifying those nodes whose intra-domain connectivity is indicated in the domain connectivity table. Each node uses its domain routing table to establish a path between edge nodes. In another embodiment, the domain routing table indicates routes containing no intra-domain virtual link that terminates at an edge node and no consecutively concatenated intra-domain virtual links. A backbone routing table indicates inter-domain routes and unreachability indications between border nodes of each domain and border nodes of every other domain. The inter-domain routes contain at least one of the inter-domain physical links but contain no consecutively concatenated intra-domain virtual links.
22 Citations
34 Claims
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1. A communications network comprising:
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a plurality of network nodes interconnected by communication links, said network nodes being organized into a plurality of groups corresponding to geographic domains, ones of said network nodes located at a periphery of the network functioning as edge nodes to which user terminals are connected; a plurality of domain connectivity tables respectively associated with said domains, each of the domain connectivity tables indicating an unavailability of intra-domain connectivity of the associated domain; and a plurality of domain routing tables respectively associated with said domains, each of the domain routing tables indicating a route specifying ones of said network nodes whose intra-domain connectivity is indicated in the domain connectivity table of the associated domain, the routing table of each of the associated domains including a plurality of parallel routes between said source and destination terminals, each of said plurality of parallel routes repeatedly passing through the associated domain, said network nodes using said plurality of routing tables for establishing a path between said edge nodes in response to a path setup request from said user terminals by selecting one of said parallel routes having a smallest number of transit domains and discarding the parallel routes other than the selected route from the routing table. - View Dependent Claims (2, 3, 4, 5, 6, 7, 32)
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8. A cross-connect node for a communications network in which said node comprises one of a plurality of network nodes, said network nodes being organized into a plurality of groups corresponding to geographic domains, ones of said network nodes located at a periphery of the network functioning as edge nodes to which user terminals are connected, said cross-connect node comprising:
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a domain connectivity table for indicating an unavailability of an intra-domain connectivity of the domain of said cross-connect node; a domain routing table for indicating a route specifying ones of said network nodes whose intra-domain connectivity is indicated in said domain connectivity table, the domain routing table including a plurality of parallel routes between said source and destination terminals, each of said plurality of parallel routes repeatedly passing through the domain of the cross-connect node; and a processor for using said domain routing table for establishing a path between said edge nodes in response to a path setup request from said user terminals by selecting one of said parallel routes having a smallest number of transit domains and discarding the parallel routes other than the selected route from the routing table. - View Dependent Claims (9, 10, 11, 12, 33)
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13. An operating method for a communications network, wherein the network comprises a plurality of network nodes being organized into a plurality of groups corresponding to geographic domains, ones of said network nodes located at a periphery of the network functioning as edge nodes and a plurality of user terminals connected to said edge nodes, the method comprising:
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creating a domain connectivity table for indicating an unavailability of an intra-domain connectivity of an associated one of said plurality of domains; creating a domain routing table for indicating a route specifying ones of said network nodes whose intra-domain connectivity is indicated in said domain connectivity table, the domain routing table including a plurality of parallel routes between said source and destination terminals, each of said plurality of parallel routes repeatedly passing through the domain of the cross-connect node; advertising contents of the domain routing table to the network nodes of a downstream neighbor domain; updating the domain routing table in accordance with advertised contents of the routing table of an upstream neighbor domain; and using said domain routing table for establishing a path between said edge nodes in response to a path setup request from said user terminals by selecting one of said parallel routes having a smallest number of transit domains and discarding the parallel routes other than the selected route from the domain routing table. - View Dependent Claims (14, 34)
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15. A communications network comprising:
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a plurality of network nodes organized into a plurality of groups corresponding to geographic domains, ones of said network nodes located at a periphery of the network functioning as edge nodes to which user terminals are connected, and ones of said network nodes located at border points between neighbor domains of said plurality of domains functioning as border nodes, the border nodes of same domain being interconnected by intra-domain virtual links and the border nodes of different domains being interconnected by inter-domain physical links; a plurality of domain routing tables respectively associated with said domains, each of the domain routing tables indicating a plurality of routes containing no intra-domain virtual link terminating at said edge nodes and no consecutively concatenated intra-domain virtual links, each of the domain routing tables including a plurality of parallel routes between said source and destination terminals, each of said plurality of parallel routes repeatedly passing through the associated domain; and a backbone routing table for indicating a plurality of inter-domain routes and unreachability indications between the border nodes of each domain and the border nodes of every other domain, said inter-domain routes containing at least one of said inter-domain physical links but containing no consecutively concatenated intra-domain virtual links, said network nodes using said domain routing tables and said backbone routing table for establishing a path between said edge nodes in response to a path setup request from said user terminals by selecting one of said parallel routes having a smallest number of transit domains and discarding the parallel routes other than the selected route from the domain routing table. - View Dependent Claims (16, 17, 18, 19, 20)
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21. A cross-connect node for a communications network in which said node comprises one of a plurality of network nodes, said network nodes being organized into a plurality of groups corresponding to geographic domains, ones of said network nodes located at a periphery of the network functioning as edge nodes to which user terminals are connected, and ones of said network nodes located at border points between neighbor domains of said plurality of domains functioning as border nodes, the border nodes of a same domain being interconnected by intra-domain virtual links and the border nodes of different domains being interconnected by inter-domain physical links;
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a domain routing table for indicating a plurality of routes containing no intra-domain virtual link terminating at said edge nodes and no consecutively concatenated intra-domain virtual links, the domain routing table including a plurality of parallel routes between said source and destination terminals, each of said plurality of parallel routes repeatedly passing through the associated domain; a backbone routing table for indicating a plurality of inter-domain routes and unreachability indications between the border nodes of each domain and the border nodes of every other domain, said inter-domain routes containing at least one of the inter-domain physical links but containing no consecutively concatenated intra-domain virtual links; and a processor for using said domain routing table and said backbone muting table for establishing a path between said edge nodes in response to a path setup request from said user terminals by selecting one of said parallel routes having a smallest number of transit domains and discarding the parallel routes other than the selected route from the domain routing table. - View Dependent Claims (22, 23, 24, 25, 26)
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27. An operating method for a communications network which comprises a plurality of network nodes organized into a plurality of groups corresponding to geographic domains, ones of said network nodes located at a periphery of the network functioning as edge nodes to which user terminals are connected, and ones of said network nodes located at border points between neighbor domains of said plurality of domains functioning as border nodes, the border nodes of a same domain being interconnected by intra-domain virtual links and the border nodes of different domains being interconnected by inter-domain physical links, the method comprising:
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creating a plurality of domain routing tables respectively associated with said domains, each of the domain routing tables indicating a plurality of routes containing no intra-domain virtual link terminating at said edge nodes and no consecutively concatenated intra-domain virtual links, each of said domain routing tables including a plurality of parallel routes between said source and destination terminals, each of said plurality of parallel routes repeatedly passing through the associated domain; creating a backbone routing table for indicating a plurality of inter-domain routes and unreachability indications between the border nodes of each domain and the border nodes of every other domain, said inter-domain routes containing at least one inter-domain physical link but containing no consecutively concatenated intra-domain virtual links; and using said domain routing tables and said backbone routing table for establishing a path between said edge nodes in response to a path setup request from said user terminals by selecting one of said parallel routes having a smallest number of transit domains, and discarding the parallel routes other than the selected route from the domain routing table. - View Dependent Claims (28, 29, 30, 31)
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Specification