Restrictive costs in network systems
First Claim
1. A method of generating a set of restrictive costs associated with directional paths between selected nodes in a group of nodes of a network system wherein each of said nodes in said group of nodes is connected by a link to at least one other of said nodes in said group, and each link has a pair of directional costs associated therewith such that said link can be considered as a pair of oppositely-directed, unidirectional links each of which extends from a source node to a destination node and has a said directional cost associated therewith, the method comprising:
- (a) assigning a unique identifier to each of said selected nodes;
(b) selecting said unidirectional links in order of cost;
(c) for each of said unidirectional links selected, if a said identifier has previously been assigned to said source node for a said link and a said identifier has not previously been assigned to said destination node for a said link, assigning a said identifier to said destination node and any further nodes, which are reachable from said destination node by traversing said unidirectional links selected thus far, to which a said identifier has not previously been assigned;
(d) if said step (c) results in assignment to a said selected node of a said identifier not previously assigned to said selected node, storing said directional cost of the last-selected said unidirectional link as said restrictive cost for said directional path to said selected node from a said selected node to which said identifier was initially assigned in said step (a); and
(e) repeating said steps (b) to (d) at least until said restrictive cost has been stored for said directional paths between predetermined pairs of said selected nodes.
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Accused Products
Abstract
Methods and apparatus are provided for generating a set of restrictive costs associated with directional paths between selected nodes in a group of nodes of a network system wherein each node in the group is connected by a link to at least one other node in the group, and each link has a pair of directional costs associated therewith such that each link can be considered as a pair of oppositely-directed, unidirectional links each of which extends from a source node to a destination node and has a said directional cost associated therewith. The method allows asymmetric costs, rather than merely symmetric costs, to be considered, and can be applied, for example, to generate the transition matrix for a PNNI peer group.
56 Citations
23 Claims
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1. A method of generating a set of restrictive costs associated with directional paths between selected nodes in a group of nodes of a network system wherein each of said nodes in said group of nodes is connected by a link to at least one other of said nodes in said group, and each link has a pair of directional costs associated therewith such that said link can be considered as a pair of oppositely-directed, unidirectional links each of which extends from a source node to a destination node and has a said directional cost associated therewith, the method comprising:
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(a) assigning a unique identifier to each of said selected nodes;
(b) selecting said unidirectional links in order of cost;
(c) for each of said unidirectional links selected, if a said identifier has previously been assigned to said source node for a said link and a said identifier has not previously been assigned to said destination node for a said link, assigning a said identifier to said destination node and any further nodes, which are reachable from said destination node by traversing said unidirectional links selected thus far, to which a said identifier has not previously been assigned;
(d) if said step (c) results in assignment to a said selected node of a said identifier not previously assigned to said selected node, storing said directional cost of the last-selected said unidirectional link as said restrictive cost for said directional path to said selected node from a said selected node to which said identifier was initially assigned in said step (a); and
(e) repeating said steps (b) to (d) at least until said restrictive cost has been stored for said directional paths between predetermined pairs of said selected nodes. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of distributing topology data in a network system including a group of nodes which comprises a plurality of border nodes, each of said border nodes being connected to another of said nodes of said network system outside said group, and in which each of said nodes in said group is connected by a link to at least one other of said nodes in said group, and each of said links has a pair of directional costs associated therewith such that each of said links can be considered as a pair of oppositely-directed, unidirectional links each of which extends from a source node to a destination node and has a said directional cost associated therewith, the method comprising:
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generating a set of restrictive costs associated with directional paths between said border nodes; and
transmitting said topology data indicative of said set of restrictive costs to at least one of said nodes of said network system outside said group;
wherein said set of restrictive costs is generated by;
(a) assigning a unique identifier to each of said border nodes;
(b) selecting said unidirectional links in order of cost;
(c) for each of said unidirectional links selected, if a said identifier has previously been assigned to said source node for said link and said identifier has not previously been assigned to said destination node for said link, assigning said identifier to said destination node and any further of said nodes, which are reachable from said destination node by traversing said unidirectional links selected thus far, to which said identifier has not previously been assigned;
(d) if said step (c) results in assignment to a said border node of a said identifier not previously assigned to said border node, storing said directional cost of the last-selected of said unidirectional links as said restrictive cost for said directional path to said border node from one of said border nodes to which said identifier was initially assigned in said step (a); and
(e) repeating said steps (b) to (d) at least until said restrictive cost has been stored for said directional paths between predetermined pairs of said border nodes. - View Dependent Claims (10)
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11. A method of selecting a path for routing a call across a group of nodes in a network system wherein said group of nodes comprises a plurality of border nodes, each of said border nodes being connected to another of said nodes of said network system outside said group, each of said nodes in said group is connected by a link to at least one other of said nodes in said group, and each of said links has a pair of directional costs associated therewith such that each of said links can be considered as a pair of oppositely-directed, unidirectional links extending from a source node to a destination node having a said directional cost associated therewith, the method comprising:
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generating a set of restrictive costs associated with directional paths between said border nodes; and
selecting a path for routing of said call via a pair of said border nodes in dependence on said set of restrictive costs;
wherein said set of restrictive costs is generated by;
(a) assigning a unique identifier to each of said border nodes;
(b) selecting said unidirectional links in order of cost;
(c) for each of said unidirectional links selected, if a said identifier has previously been assigned to said source node for said link and said identifier has not previously been assigned to a said destination node for said link, assigning said identifier to said destination node and any further of said nodes, which are reachable from said destination node by traversing said unidirectional links selected thus far, to which said identifier has not previously been assigned;
(d) if said step (c) results in assignment to one of said border nodes of a said identifier not previously assigned to one of said border nodes, storing said directional cost of the last-selected unidirectional link as said restrictive cost for said directional path to said border node from one other of said border nodes to which said identifier was initially assigned in said step (a); and
(e) repeating said steps (b) to (d) at least until said restrictive cost has been stored for said directional paths between predetermined pairs of said border nodes.
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12. An apparatus for generating a set of restrictive costs associated with directional paths between selected nodes in a group of nodes of a network system wherein each of said nodes in said group is connected by a link to at least one other of said nodes in said group, and said link has a pair of directional costs associated therewith such that each of said links can be considered as a pair of oppositely-directed, unidirectional links each of which extends from a source node to a destination node and has a said directional cost associated therewith, said apparatus comprising memory for storing restrictive costs, and control logic configured to:
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(a) assign a unique identifier to each of said selected nodes;
(b) select said unidirectional links in order of cost;
(c) for each of said unidirectional links selected, if a said identifier has previously been assigned to a said source node for a said link and said identifier has not previously been assigned to a said destination node for a said link, to assign said identifier to said destination node and any other of said nodes, which are reachable from said destination node by traversing said unidirectional links selected thus far, to which said identifier has not previously been assigned;
(d) if said step (c) results in assignment to a said selected node of a said identifier not previously assigned to said selected node, to store in said memory said directional cost of the last-selected of said unidirectional link as said restrictive cost for said directional path to said selected node from said selected nodes to which said identifier was initially assigned in said step (a); and
(e) to repeat said steps (b) to (d) at least until said restrictive cost has been stored for said directional paths between said predetermined pairs of said selected nodes. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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21. A device for connection in a network system as one node in a group of nodes of said system such that each of said nodes in said group is connected by a link to at least one other of said nodes in said group, and a said link has a pair of directional costs associated therewith such that each of said links can be considered as a pair of oppositely-directed, unidirectional links each of which extends from a source node to a destination node and has a said directional cost associated therewith, said device comprising:
- control logic for generating a set of restrictive costs associated with directional paths between said selected nodes of said group; and
memory for storing said restrictive costs;
wherein said control logic is configured to generate said set of restrictive costs by;(a) assigning a unique identifier to each of said selected nodes;
(b) selecting said unidirectional links in order of cost;
(c) for each of said unidirectional links selected, if a said identifier has previously been assigned to a said source node for a said link and said identifier has not previously been assigned to a said destination node for said link, assigning said identifier to said destination node and any further of said nodes, which are reachable from said destination node by traversing said unidirectional links selected thus far, to which said identifier has not previously been assigned;
(d) if said step (c) results in assignment to a said selected node of a said identifier not previously assigned to said selected node, storing said directional cost of the last-selected of said unidirectional links as said restrictive cost for said directional path to said selected node from a said selected node to which said identifier was initially assigned in said step (a); and
(e) repeating said steps (b) to (d) at least until said restrictive cost has been stored for said directional paths between said predetermined pairs of said selected nodes. - View Dependent Claims (22)
- control logic for generating a set of restrictive costs associated with directional paths between said selected nodes of said group; and
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23. A computer program product, readable by a processor of a device for connection in a network system as one node in a group of nodes of said system such that each of said nodes in said group is connected by a link to at least one other of said nodes in said group, and a said link has a pair of directional costs associated therewith such that each of said links can be considered as a pair of oppositely-directed, unidirectional links each of which extends from a source node to a destination node and has a said directional cost associated therewith, said product comprising a computer program code means executable by said processor to generate a set of restrictive costs associated with directional paths between a selection of said nodes of said group by performing the steps of:
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(a) assigning a unique identifier to each of said selected nodes;
(b) selecting said unidirectional links in order of costs;
(c) for a said unidirectional link selected, if a said identifier has previously been assigned to a said source node for said link and said identifier has not previously been assigned to said destination node for said link, assigning said identifier to said destination node and any further of said nodes, which are reachable from said destination node by traversing said unidirectional links selected thus far, to which said identifier has not previously been assigned;
(d) if said step (c) results in assignment to a said selected node of a said identifier not previously assigned to said selected node, storing said directional cost of the last-selected of said unidirectional links as said restrictive cost for said directional path to a said-selected node from a said-selected node to which said identifier was initially assigned in said step (a); and
(e) repeating said steps (b) to (d) at least until said restrictive cost has been stored for said directional paths between said predetermined pairs of said selected nodes.
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Specification