Routing method for a hierarchical communications network, and a hierarchical communications network having improved routing
First Claim
1. A method of providing routing information and for selecting routes in a communications network comprising a number of mutually isolated areas (A1, A2, A3, A4) at a first level, said first level areas (A1 A2 A3 A4) being linked at a second level;
- and routing devices (R1-1, R1-2 . . . , R2-5) provided at both said first and second levels for selecting routes on the basis of a cost function and routing information stored in said first level routing devices (R1-1, R1-2, . . . ); and
wherein at least some first level areas (A1, A3, A4) are directly linked to more than one second level routing device (A1;
R2-1 and R2-5;
A3;
R2-1, R2-2, R2-4 and R2-5;
A4;
R2-3, R2-4 and R2-5);
the method comprising the steps of;
providing to the first level routing devices (e.g., R1-1, R1-2, R1-3) of a given first level area (e.g., A1), routing information relating to said given first level area (A1) and to direct links from said given first level area (A1) to second level routing devices (R2-1, R2-5);
providing additional routing information to first level routing devices (R1-1, R1-2, . . . ) of first level areas (A1, A3, A4) which are directly linked to more than one second level routing device (A1;
R2-1 and R2-5;
A3;
R2-1, R2-2, R2-4 and R2-5;
A4;
R2-3, R2-4 and R2-5), said additional routing information relating only to routing information of second level routing devices and being provided by second level routing devices (R2-1, R2-5) which are directly linked to said given first level area (A1);
determining costs of alternative communication routes from said first-mentioned routing information and said additional routing information; and
selecting a communication route from said alternative communication routes.
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Accused Products
Abstract
A method and apparatus for selecting routes in a hierarchical communications network wherein a number of mutually isolated areas are provided at a first level, which areas are mutually linked at a second level. In the network, routing devices are provided at both levels. For selecting a route from a first area to a second area, use is made of routing information stored in the routing devices of the first level, relating to the first level and to reaching the nearest routing device of the second level. Use is also made, in the routing devices of the first level, of routing information relating to the second level.
134 Citations
21 Claims
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1. A method of providing routing information and for selecting routes in a communications network comprising a number of mutually isolated areas (A1, A2, A3, A4) at a first level, said first level areas (A1 A2 A3 A4) being linked at a second level;
- and routing devices (R1-1, R1-2 . . . , R2-5) provided at both said first and second levels for selecting routes on the basis of a cost function and routing information stored in said first level routing devices (R1-1, R1-2, . . . ); and
wherein at least some first level areas (A1, A3, A4) are directly linked to more than one second level routing device (A1;
R2-1 and R2-5;
A3;
R2-1, R2-2, R2-4 and R2-5;
A4;
R2-3, R2-4 and R2-5);the method comprising the steps of; providing to the first level routing devices (e.g., R1-1, R1-2, R1-3) of a given first level area (e.g., A1), routing information relating to said given first level area (A1) and to direct links from said given first level area (A1) to second level routing devices (R2-1, R2-5); providing additional routing information to first level routing devices (R1-1, R1-2, . . . ) of first level areas (A1, A3, A4) which are directly linked to more than one second level routing device (A1;
R2-1 and R2-5;
A3;
R2-1, R2-2, R2-4 and R2-5;
A4;
R2-3, R2-4 and R2-5), said additional routing information relating only to routing information of second level routing devices and being provided by second level routing devices (R2-1, R2-5) which are directly linked to said given first level area (A1);determining costs of alternative communication routes from said first-mentioned routing information and said additional routing information; and selecting a communication route from said alternative communication routes. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
- and routing devices (R1-1, R1-2 . . . , R2-5) provided at both said first and second levels for selecting routes on the basis of a cost function and routing information stored in said first level routing devices (R1-1, R1-2, . . . ); and
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13. In a communications network comprising a number of mutually isolated areas (A1, A2, A3, A4) at a first level, said first level areas (A1, A2, A3, A4) being linked at a second level;
- and routing devices (R1-1, R1-2 . . . , R2-5) provided at both said first and second levels for selecting routes on the basis of a cost function and routing information stored in said first level routing devices (R1-1, R1-2, . . . ); and
wherein at least some first level areas (A1, A3, A4) are directly linked to more than one second level routing device (A1;
R2-1 and R2-5;
A3;
R2-1, R2-2, R2-4 and R2-5;
A4;
R2-3, R2-4 and R2-5);the improvement comprising the combination of; means for providing to the first level routing devices (e.g., R1-1, R1-2, R1-3) of a given first level area (e.g., A1), routing information relating to said given first level area (A1) and to direct links from said given first level area (A1) to second level routing devices (R2-1, R2-5); means for providing additional routing information to first level routing devices (R1-1, R1-2, . . . ) of first level areas (A1, A3, A4) which are directly linked to more than one second level routing device (A1;
R2-1 and R2-5;
A3;
R2-1, R2-2, R2-4 and R2-5;
A4;
R2-3, R2-4 and R2-5), said additional routing information relating only to routing information of second level routing devices and being provided by second level routing devices (R2-1, R2-5) which are directly linked to said given first level area (A1);means for determining costs of alternative communication routes from said first-mentioned routing information and said additional routing information; and means for selecting a communication route from said alternative communication routes. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21)
- and routing devices (R1-1, R1-2 . . . , R2-5) provided at both said first and second levels for selecting routes on the basis of a cost function and routing information stored in said first level routing devices (R1-1, R1-2, . . . ); and
Specification