Method for optimizing a mostly optical network
First Claim
1. A method for optimizing the routing of a data stream using Asynchronous Transfer Mode (ATM) over an optical network employing Wavelength Division Multiplexing (WDM), wherein said network comprises a plurality of nodes interconnected by physical links comprised of optical transmission media suitable for carrying data at a plurality of carrier wavelengths, said method comprising the steps of:
- determining the number of hops for a plurality of logical links between pairs of said nodes, wherein each logical link is associated with a distinct Virtual Path Channel (VPC);
assigning a first carrier wavelength to each logical link having only one hop; and
for each logical link having more than one hop, i) employing a non-deterministic algorithm with the objective function of minimizing the total number of hops to separate each logical link into a sequence of logical link portions, or Virtual Path Links (VPLs);
ii) selectively grouping at least a first VPL associated with a first VPC with a second VPL associated with a second VPC to form Virtual Paths (VPs) between adjacent ones of said nodes; and
iv) assigning a second carrier wavelength to each said VP.
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Abstract
Method for forming the virtual topology (21-45) of an ATM-layer where the ATM-layer is carried over an optical network (1) where inputs such as the physical topology (2-8, 11-16) and constraints of physical nature are given, thereafter forming node-pairs with end-to-end connections according to some known optimal routing algorithm, and finally applying a non-deterministic mathematical approach to obtain an optimal virtual topology with the objective of minimising the need for necessary electrical processing (50, 60, 70, 80) in the nodes (11-16) of the network (1).
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Citations
4 Claims
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1. A method for optimizing the routing of a data stream using Asynchronous Transfer Mode (ATM) over an optical network employing Wavelength Division Multiplexing (WDM), wherein said network comprises a plurality of nodes interconnected by physical links comprised of optical transmission media suitable for carrying data at a plurality of carrier wavelengths, said method comprising the steps of:
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determining the number of hops for a plurality of logical links between pairs of said nodes, wherein each logical link is associated with a distinct Virtual Path Channel (VPC);
assigning a first carrier wavelength to each logical link having only one hop; and
for each logical link having more than one hop, i) employing a non-deterministic algorithm with the objective function of minimizing the total number of hops to separate each logical link into a sequence of logical link portions, or Virtual Path Links (VPLs);
ii) selectively grouping at least a first VPL associated with a first VPC with a second VPL associated with a second VPC to form Virtual Paths (VPs) between adjacent ones of said nodes; and
iv) assigning a second carrier wavelength to each said VP.- View Dependent Claims (2, 3, 4)
changing the wavelength of an arbitrary VPL;
checking whether the VPs in adjacent links can be concatenated to a VPL;
concatenate said VPs in adjacent links into a VPL if said VPs are of the same wavelength and if all VPs of said wavelength belong to traffic streams which cross all VPs of said VPL.
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3. The method recited in claim 2, further comprising the step of adding a penalty term to the objective function in that state if at least one constraint is violated, and then accepting said state with decreasing probability.
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4. The method recited in claim 2, characterized in that the steps are repeated a predefined number of times or until no more improvement according to the objective function is reached, choosing the obtained state-space as the virtual topology for the network.
Specification