K-alternate channel selection for the routing, wavelength assignment and spectrum allocation in flexible optical WDM networks

1. A computer implemented method in a communications system including an optical flexible wavelength division multiplexing FWDM network, comprising:

i) finding an optimal set of line rates for a requested data rate of each connection in said FWDM using a channel selection for a total spectrum requirement for said set of line rates that is minimal;

ii) determining available channels with sufficient spectrum for each said connection in a given set of said each connection in a specific order;

iii) ascertaining K-distinct shortest routes for each said connection;

iv) acquiring spectrum availability information for each said K-distinct routes using said spectrum availability information of all links along a respective route of said K-distinct routes; and

v) selecting, among said K-distinct routes, a route having an available channel at a lowest wavelength so that all said connections are confined to lowest available wavelengths, thereby minimizing amount of spectrum needed for communication in said FWDM network,

steps i)-v) being carried out by a computer.

2. A computer implemented method implemented in an optical flexible wavelength division multiplexing FWDM network, comprising:

i) finding a first channel out of available channels with sufficient spectrum on a given route out of available channels in an optical FWDM network;

ii) finding a second channel at a lower wavelength out of said available channels for minimizing total spectrum on said given route; and

iii) selecting a channel out of said available channels on K-distinct shortest routes; and finding line rates of channels using a predetermined channel selection;

steps i)-iii) being implemented by a computer.