Wavelength allocation in a ring

DETAILED DESCRIPTION It is an object of the present invention to provide a method of wavelength allocation that allows creating a fully meshed network at the optical layer when the nodes are connected, at the physical layer, in a ring.
In one aspect of the invention there is provided in a D/WDM ring with n add/drop nodes connected over a forward and a reverse fiber, a method of allocating a wavelength between each pair of nodes for obtaining a fully meshed network, comprising, determining an add/drop requirement N.
sub.
a for all nodes of the ring, a fiber requirement N.
sub.
f for each span of the ring and the minimum number N of wavelengths/span, preparing a hop table with all nodes nj and all wavelengths .
lambda.
.
sub.
i for the ring and selecting an origin for the hop table by defining a node of origin and a first wavelength, if N.
sub.
a.
ltoreq.
N.
sub.
f, determining an initial hop vector comprising a set of n initial forward hop values, generating all hops for all nodes and all wavelengths using the initial hop values and recording all the hop values in the hop table, and equipping each node with wavelength-specific receivers and transmitters according to a source-destination table prepared from the hop table.
The wavelengths requirement is N.
sub.
f.
Advantageously, the method of the invention uses a minimum number of wavelengths and a same wavelength set on each fiber, with the constraint that a wavelength is used at most once on any resource (add/drop node, fiber).
This method can be readily incorporated in an engineering tool, which significantly simplifies design of the network configuration.
The benefits of this method are thus a reduction of the cost of optical equipment, and a simplification of the network configuration.