A method for network provisioning, comprising: responsive to receiving a request for a virtual optical network, hereinafter abbreviated to VON, calculating a first mapping pattern , the first mapping pattern including a mapping of at least two virtual nodes (V1, V2, V3) to at least two physical nodes (A, B, C, D, E) in an optical network ; evaluating the first mapping pattern for compliance with the request, wherein distance-adaptive routing and spectral slot assignment is performed on the first mapping pattern ; when the first mapping pattern complies with the request , designating the first mapping pattern as a first valid mapping pattern; calculating at least a second mapping pattern , the at least second mapping pattern including a mapping of at least two virtual nodes (V1, V2, V3) to at least two physical nodes (A, B, C, D, E) in an optical network, wherein the at least second mapping includes a virtual node (V3) that is also included in the first mapping pattern and wherein that virtual node (V3) is mapped to a different physical node in the first mapping pattern than it is mapped to in the at least second mapping pattern ; evaluating the at least second mapping pattern for compliance with the request, wherein distance-adaptive routing and spectral slot assignment is performed on the at least second mapping pattern ; when the at least second mapping pattern complies with the request, designating the at least second mapping pattern as a second valid mapping pattern; and selecting , from valid mapping patterns for the request including at least the first valid mapping pattern and the second valid mapping pattern, a final mapping pattern, wherein the final mapping pattern has at least one of a lowest spectral slot layer and a smallest spectral slot usage among the valid mapping patterns. responsive to receiving a request for a virtual optical network, hereinafter abbreviated to VON, calculating a first mapping pattern , the first mapping pattern including a mapping of at least two virtual nodes (V1, V2, V3) to at least two physical nodes (A, B, C, D, E) in an optical network ; evaluating the first mapping pattern for compliance with the request, wherein distance-adaptive routing and spectral slot assignment is performed on the first mapping pattern ; when the first mapping pattern complies with the request , designating the first mapping pattern as a first valid mapping pattern; calculating at least a second mapping pattern , the at least second mapping pattern including a mapping of at least two virtual nodes (V1, V2, V3) to at least two physical nodes (A, B, C, D, E) in an optical network, wherein the at least second mapping includes a virtual node (V3) that is also included in the first mapping pattern and wherein that virtual node (V3) is mapped to a different physical node in the first mapping pattern than it is mapped to in the at least second mapping pattern ; evaluating the at least second mapping pattern for compliance with the request, wherein distance-adaptive routing and spectral slot assignment is performed on the at least second mapping pattern ; when the at least second mapping pattern complies with the request, designating the at least second mapping pattern as a second valid mapping pattern; and selecting , from valid mapping patterns for the request including at least the first valid mapping pattern and the second valid mapping pattern, a final mapping pattern, wherein the final mapping pattern has at least one of a lowest spectral slot layer and a smallest spectral slot usage among the valid mapping patterns. <EOS>