Method of allocating bandwidth in an optical network

Proposed is a method for allocating bandwidth in an optical network. A bandwidth grid containing first bandwidth slots of a lower bandwidth and higher bandwidth slots of a higher bandwidth is provided. A set of requests for respective data transmission connections with respective data rates and respective shortest path metrics is provided. Shorter distances, over which a data signal may be transmitted transparently at the respective data rate within the lower bandwidth, and longer distances, over which a data signal may be transmitted transparently at the respective data rate within the higher bandwidth, are provided. Bandwidth slots of the lower bandwidth for those of the data transmission connections, whose respective shortest path metric is smaller than their respective shorter distance, are allocated. Finally, bandwidth slots of the lower or the higher bandwidth are allocated for the further data transmission connections, using respective numbers of necessary OEO regenerations.