Optical transmission network (20, 30) for transmitting optical signals in wavelength-division multiplex mode, comprising a plurality of optical network elements (401-405, 510, 520, 530) arranged as a ring network, the plurality of optical network elements comprising a plurality of first optical network elements and two second optical network elements, wherein a hierarchically higher-level network node is connected to each of the two second optical network elements, wherein the transmission network is designed in such a way that, in the event of failure of one of the two hierarchically superordinate network nodes, re-routing takes place on the IP layer, and wherein the optical transmission network is designed for the use of multi-layer restoration from optical failure, MLR-O, wherein - adjacent optical network elements are respectively connected to each other via a bidirectional optical transmission line (311, 321; 312, 322), - a first optical signal path and a second optical signal path, the second optical signal path running in opposite direction to the first one, are formed along the ring network by the bidirectional transmission lines, - each of the plurality of first optical network elements is adapted to simultaneously couple an optical wavelength division multiplex signal into both optical signal paths by means of passive optical couplers (630, 640), and to couple out a respective optical wavelength division multiplex signal from each of the two signal paths by means of passive optical dividers (610, 620) and to automatically select one of the coupled-out optical wavelength division multiplex signals for further processing, - each of the two second optical network elements (510, 520, 530) is designed as a reconfigurable optical add/drop multiplexer which is further adapted to couple out one optical wavelength division multiplexed signal from each of the two signal paths and to automatically select one of the coupled-out optical signals for further processing, and - the two second optical network elements (510, 520, 530) are configured such that the first and second signal paths are interrupted for each transmission wavelength used in at least one of the two second optical network elements (510, 520, 530). - adjacent optical network elements are respectively connected to each other via a bidirectional optical transmission line (311, 321; 312, 322), - a first optical signal path and a second optical signal path, the second optical signal path running in opposite direction to the first one, are formed along the ring network by the bidirectional transmission lines, - each of the plurality of first optical network elements is adapted to simultaneously couple an optical wavelength division multiplex signal into both optical signal paths by means of passive optical couplers (630, 640), and to couple out a respective optical wavelength division multiplex signal from each of the two signal paths by means of passive optical dividers (610, 620) and to automatically select one of the coupled-out optical wavelength division multiplex signals for further processing, - each of the two second optical network elements (510, 520, 530) is designed as a reconfigurable optical add/drop multiplexer which is further adapted to couple out one optical wavelength division multiplexed signal from each of the two signal paths and to automatically select one of the coupled-out optical signals for further processing, and - the two second optical network elements (510, 520, 530) are configured such that the first and second signal paths are interrupted for each transmission wavelength used in at least one of the two second optical network elements (510, 520, 530).