What is claimed is:
1 . A transparent optical overlay network for providing end-to-end optical spectrum services over multiple transparent optical network domains, said transparent optical overlay network comprising:
network domain interface devices, NDIDs, provided between domain boundaries of adjacent transparent optical network domains and not forming a part of the adjacent transparent optical network domains, wherein each of the NDIDs is adapted to monitor and adjust incoming optical signals received by the NDID from a first transparent optical network domain and to monitor and adjust outgoing optical signals output by the NDID to an adjacent second transparent optical network domain; and an overlay network controller adapted to manage and control the end-to-end optical spectrum services by controlling the NDIDs and adapted to collect telemetry data for optical spectrum service characterization of the optical spectrum services.
2 . The transparent optical overlay network according to claim 1 , wherein the overlay network controller is adapted to process telemetry data, in particular Q-values, Bit Error ratios, signal power level data, collected from the NDIDs to perform continuously a long term performance monitoring of the end-to-end optical spectrum services and/or participating transparent optical network domain parameters and their conformance with underlying service level agreement, SLA, parameters.
3 . The transparent optical overlay network according to claim 1 , wherein each of the NDIDs comprises signal monitoring means having an input signal monitoring unit adapted to monitor incoming optical signals received by the NDID from the first transparent optical network domain in an incoming optical signal spectrum and having an output signal monitoring unit adapted to monitor outgoing optical signals transmitted by the NDID to the second transparent optical network domain in an outgoing optical spectrum to generate monitoring data supplied by the input signal monitoring unit and supplied by the output signal monitoring unit to a controller integrated in the NDID.
4 . The transparent optical overlay network according to claim 3 , wherein the signal monitoring means of the NDID are adapted to monitor a signal power, a signal power spectral density, an OSNR, a GSNR, chromatic dispersion or PMD of incoming optical signals and/or of outgoing optical signals.
5 . The transparent optical overlay network according to claim 4 , wherein the signal monitoring means of the NDID are adapted to monitor the performance of the incoming optical signal spectrum and/or in the outgoing optical signal spectrum of the adjacent optical network domains and/or wherein the signal monitoring means of the NDID are adapted to perform channel probing of optical channels in the incoming optical signal spectrum and/or in the outgoing optical signal spectrum of the adjacent optical network domains.
6 . The transparent optical overlay network according to claim 3 , wherein the signal monitoring means include the ability to provide telemetry data for the transparent optical overlay network controller for incoming and outcoming spectrum characterization, long-term monitoring and Service Level Agreement, SLA policing.
7 . The transparent optical overlay network according to claim 1 , wherein each of the NDIDs comprises signal adjustment means having at least one input signal adjustment unit adapted to adjust incoming optical signals received by the NDID from the first transparent optical network domain in an incoming optical signal spectrum in response to control signals received by the at least one input signal adjustment unit from a controller integrated in the NDID and/or from the overlay network controller and having at least one output signal adjustment unit adapted to adjust outgoing optical signals transmitted by the NDID to the second adjacent transparent optical network domain in an outgoing optical signal spectrum in response to control signals received by the at least one output signal adjustment unit from the controller integrated in the NDID and/or from the overlay network controller.
8 . The transparent optical overlay network according to claim 7 , wherein the input signal adjustment unit of the NDID is adapted to shutdown, attenuate, amplify, filter, switch, and/or to equalize the incoming optical signals received by the NDID from the first transparent optical network domain in the incoming optical signal spectrum in response to control signals received by the input signal adjustment unit from the controller integrated in the NDID and/or from the overlay network controller.
9 . The transparent optical overlay network according to claim 8 , wherein the input signal adjustment unit of the NDID comprises at least one N:M wavelength selective switch, WSS, where N≥1 and M≥2, adapted to switch or route the incoming optical signals received by the NDID from the first transparent optical network domain to the second transparent optical network domain in response to control signals received by the input signal adjustment unit from the controller integrated in the NDID and/or from the overlay network controller.
10 . The transparent optical overlay network according to claim 7 , wherein the output signal adjustment unit of the NDID is adapted to gradually enable, amplify, equalize and/or to pre-emphasize the outgoing optical signals transmitted by the NDID to the second transparent optical network domain in the outgoing optical signal spectrum in response to control signals received by the output signal adjustment unit from the controller integrated in the NDID and/or from the overlay network controller.
11 . The transparent optical overlay network according to claim 7 , wherein the input signal adjustment unit and output signal adjustment unit of the NDID is further adapted to perform ASE noise insertion and/or dummy channel insertion in response to control signals received by the output signal adjustment unit from the controller integrated in the NDID and/or from the overlay network controller.
12 . The transparent optical overlay network according to claim 7 , wherein the output signal adjustment unit comprises an EDFA array with optical signal amplifiers for signal amplification of optical signals in response to control signals received by the output signal adjustment unit from the controller integrated in the NDID and a variable optical attenuator, VOA, array.
13 . The transparent optical overlay network according to claim 1 , wherein the NDID comprises a control and data interface for connection to the overlay network controller of the transparent optical overlay network.
14 . The transparent optical overlay network according to claim 1 , wherein the transparent optical network domains comprise associated domain controllers connected to the overlay network controller of the transparent optical overlay network to exchange information about a network domain topology, resources and services in the transparent optical network domains available to the transparent optical overlay network.
15 . A network domain interface device, NDID, for a transparent optical overlay network used for providing end-to-end optical spectrum services over multiple transparent optical network domains, said transparent optical overlay network comprising:
the NDID being provided between domain boundaries of two adjacent transparent optical network domains and not forming a part of the adjacent transparent optical network domains, wherein the NDID is adapted to monitor and adjust incoming optical signals received by the NDID from a first transparent optical n