In order to prevent a signal which a terminal station does not require from being intercepted by the terminal station without greatly changing the power of optical signals to be transmitted from a node to the terminal station, a node device is provided with: a first optical unit which outputs a first optical signal received from a first terminal station and addressed to a second terminal station, and a second optical signal received from the first terminal station, addressed to a third terminal station, and having a different wavelength band from the first optical signal; and a second optical unit to which the first and second optical signals outputted from the first optical unit are inputted, and which shifts the frequency of the first optical signal by a predetermined amount to create a fourth optical signal, passes the second optical signal without any change, couples the second and fourth optical signals, and transmits a resultant signal to the third terminal station.

Example embodiments of the present invention relate to optical wavelength directing devices used to construct compact optical nodes.

Systems, apparatus, and methods for packetized clocks may include a packet interface to carry the rate of a client to a sigma-delta modulator that generates a clock at the required rate inside the chip itself there by removing the need for off-chip analog PLLs. The packetized clock may include a packet interface that receives a flow credit packet that includes a plurality of flow credit counts, one flow credit count for each data flow, and forwards a flow credit count for each data flow to one of a plurality of clock generators to generate a new clock signal for each data flow.

Novel tools and techniques are provided for implementing network timing functionality. In some embodiments, a grand master clock(s) might receive a first timing signal from a global positioning system (“GPS”) source via a GPS antenna(s), and might send a second timing signal (which might be based at least in part on the first timing signal) to a slave clock(s), in some cases, via one or more network elements or the like. A computing system might calculate various transmission times for the second timing signal to be transmitted between the grand master clock(s) and the slave clock(s), and might calculate any time delay differences in the transmission times, might generate a third timing signal based at least in part on the calculated time delay differences (if any), and might send the third timing signal to one or more network elements, thereby providing Accurate Synchronization as a Service (“ASaaS”) functionality.

According to an example, nodes request access to a shared resource in a prioritized optical arbitration system. Each node attempts to extract a wavelength corresponding to a priority level selected by the node from a waveguide. A node is granted access to the resource according to priority level, and is to extract from the waveguide the corresponding wavelength.

Systems and methods for adaptive and automated traffic engineering of data transport services may include learning the demand between devices and data paths based on application workloads, prediction of traffic demand and paths based on the workload history, provisioning and management of data paths (i.e. network links) based on the predicted demand, and real-time monitoring and data flow adaptation. Systems and methods for adaptive and automated traffic engineering of data transport services may also include learning the variation of traffic (data flow in the network) on various links (data paths) of the network topology using historical data (e.g. a minute, an hour, a day, or a week of data), predicting the data flow pattern for a time interval, and provisioning the services to steer data to meet the application requirements and other network wide goals (e.g., load balancing).

The present invention relates to adding and dropping signals in a node of an optical network, wherein the node includes a reconfigurable optical add/drop multiplexer (ROADM). The reconfigurable optical add/drop multiplexer (ROADM) comprises output ports and at least one add port connectable to at least one line interface of the network and adapted to receive a modulated optical signal from the line interface. Selection units are connected to one of said add ports and adapted to forward the respective signals to a selected output terminal. A plurality of broadcast units is adapted to broadcast signals forwarded by the selection. Then a multiplexing and selecting device or apparatus selects and multiplexes the optical signals broadcast via broadcast unit output terminals into a plurality of wavelength-division multiplexing (WDM) optical signals and forwards the same to output ports of the reconfigurable optical add-drop multiplexer (ROADM).

A method (10) of controlling optical signal power levelling in an optical communication network node configured to apply an optical attenuation, α, to a pass-through optical signal. The method comprises: a. performing the following steps i. to iii. until an attenuation variation value, Δα, is greater than a preselected attenuation variation threshold value (18), Δα.sub.TH: i. measuring (12) an optical signal power of an optical signal; ii. calculating (14) a difference, ΔP, between the measured optical signal power and a target optical signal power; iii. calculating (16) a value for the attenuation variation, Δα, to be applied to the optical attenuation taking account of ΔP; b. obtaining (20) a current value of the optical attenuation, α.sub.n, and obtaining (22) a new optical attenuation value, α.sub.n+1, in dependence on the current value of the optical attenuation, a current value of the attenuation variation, Δα.sub.n, and at least an earlier value of the attenuation variation, Δ.sub.αn−1; and c. generating (24) a control signal arranged to configure the node to apply the new optical attenuation value, α.sub.n+1.

An optical circuit switching matrix includes a plurality of optical ports, each optical port being optically coupled to a respective one of a plurality of user nodes and an optical coupler having at least one input port optically coupled to the plurality of optical ports, and an output port. The optical circuit switching matrix also includes a wavelength demultiplexer having an input optically coupled to the output port of the optical coupler, and a plurality of output ports, each output port being optically coupled to a respective one of the plurality of optical ports.

Systems and methods for performing wavelength conflict detection are provided. These are to detect situations in optical networks where two instances of the same wavelength channel have been added. Wavelength conflict detection is performed for each of a plurality of possible wavelength channels that could be present in an optical signal, each wavelength channel that is present modulated by a pilot tone signal with a respective pilot tone frequency, the pilot tone signal carrying M-ary pilot tone data, M=2.sup.n, n≧1, with a respective one of M different sequences being used to represent each of M possible data values over a data value period. Conflict detection for each wavelength channel involves performing correlation peak detection using each of the M different sequences to determine correlation peaks for each of the M different sequences, and, based on the determined correlation peaks, determining whether multiple instances of the wavelength channel are present in the optical signal.