Abstract: A method of monitoring a differential group delay, DGD, of an optical communications signal having a polarisation multiplexed modulation format is described. The method includes the steps of receiving a signal and performing analogue to digital conversion of the signal to generate a digitised signal corresponding to one polarisation of the signal and to generate another digitised signal corresponding to another polarisation of the signal, and applying a polarisation mode dispersion, PMD, compensation to each of the digitised signals. The method further includes the steps of obtaining an indication of the channel transfer function of the optical communications signal, determining a DGD in dependence on the indication of the channel transfer function, determining a delay between the PMD compensated digitised signals, subtracting the delay from the DGD to obtain a corrected DGD, and generating and transmitting a monitoring signal with an indication of the corrected DGD.

Abstract: A method for acquiring an optical fiber connection relation includes: acquiring, by a first unit, first port identification information of a optical fiber, where the first port identification information of the optical fiber is pre-stored in a first storage unit; correlating port identification information of the first unit that is connected to the first storage unit with the first port identification information; acquiring, by a second unit, second port identification information of the optical fiber, where the second port identification information of the optical fiber is pre-stored in a second storage unit; correlating port identification information of the second unit that is connected to the second storage unit with the second port identification information; acquiring, by a management control unit, correlation information; and determining an optical fiber connection relation between the first unit and the second unit.

Abstract: The control device includes a power-saving control unit that intermittently repeats, based on a power saving permission signal transmitted from the master station apparatus, power saving control in which the slave station stops or reduces power supply to a transmitter or a receiver for a predetermined pause duration while maintaining a communication link and a monitoring unit that monitors out of synchronization by comparing a synchronization signal received from the OLT and a time of the ONU. The control device shifts from a registered state to a deregistered state when the monitoring unit detects the out of synchronization. On the other hand, after the pause duration of the power saving control, the control device suppresses the shift to the deregistered state due to the detection of the out of synchronization.

Abstract: Techniques are provided for estimation of the chromatic dispersion (CD) in an optical signal received by an optical receiver. The techniques involve iteratively adjusting dispersion compensation coefficients of one or more filters configured to compensate for the CD in the received optical signal. At each iteration of the dispersion compensation coefficient adjustment, electrical domain signals are filtered to generate digitally-filtered signals. The electrical domain signals are generated based on the received optical signal. Also at each iteration of the dispersion compensation coefficient adjustment, an amplitude histogram of the digitally-filtered signals is generated. The amplitude histograms generated at each iteration are evaluated to generate an estimate of the chromatic dispersion in the received optical signal.

Abstract: Methods and apparatuses are provided to determine whether SBS is present in a fiber of a communication system. An SBS detector comprising a circulator and a detector is used to determine whether SBS is occurring in a fiber. An input optical signal can be received at a first port of the circulator and output at a second port of the circulator where the fiber is connected. The circulator can receive a reflected optical signal from the fiber at the second port of the circulator and output the reflected optical signal at the third port. A detector connected to third port of the circulator receives the reflected optical signal and converts the reflected optical signal to a D.C. voltage.

Abstract: According to an embodiment, a semiconductor device includes an analog/digital conversion unit, a pulse width modulation unit outputting a transmission signal, the transmission signal being a pulse pattern corresponding to a digital signal output from the analog/digital conversion unit, a reference signal generation unit generating a reference signal, the reference signal being a fixed pulse pattern. The device includes a first control unit selecting one of the transmission signal and the reference signal, a light emitting element drive unit outputting a drive current based on the transmission signal or the reference signal, a light emitting element driven by the light emitting element drive unit. The device includes an optical receiving unit converting the optical signal into a voltage signal, and a demodulation unit demodulating the voltage signal into a digital signal based on the transmission signal or the reference signal.

Abstract: A comparator (11) outputs, out of an electrical signal input from a trans impedance amplifier (TIA) via a coupling capacitor, pulses having amplitudes equal to or larger than a reference value as a comparison output signal (Cout). An analog holding circuit (12) charges a holding capacitor with each pulse contained in the comparison output signal (Cout) and also removes a DC voltage obtained by the charging via a discharging resistor, thereby generating a holding output signal (Hout) that changes in accordance with the presence/absence of input of an optical signal. This allows to perform an autonomous operation without any necessity of an external control signal and properly detect the presence/absence of input of an optical signal.

Abstract: The invention relates to products, methods and devices for remote communication or control using chromogenic materials. Several samples including at least one kind of chromogenic materials are simultaneously irradiated or radiated together by an appropriate entangled radiation, e.g, gamma, X, ultraviolet or visible radiation, provided by a cascade from an atomic source, or by the target of a linear particle accelerator or by a non-linear crystal. When the samples are separated, one of them, qualified as the master, is stimulated by a traditional method that uses infrared or white radiation or by heating, and a signal is measured that represents the partially correlated excess variation of opacity or coloration of the other sample(s), qualified as slave(s). There is no known method of interference between the master and the slaves. The slave(s) are the only ones capable of instantaneously receiving the signal from the master through all media and from any distance.

Abstract: A personnel monitoring system. The personnel monitoring system includes a host node having an optical source for generating optical signals, and an optical receiver. The personnel monitoring system also includes a plurality of fiber optic sensors for converting at least one of vibrational and acoustical energy to optical intensity information, each of the fiber optic sensors having: (1) at least one length of optical fiber configured to sense at least one of vibrational and acoustical energy; (2) a reflector at an end of the at least one length of optical fiber; and (3) a field node for receiving optical signals from the host node, the field node transmitting optical signals along the at least one length of optical fiber, receiving optical signals back from the at least one length of optical fiber, and transmitting optical signals to the optical receiver of the host node.

Abstract: In the present invention, unlike a conventional circuit, discrimination is not made by integrating a logical code that includes “0” and “1” to some extent and produced from a random code, but repetition of an identical pattern of a well-known preamble signal added to a head portion of a signal is discriminated when a bit-rate of the signal is changed. More specifically, the repetition of the identical pattern is converted into a consecutive identical signal to generate the consecutive identical signal (having a length of tens bits to thousands bits). Although the consecutive identical signal is longer than a same-code continuation length included in the signal, and is shorter than a time constant necessary to the conventional circuit by about one to three digits. Therefore, an integration time can be shortened to the same degree as the generated consecutive identical signal length, and the bit-rate can be discriminated at high speed within a preamble signal receiving time.

Abstract: An apparatus for computing optical network characteristics may comprise: a plurality of network elements arranged into two or more domains; two or more optical computation engines, each of the two or more optical computation engine associated with a respective one of the two or more domains; and a centralized path computation engine configured to interface with the two or more optical computation engines to calculate one or more characteristics of the optical path. Each of the two or more domains may comprise one or more network elements sharing a common operational characteristic. The plurality of network elements may be in optical communication along an optical path, the optical path including a first network element at an origin of the optical path and a final network element at a terminus of the optical path.

Abstract: The present invention relates to an optical receiver (1) for receiving alternating-light data signals and for storing electrical energy obtained from extraneous light, having a photodiode (2) for receiving light, which comprises extraneous light and an alternating-light data signal component with a higher frequency in comparison to the extraneous light, and for converting the light into a photocurrent (IP) which comprises a data signal current (IN) and an extraneous light current (IF) said receiver additionally comprises a coupling unit (3) for coupling in and separating the data signal current generated by the optical alternating-light data signal component from the extraneous light current generated by the extraneous light, an amplifying unit (4) for amplifying the data signal current and an energy storage unit (5) which is charged by the extraneous light current (IF) and which includes a circuit for increasing voltage, wherein the energy charged in the energy storage unit (5) is used for at least partially

Abstract: When a circuit that calculates a frequency offset using a shape of a frequency spectrum is implemented by hardware, the circuit size can be reduced.

Abstract: In the optical receiver available for the RZ-DPSK modulation system, the difference in the received intensity due to the difference in the intensity or optical path of the optical signal cannot be corrected automatically, therefore, an optical receiver according to an exemplary aspect of the invention includes a first photodiode receiving a normal phase optical signal from a first output of a 1-bit delayed interferometer and outputting a positive signal; a second photodiode receiving a reversed phase optical signal from a second output of the 1-bit delayed interferometer and outputting a complementary signal; a differential transimpedance amplifier inputting the positive signal and the complementary signal and including a closed feedback loop for each input of the positive signal and the complementary signal; a level adjustment unit adjusting a signal level in the closed feedback loop; a photoelectric current detection unit detecting a photoelectric current generated in each of the first photodiode and the se

Abstract: The disclosure claims a method and system for detecting optical fibre connection.

Abstract: Changes in a signal are detected. The signal is repeatedly sampled in a synchronous manner during a predetermined interval to generate a captured eye diagram. At least one of a positive differential eye diagram or a negative differential eye diagram is generated from the captured eye diagram and a baseline eye diagram. The at least one positive or negative differential eye diagram is analyzed to determine whether a change in signal conditions is present.

Abstract: A method comprises: acquiring, for a number nSOP of varied State-Of-Polarization analysis conditions of the input optical signal, nSOP polarization-analyzed optical spectrum traces; mathematically discriminating said signal contribution from said noise contribution within said optical signal bandwidth using said polarization-analyzed optical spectrum traces, said mathematically discriminating comprising: obtaining a differential polarization response that is related to the optical spectrum of said signal contribution by a constant of proportionality; estimating the constant of proportionality of a differential polarization response to the optical spectrum of said signal contribution; estimating the optical spectrum of said noise contribution from said input optical signal, within said optical signal bandwidth using said constant of proportionality and said differential polarization response; and determining said in-band noise parameter on said input optical signal from the mathematically discriminated noise c

Abstract: The present disclosure relates to systems and methods for providing bandwidth-on-demand telecommunications services over next-generation optical transport networks (NG-OTN). One embodiment of a system providing bandwidth-on-demand services includes a next-generation optical transport network (NG-OTN) having an intelligent control plane (ICP) and new-generation synchronous optical network (NG-SONET) capabilities. A next-generation operation support subsystem (NG-OSS) is communicatively coupled to the NG-OTN. The NG-OTN and the NG-OSS are configured to provide the bandwidth-on-demand services.

Abstract: An optical transmitting/receiving system using a timing extracting method that allows a feed forward type of optimized structure exhibits increased cost and increased power consumption, therefore, an optical transmitting/receiving system according to the present invention includes an optical transmitter apparatus including a light source, an optical modulator, and a pseudo RZ carver; and an optical receiver apparatus including a coherent receiver, an AD converter, a main signal processing unit, and a timing extracting unit; wherein the pseudo RZ carver forms a dip in an optical signal phase-modulated with a frequency f by the optical modulator by dropping the optical intensity at a symbol transition point to approximate zero per n-symbol interval; the AD converter outputs a sample obtained by AD converting an electrical signal which is detected and outputted by the coherent receiver; the timing extracting unit extracts a clock component of a frequency f/n from the sample and derives from the clock component a

Abstract: A network comprising at least one host device having an interface card connected to a backplane of said host device, wherein said interface card comprises at least one cage for receiving a pluggable module which provides at least one embedded communication channel which exchanges performance monitoring data and configuration data between said pluggable module and a far end device.

Abstract: There is provided a method for determining the in-band noise in agile multichannel Dense Wavelength Division Multiplexing (DWDM) optical systems, where the interchannel noise is not representative of the in-band noise in the optical channel. The method relies on the analysis of two observations of the same input optical signal. In the two observations, the linear relationship between the optical signal contribution and the optical noise contribution (i.e. the observed OSNR) is different, which allows the discrimination of the signal and noise contributions in the input optical signal. In a first approach, the two observations are provided by polarization analysis of the input optical signal. In a second, the input optical signal is obtained using two different integration widths.

Abstract: A method for generating a visible signal for a data transmission frame in a visible-light communication system includes: receiving specific data constituted by a plurality of frames from a sender; checking and converting a received signal strength indication (RSSI) signal measured from the sender; whenever each frame of the specific data is consecutively received, checking the converted RSSI, determining a level of a visible signal for distinctively displaying a state of a corresponding communication channel, and transmitting the level of the visible signal to the sender; and when reception of the specific data has finished, transmitting a corresponding response message to the sender, according to whether the specific data has been successfully received.

Abstract: A method for an optical transmitter, receiver or transceiver allowing determination of a signal property of a first binary signal such as the modulation amplitude. The method applies a reference stage which is modulated by the signal content of the first binary signal to allow the determination.

Abstract: The invention describes method and an arrangement for transmitting an orthogonal frequency diversity multiplex signal via an optical filter. OFDM channels located near an edge of an OFDM spectrum are copied and shifted to an opposite edge of the OFDM spectrum and transmitted via the optical filter. At the receiver symbols are derived from original and the copied OFDM channels. Then the symbols having a better signal quality are elected for further processing.

Abstract: Changes in a signal are detected. The signal is repeatedly sampled in a synchronous manner during a predetermined interval to generate a captured eye diagram. At least one of a positive differential eye diagram or a negative differential eye diagram is generated from the captured eye diagram and a baseline eye diagram. The at least one positive or negative differential eye diagram is analyzed to determine whether a change in signal conditions is present.

Abstract: A control device includes: a first computing circuit which manipulates a parameter that changes a first characteristic in a processing device on the basis of a result of detecting the first characteristic of the processing device; an updating control circuit which stops the first computing circuit from manipulating the parameter when updating a function of the first computing circuit; an acquisition circuit which acquires relationship information indicating a relationship between an amount to be manipulated for the parameter and the amount of change in a second characteristic of the processing device that changes the first characteristic; and a second computing circuit which manipulates the parameter by an amount to be manipulated based on the relationship information acquired by the acquisition circuit and the amount of change in a result of detecting the second characteristic, while the first computing circuit is stopped from manipulating the parameter by the updating control circuit.

Abstract: Methods and arrangements for time distribution in an optical network system in the upstream direction. The information of a selected time reference frame and a calculated time stamp value of the frame based on a real-time clock of the optical line terminal (OLT) is sent from the OLT to the optical network unit (ONU) via the optical distribution network (ODN). When the time reference frame is sent to the ONU from the OLT via the ODN, the ONU records the arrival time of the frame based on a time reference made by the real-time clock of the ONU. The time difference between the arrival time and the time stamp value is calculated whereupon the OLT is informed of the calculated time difference. The OLT adjusts the real-time clock of the OLT in accordance with the time difference.

Abstract: An optical transmission system includes an optical transmitting apparatus that includes a polarization controller configured to change a polarization state of a signal light at an operating frequency included in a frequency range at which polarization trackability is obtained on a receiving side, based on a notified monitoring result, the optical transmitting apparatus being configured to output the signal light having the changed polarization state, and an optical receiving apparatus that is provided on the receiving side and includes a monitoring control unit configured to receive the signal light having the changed polarization state and monitor transmission quality of the received signal light, the optical receiving apparatus being configured to notify the optical transmitting apparatus of the monitoring result.

Abstract: An optical transport network signal (OTM) comprising at least one optical channel is received at a first network equipment. The optical transport network signal (OTM) is processed to extract optical data units (ODUk) for each optical channel (OCh). There is detection for defects during the processing. The optical data units are retransmitted within optical transport units (OTUk) towards a second network equipment. When a defect has been detected, the retransmitting comprises inserting an optical channel transport unit alarm indication signal (OTUk-AIS) in an optical channel transport unit (OTUk) containing optical channel data units (ODUk) that are affected by the detected defect.

Abstract: A technique includes using an emitter of an optical detector to emit a first optical signal and a receiver to acquire measurement of a second optical signal generated due to interaction of the first optical signal with a target. The technique includes scaling the acquired measurement based on a measure of optical crosstalk communication between the emitter and the receiver.

Abstract: A system may receive a group of electrical signals from an optical receiver and via a group of channels; identify a first signal, as a reference signal, that is received via a first channel; and identify a second signal, as an orthogonal signal, that is received via a second channel, where the second signal may be orthogonal to the first signal. The system may further measure a group of skew values based on a difference in arrival times between one or more other signals, of the group of electrical signals, and the reference signal or the orthogonal signal; generate a group of de-skew values based on at least a portion of the skew values; and transmit the de-skew values, to the optical receiver, where transmitting the de-skew values allows the optical receiver to de-skew signals on the group of channels.

Abstract: The present invention provides optical power adjustment method for EPON system, and OLT. The method comprises: OLT starting optical power adjustment procedure after ONU or ONT successfully registers, receiving upstream data from the ONU or the ONT (201); during optical power adjustment procedure, OLT detecting whether there is error code in upstream data; if not, notifying the ONU or the ONT to decrease transmission optical power progressively, during progressive decrease procedure, OLT continuing to detect whether there is error code in upstream data (203); if there is error code during progressive decrease procedure, notifying the ONU or the ONT to increase transmission optical power progressively, and during progressive increase procedure, OLT continuing to detect whether there is error code in upstream data (205); if there is no error code during progressive increase procedure, OLT stopping the adjustment (207).

Abstract: A position in which an optical signal characteristic is compensated in an optical network can be chosen. An optical network equipment measures an optical signal characteristic for each wavelength, and notifies an optical network equipment on a communication path of an optical signal characteristic index and control necessity determination threshold. In an upstream portion of the communication path, the optical network equipment (a start point or the like of the communication path) that can compensate the optical signal characteristic for each wavelength determines the necessity to eliminate a deviation between wavelengths and the position to eliminate it, using the optical signal characteristic index and the control necessity determination threshold.

Abstract: An optical packet switching apparatus includes an optical coupler for branching off a received optical packet signal, an optical switch unit for switching the route of one of the branched-off optical packet signals so as to be outputted, and an optical switch control unit for controlling the optical switch unit. The optical switch control unit includes an optical-to-electrical conversion unit for converting the other of the branched-off optical packet signals into an electrical packet signal, a serial/parallel conversion unit capacitively coupled to the optical-to-electrical conversion unit, a packet density detector for detecting the packet density of the received packet signal, and a DC offset adjustment unit for adjusting the DC offset voltage of the packet signal, inputted to the serial/parallel conversion unit, according to the packet density information detected by the packet density detector.

Abstract: An intelligent optical module to restart itself according to a command sent from the host system is disclosed. The optical module may distinguish the first state, where no optical signal is received, from the second state, where a substantial optical signal but unmodulated is received. The optical module is restarted when the second state appears with a preset pattern.

Abstract: A method and device for performing skew detection on data transmitted over a data channel and a high speed optical communication interface including the device are disclosed, wherein data of a reference frame over a reference channel is composed sequentially of a reference data segment with a length of Umax over each of data channels to be subject to skew detection.

Abstract: A WDM transmission apparatus to receive or relay WDM light in a WDM transmission system, includes a measuring unit configured to measure an optical level of each channel transmitted by the WDM light; an adjusting unit configured to adjust a resolution of the measuring unit; and a processing unit configured to obtain, for each channel, optical level information which represents an optical level respectively measured with a resolution corresponding to a bit rate of a transmission signal of each channel.

Abstract: The disclosed methods and apparatuses provide a unique and cost efficient approach to using traffic channels of an optical mesh network, and sometimes optical supervisory channels, for carrying timing information (e.g., BITS timing signals), thus eliminating the need to use external BITS sources at remote add/drop nodes of a network. Planning the distribution of timing in such an optical mesh network includes identifying in the network a source node associated with an external timing source, identifying optical light paths between nodes in the network, and, for nodes other than the source node, selecting optical light paths originating either directly or indirectly from the source node to use to derive timing information.

Abstract: A digital coherent receiver includes a sampling phase detector to detect a phase of a sampled digital signal, and a phase adjustor to adjust the sampling phase of the digital signal based upon the detected phase. The phase detector includes filters to equalize the digital signal with different equalization characteristics; sensitivity monitoring phase detectors, each connected to one of the filters and outputting a phase detection signal representing the phase of the output signal from the associated filter together with a sensitivity monitoring signal representing the sensitivity of the phase detection; sensitivity correction coefficient generators, each generating a sensitivity correction coefficient for correcting the associated phase detection signal using a square sum of the sensitivity monitoring signals; and an adder to add the phase detection signals that have been corrected by the sensitivity correction coefficients, and output a phase signal.

Abstract: An example is a bandwidth control method employed in an optical line terminal including: determining a first time point at which a first optical network unit starts the processing of transitioning between the states in a case where the first optical network unit is to be transitioned between the states; transmitting a state control signal containing the first time point to the first optical network unit in order to control the first optical network unit to start the processing of transitioning between the states; and stopping allocating a bandwidth used to transmit a signal to the optical line terminal to a second optical network unit during a period from the first time point until it is determined that the first optical network unit has finished the processing of transitioning between the states.

Abstract: A method for optically transmitting data between a transmitter and a receiver is provided, wherein a color coding method based on a plurality of elementary colors is provided for encoding and transmitting the data, wherein each elementary color is transmitted by a transmitter-side optical radiation source and is received on the receiver side by an optical radiation receiver. The method includes transmitting a training request message comprising calibration information formed on the transmitter side; forming a channel properties matrix by the receiver from the calibration information and storing the channel properties matrix in the receiver; calculating at least one compensation information on the basis of a reference channel properties matrix stored in the receiver and the reference channel properties matrix; and transmitting the compensation information from the receiver to the transmitter.

Abstract: A signal strength corresponding to an incoming optical burst from each of a plurality of optical nodes is measured. The measurements can be performed at system start-up, configuration/installation of the optical nodes and/or at certain intervals of operation of the optical nodes. Signal strength information for the optical nodes based on the measurements is stored in memory. When scheduling the optical nodes for transmission, a preferred transmission order is determined in response to the stored signal strength information. In an embodiment, the preferred order is determined to reduce differences in signal strength levels between consecutive optical bursts.

Abstract: An approach for saving power in a fiber ports of a network system is provided. An instance of a period of inactivity for a fiber port of the network system is determined. Power delivery to a transmit laser of an SFP (small form-factor pluggable) device of the fiber port is terminated during at least a portion of the period of inactivity. Power delivery to the SFP device is maintained while power delivery to the transmit laser is terminated.

Abstract: A method for estimating optical power in an optical channel includes determining a tunable filter full-width, FWF, by measuring a response of the tunable filter to a known signal and mapping the response to frequency. A portion of an optical channel is coupled to an input of the tunable optical filter. A peak power response, PR, and a full width tunable filter response, FWR, to the optical channel are determined by measuring a response of the tunable filter to the optical channel and mapping the response to frequency. A signal power, PS, is then calculated from the peak power response, PR, and a ratio of the full width tunable filter response, FWR, to the tunable filter full-width, FWF.

Abstract: In one embodiment, a method includes receiving a first input stream, generating a first clock, sampling the first input stream based on the first clock, detecting a first phase difference between the first input stream and the first clock to generate a clock-correction signal and a first select signal, and generating a first recovered stream based on the first select signal. The method may additionally include receiving a second input stream, generating a second clock, sampling the second input stream based on the second clock, detecting a second phase difference between the second input stream and the second clock to generate a clock-correction signal and a second select signal, and generating a second recovered stream based on the second select signal. The method may further include adjusting the clocks based on the first and second clock-correction signals and combining the first and second recovered data streams to generate an output.

Abstract: Digital timing error detection systems and techniques are described. The described techniques are independent of polarization and differential-group-delay and are used to perform timing recovery of polarization-multiplexed coherent optical systems.

Abstract: A method, system and computer-usable medium are disclosed for visually indicating the remaining life of a small form factor pluggable (SFP) optical transceiver module. The total number of optical light pulse signals processed by an SFP are compared to a predetermined lifecycle number of signals that can be processed before the SFP enters a failed operating state. The remaining life of the SFP is calculated. A first display visually indicates that the total number of processed signals has not exceeded the lifecycle number of signals. A second display located on the SFP enclosure visually indicates the SFP has reached the end of its lifecycle.

Abstract: A method comprising identifying a data demand of an optical channel request; identifying available resources for satisfying the optical channel request; selecting light paths to a destination based on the identified available resources, wherein each light path is distinct; selecting one or more optical carriers for each light path; optically transmitting data pertaining to the optical channel request based on the selected light paths, wherein each selected optical carrier of each light path carries a portion of the data and a total of the one or more optical carriers associated with the light paths collectively carry an entire portion of the data; receiving the one or more optical carriers of the light paths at the destination; identifying a latency between the one or more optical carriers of the light paths; adjusting the latency between the one or more optical carriers of the light paths; and assembling the data.

Abstract: A method removes signal interference in a passive optical network. The passive optical network includes an optical line terminal, a splitting unit coupled with the optical line terminal, an optical network unit coupled with the splitting unit, and an identification signal uniquely associated with the optical network unit. The method includes the steps of sending a first signal, detecting the first signal, comparing the detected first signal with an identification signal and decoupling the optical network unit from the splitting unit if the comparing step results in a mismatch.

Abstract: The invention provides an optical burst switch in an Optical Burst Switched (OBS) communication network, said optical burst switch comprising means for monitoring and maintaining mesh of virtual optical paths from a communication node to a plurality of other communication nodes, arranged in a ring network, enabling traffic data to be transmitted and/or received between nodes via a physical optical path. The switch also provides means for sending a data packet probe on a virtual path from a node to each other node in the OBS communication network, wherein data packet probe information received at said switch provides information of availability of the physical optical path for sending traffic data between nodes. The switch can be configured such that the rate at which this path monitoring is scheduled guaranteeing less than 50ms protection switch in the event of monitoring a failed or degraded path.