Systems and methods of compensating for the delay asymmetry of coherent optical modems in a packet optical network include measuring fill levels of one or more queues each including an elastic First-In-First-Out (FIFO) circuit used in a transport mapping scheme, wherein the transport mapping scheme is one or more of client mapping to Optical Transport Unit (OTU) and OTU mapping to Flexible OTN (FlexO); and performing adjustments in a clock based in part on the measured fill levels, wherein the adjustments are configured to reduce a Time Error (TE) in the packet network based on delay asymmetry between two nodes.

Systems and methods of compensating for the delay asymmetry of coherent optical modems in a packet optical network include measuring fill levels of one or more queues each including an elastic First-In-First-Out (FIFO) circuit used in a transport mapping scheme, wherein the transport mapping scheme is one or more of client mapping to Optical Transport Unit (OTU) and OTU mapping to Flexible OTN (FlexO); and performing adjustments in a clock based in part on the measured fill levels, wherein the adjustments are configured to reduce a Time Error (TE) in the packet network based on delay asymmetry between two nodes.

Methods, systems, and media for presenting contextually relevant information are provided. In some implementations, the method includes: receiving information associated with a user of a user device from multiple data sources, where the user device comprises a display; identifying, without user intervention, a relevant document based on the received information associated with the user of the user device; determining that a new browser window or a new browser tab has been opened by a browser application being executed by the user device; and causing, without user intervention, the relevant document to be presented using the new browser window or new browser tab.

In a method, a network device receives a combined optical signal, where the combined optical signal is obtained by coupling optical signals sent by a plurality of communication nodes. If the network device is not a master node, the network device detects whether a master label exists in the combined optical signal, where the master label indicates the master node. If it is detected that a first master label exists in the combined optical signal, where the first master label indicates a first master node, the network device synchronizes a local clock frequency with a clock frequency of the first master node.

Provided are a method and a device for implementing timeslot synchronization. The method includes: a master node performing timeslot synchronization training of an OBTN according to a timeslot length of the OBTN. By adopting the solution provided by the embodiments of the present disclosure, an FDL does not need to be considered in node design, the node design is simplified, the time precision of synchronization is improved and no loss is caused to optical efficiency.

The present disclosure provides a data transmission method and apparatus, a network device, a system, and a storage medium. The data transmission method includes: continuously sending downlink data frames of different rates at a first designated wavelength in a time-division multiplexing manner, with the downlink data frames carrying clock recovery information and time slot identification information of the downlink data frames of the different rates; and the clock recovery information is used for an optical network unit to perform clock recovery on the downlink data frames of the different rates, and the time slot identification information is configured to indicate time slot information of the downlink data frames of the different rates at the first designated wavelength.

In the optical transport system a transport frame generator divides a transport frame accommodating plural client signals into plural transmission signals. Subcarrier transmission units convert the signals into optical signals using different optical carriers and transmit the converted optical signals. Subcarrier reception units receive the transmitted optical signals and convert the optical signals into reception signals. A transport frame termination unit combines the reception signals to restore the transport frame. A time-demultiplexing processor time-demultiplexes the restored transport frame to be separated into the client signals. A time slot control unit determines a new time slot allocation when time-multiplexing the client signals in the transport frame and stops supply of electric power to a subcarrier transmission unit and a subcarrier reception unit that transmit and receive an optical signal to which the client signals are not allocated.

A holdover mode device is illustrated. When a time synchronization source is not abnormal, a digital PLL uses a time synchronization source as its input clock, and a measurement and adjustment module calculates a variation of a frequency difference between the time synchronization source and a reference clock output by an adjustable oscillator, and builds a frequency difference prediction model according to the variation of the frequency difference. When the time synchronization source is abnormal, the digital PLL uses a buffered time synchronization source as its input clock, and the measurement and adjustment module uses the frequency difference prediction model to calculate a predicted variation of the frequency difference according to buffered frequency difference values, and generates an adjustment signal for adjusting the reference clock according to the predicted variation of the frequency difference.

The present disclosure discloses a method for remotely configuring a Precision Time Protocol PTP service of an Optical Network Unit ONU. The method includes: after an ONU performs an initialization, the ONU creates a PTP management entity; the ONU receives a PTP management entity attribute sent by an OLT and set by the OLT; and the ONU parses the PTP management entity attribute sent by the OLT and sets a corresponding PTP service according to the PTP management entity attribute. The present disclosure further discloses an ONU, an OLT and a system corresponding to the method.

A data processing device includes: a FIFO buffer; a write circuit writing data in the buffer according to a write clock signal; a read circuit reading data from the buffer according to a read clock signal, a PLL circuit conducting a phase synchronization processing of the read clock signal based on a phase difference between the write and read clock signals and outputting a notification signal when the phase difference becomes within a predetermined range; a write control circuit controlling a timing when the write circuit starts writing based on the notification signal; a read control circuit comparing an address in which data is written and a reference address and controlling a timing when the read circuit starts reading based on a comparison result; and a correction circuit correcting the reference address with a value corresponding to the phase difference obtained when the notification signal has been output.