A transmission apparatus includes: a generator configured to generate position information indicating a position of header information of each of a plurality of first signals from a second signal nesting the plurality of first signals; a storage configured to store the position information generated by the generator and the plurality of first signals; a monitor configured to read the position information and the plurality of first signals stored in the storage, and to monitor the header information of each of the plurality of first signals based on the position information; and an output unit configured to output the plurality of first signals after monitoring the contents of the header information.

A transmission device includes a receiver configured to receive a frame signal including synchronization data, main signal data, and an error correction code, a compensator configured to compensate for distortion of the frame signal based on a compensation coefficient, a detector configured to detect synchronization timing of the frame signal from the synchronization data; a corrector configured to correct an error of the frame signal after the distortion is compensated, based on the error correction code according to the synchronization timing, a generator configured to generate a replica signal from the frame signal after the error is corrected by the corrector, based on the synchronization timing, the replica signal corresponding to the frame signal before the distortion is compensated, and an update processor configured to update the compensation coefficient based on the replica signal and the frame signal before the distortion is compensated.

Embodiments describe monitoring network activity and behavior of authorized clocks to identify suspicious activity, and in response, removing a clock for an authorized clock list. In one embodiment, a network monitor detects changes in profiles corresponding to the authorized clocks such as a disconnecting from a port, changing a network location, unexpected changes in the clock signal, changes to the clock ID or MAC address, and the like. If the network monitor deems these changes suspicious, it removes the clock from the authorized clock list. When the current master clock fails, the PTP endpoints select a new master clock only if that clock is included in the authorized clock list. In this manner, the network monitor can constantly update the authorized clock list to ensure it contains only clocks that have not been tampered with or replaced with rogue clocks.

An embodiment of this application provides a data transmission method. The method includes: A first communication apparatus sends an i.sup.th AM group to a second communication apparatus, and sends first data of a plurality of service flows to the second communication apparatus based on a mapping relationship. The first data is carried in M time units between the i.sup.th AM group and an (i+1).sup.th AM group, the mapping relationship is a mapping relationship between a slot of a first calendar and the plurality of service flows, and the first calendar includes s slots. The M time units between the i.sup.th AM group and the (i+1).sup.th AM group include N first counting periods, each time unit of the first counting period corresponds to one slot of the first calendar, and different time units of a same first counting period correspond to different slots of the first calendar.

One embodiment of the present invention sets forth a technique for performing time synchronization within a network. The technique includes receiving, from a first node in the network and at a first receive time, a first periodic beacon that includes a first network time associated with the first node. The technique also includes determining a second receive time at which a second periodic beacon from the first node is to be received based on the first network time and the first receive time. The technique further includes calculating a first listening window for the second periodic beacon based on the second receive time, a first jitter uncertainty, and a first drift uncertainty, and listening for the second periodic beacon during the first listening window.

A communication system includes a master device and a plurality of slave devices. Each slave device stores a synchronization period and a correction amount of a difference between a time of the master device and a time of the slave device. The master device acquires the correction amount from the slave device, calculates a correspondence relationship between a synchronization period and the correction amount based on the correction amount, calculates a target synchronization period in the slave device based on the correspondence relationship, classifies each slave device into a plurality of groups based on the target synchronization period in each slave device, and sets a maximum target synchronization period among the target synchronization periods of at least one slave device classified into each group to a new synchronization period in which the master device performs the time synchronization along with the at least one slave device.

Techniques for performing time synchronization within a network include a method comprising: determining, by a first node, a receive time at which a periodic beacon from a second node is expected to be received based on timing information associated with the second node; determining, by the first node, a first listening window for the periodic beacon based on the receive time and one or more of a drift uncertainty associated with an anticipated drift in a correction of a timing error between the first node and the second node or a jitter uncertainty associated with timing jitter in the first node or the second node; and listening, by the first node, for the periodic beacon during the first listening window.

A first network element includes trail trace identifier information in an optical network frame. The first network element obtains data to transmit over an optical network link to a second network element. The first network element generates an optical network frame with alignment marker bytes, which are followed by padding bytes. The optical network frame also includes overhead bytes following the padding bytes. The overhead bytes include a Multi-Frame Alignment Signal (MFAS) byte, a link status byte, and reserved bytes. The optical network frame also includes a payload bytes following the overhead bytes. The payload bytes encode at least a portion of the data to transmit to the second network element. The first network element inserts trail trace identifier information into the reserved bytes in the overhead bytes. The trail trace identifier information identifies the first network element as a source of the optical network frame.

Examples relate to communicating synchronization information from a satellite to a power supply device to enable time synchronization between the satellite and the power supply device. The power supply device includes a port to receive, from a modulator, a modulated current corresponding to a power consumption across a dummy load, where a level pattern of the modulated current indicates the synchronization information received from the satellite. The power supply device includes a power consumption analyzer configured to receive a modulated voltage, across a shunt resistor, corresponding to the modulated current and recover, from the modulated voltage, the synchronization information.

A communication system includes a master device and a plurality of slave devices. Each slave device stores a synchronization period and a correction amount of a difference between a time of the master device and a time of the slave device. The master device acquires the correction amount from the slave device, calculates a correspondence relationship between a synchronization period and the correction amount based on the correction amount, calculates a target synchronization period in the slave device based on the correspondence relationship, classifies each slave device into a plurality of groups based on the target synchronization period in each slave device, and sets a maximum target synchronization period among the target synchronization periods of at least one slave device classified into each group to a new synchronization period in which the master device performs the time synchronization along with the at least one slave device.