Synchronization of clocks among computing devices in a network includes determining master/slave relations among the computing devices. Some computing devices (e.g., switches) include trunk ports configured to carry traffic for several logical networks; e.g., virtual local area networks, VLANs. A trunk port can be associated with a master/slave setting for each logical network that it is configured for. Synchronization of clocks among the computing devices further includes running a synchronization sequence between a trunk port and each computing device on each of the logical networks configured on the trunk port.

The precision time protocol (PTP) runs on the peer switches in an MLAG domain. PTP messages received by one peer switch on an MLAG interface is selectively peer-forwarded to the other peer switch on the same MLAG interface in order to coordinate a synchronization session with a PTP node. The peer-forwarded messages inform one peer switch to be an active peer and the other peer switch to be an inactive peer so that timestamped messages during the synchronization session are exchanged only between the PTP node and the active peer, and hence take the same data path.

In a hybrid network comprising both guided and wireless communications technologies, a grandmaster clock is designated in one portion of the network and can be propagated across to the other portion by means of a timing synchronization message. This message may include timestamping information and other information to enable recipient devices to correctly synchronize to the grandmaster clock.

A system includes a plurality of line cards and a timing card. A clock generation circuit on the timing card generates a clock signal which is pulse width modulated according to information to be transmitted. A clock line supplies the pulse width modulated clock signal to the line cards. The timing card sends a first control word to the plurality of line cards over the clock line after sending a beacon. The first control word includes a size field specifying a first length of first data following the first control word. The timing card sends time of day information over the clock line to the line cards following the first control word. The time of day information may be encrypted. A second control word follows the time of day information. One or more additional control words can follow the second control word before the next beacon.

An example method includes creating, by a computing system and in response to user input, one or more virtual master devices and a plurality of virtual leaf devices in a virtual network system; selecting, by the computing system, data from one or more of real-time clock offset data, prerecorded clock offset data, or synthetically generated clock offset data; executing, by the computing system, a time synchronization simulation by applying a predefined clock offset generation algorithm to the selected data; and outputting, by the computing system, data indicative of results of the time synchronization simulation.

A time synchronization method, a time synchronization sender, a time synchronization receiver and a time synchronization system are provided. The method includes: determining whether at least one parameter causing recalculation of a best master clock (BMC) algorithm changes; in a case where it is determined that the parameter changes, sending a 1588 standard-based Announce message; and in a case where it is determined that the parameter does not change, sending a keep-alive message of the Announce message. In the present disclosure, by distinguishing keep-alive messages from protocol messages, the problem that a CPU system is busy due to the processing of Announce messages is solved, thereby realizing the optimization of the 1588 protocol, and reducing the impact on the CPU.

Provided is a method for providing a time synchronization service for an external application service of a 5G system (5GS). A method may include: receiving, by a Network Exposure Function (NEF) from an Application Function (AF), a request for a capability for a 5GS time synchronization service; and in response to the request for the capability, transmitting, by the NEF to the AF, a time synchronization parameter including the capability.

An example system comprising a first transceiver configured to receive a request airframe from a second transceiver over a wireless link, the request airframe including a first time indication indicating a first time TS1, a second time indication indicating a second time TS2 that the request airframe was received, generate a respond airframe and including a third time indication indicating a third time TS3 that the respond airframe is transmitted to the second transceiver, transmit the respond airframe to the second transceiver, provide a timestamp information request to second transceiver, receive a timestamp information response, the timestamp information response including a fourth time indication indicating a fourth time TS4, calculate a counter offset using the first time, second time, third time and fourth time as follows:

[00001]$\mathrm{counter}\mathrm{offset}=\frac{\left(\mathrm{TS}1+\mathrm{TS}4-\mathrm{TS}3-\mathrm{TS}2\right)}{2},$

calculate a phase offset based on the counter offset, and correct a phase of the first transceiver.

Synchronization of clocks among computing devices in a network includes determining master/slave relations among the computing devices. Some computing devices (e.g., switches) include trunk ports configured to carry traffic for several logical networks; e.g., virtual local area networks, VLANs. A trunk port can be associated with a master/slave setting for each logical network that it is configured for. Synchronization of clocks among the computing devices further includes running a synchronization sequence between a trunk port and each computing device on each of the logical networks configured on the trunk port.

A network device may assign, to a port of a plurality of ports on the network device, a precision timing protocol (PTP) port priority for PTP communications between the network device and another network device. The network device and the other network device may be communicatively connected via a plurality of links in a link aggregation group (LAG). Each port, of the plurality of ports, may be associated with a respective link, of the plurality of links, in the LAG. The network device may generate a link layer discovery protocol (LLDP) frame that includes information identifying the PTP port priority assigned to the port. The network device may transmit the LLDP frame to the other network device to identify, to the other network device, the PTP port priority.