A method of synchronization of a communication device comprising a first and second communication ports, each of the first and second communication port being associated with a respective first and second time system, the method comprising a regular master synchronization process synchronizing regularly the first time system with an external synchronization server according to a time synchronization protocol; a regular slave synchronization process synchronizing regularly the second time system with the first-time system; detecting a loss of synchronization between the first and second time system; determining which of the first and second time system is desynchronized; and synchronizing the desynchronized time system with the other one.

[Problem] It is possible to improve the quality of time information by suppressing a jump in time which arises when switching a transfer path in a BC apparatus to which transfer paths of time information of at least 2 systems are connected to an input side. [Solution] A time synchronization apparatus 20 is mounted on a BC apparatus 12c in which two systems of at least a 0-system route (0-system) and a 1-system route (1-system) are connected to an input side, and includes a time correction value holding unit 26 configured to hold a 0-system correction value in which a time error resulting from delay of UTC due to performance inherent to the BC apparatus is the same value as a time error accumulated on the 0-system side and a 1-system correction value in which the time error is the same value as a time error accumulated on the 1-system side. Further, a failure restoration detection unit 23 configured to detect a failure in the 0-system or the 1-system, a time calculation unit 24 configured to perform correction by subtracting a 1-system correction value relating to a normal 1-system from UTC having time error accumulated on the normal 1-system side, when a failure in the 0-system is detected, and a path switching unit 25 configured to switch to the normal 1-system side such that the UTC after correction is transferred, when the failure is detected, are included.

Continuance in quality level of an input timing signal may be provided. Clock source reference timing information may be receive by a first node from a second node as an input. The first node may be downstream from the second node. Then the first node may receive an event message associated with a future event associated with the second node. The first node may then refrain, for a period of time in response to receiving the event message, from switching the input for clock source reference timing information to a source other than the second node.

A method for switching clock sources is provided. In the method, Precision Time Protocol, PTP, packets are monitored using each of PTP ports which connect to a new grandmaster (401). A frequency and a phase for the PTP port are calculated based on the PTP packets (402). In response to a successful check for the frequency and the phase, the PTP port is added to a candidate list (403). A phase calibration and a phase stability check may be introduced prior to the alternate BMCA.

A method includes receiving, by a first node on a first port of the first node, a first packet from a second node; and when the first packet carries a first flag, avoid selecting, by the first node and when selecting a clock source, a clock source corresponding to the first port, where the first flag indicates that time synchronization of the second node is uncertain.

In some embodiments, a first computing device detects a loss of a connection to a first source of timing information that the first computing device and a second computing device use to maintain synchronization with a first clock and a second clock. The first computing device receives a second source of timing information from the second computing device. The second source of timing information is also being transmitted to a third computing device. The first computing device uses the second source of timing information to determine a first timestamp and determines a second timestamp from the first clock. The first computing device uses the first timestamp and the second timestamp to adjust a rate of the first clock where the first clock is used to transmit the second source of timing information from the second computing device to the third computing device.

In a wireless communication system including a plurality of wireless base stations, the wireless base stations other than the uppermost wireless base station among the plurality of wireless base stations each determine a frame timing on the basis of synchronization timing information received from the upper wireless base station, and the wireless base stations other than the lowermost wireless base station among the plurality of wireless base stations each notify the lower wireless base station of the synchronization timing information. A communication path from the uppermost wireless base station to the lowermost wireless base station includes a branch point and a merge point, and a junction base station that is the wireless base station installed at the merge point measures a synchronization error between a priority synchronization path and a non-priority synchronization path different from the priority synchronization path, the priority synchronization path being one of a plurality of the communication paths from the branch point to the merge point. Each of the plurality of wireless base stations installed on the non-priority synchronization path adjusts the frame timing on the basis of the synchronization error.

A network device synchronization method is provided. In various embodiments, a first SSM and a second SSM are received. The first SSM carries a first SSM code indicating a quality level of a first clock source and a first eSSM code indicating the quality level of the first clock source, the second SSM carries a second SSM code indicating a quality level of a second clock source. The second SSM lacks an eSSM code indicating the quality level of the second clock source, and a value of the first SSM code is equal to a value of the second SSM code. When a value of the first eSSM code is less than 0xFF, calibrating a frequency of the network device based on a timing signal of the first clock source.

Systems and methods for providing timing information from a R-MACHPHY device to a video core while the R-MACPHY device receives video data from the video core while operating in asynchronous mode. In some embodiments, the R-MACPHY device may alternately and selectively configure its mode of operation to alternate between synchronous mode and asynchronous mode, and provide the timing information to the video core when it switches to asynchronous mode.

Provided are a method of synchronizing a communication network, the method comprising obtaining a quality parameter of at least two or more synchronization sources connected to communication nodes in a communication network and a capacity parameter of the communication nodes connected to the synchronization sources, selecting a synchronization source to be used for synchronization of the communication network from among the at least two or more synchronization sources, according to a priority based on the obtained quality parameter and capacity parameter and performing synchronization of the communication network using a synchronization signal provided from the selected synchronization source.