status information or system alarm information. After clock source is determined, the
system uses high-precision clock at the Ethernet interface to send data and transfer
synchronization status information, synchronizing Ethernet physical-layer E2E data
transceiving. Its synchronization mode is shown as Figure 3-12.
Figure 3-12 SyncE synchronization
3.6.3 IEEE 1588 v2
IEEE 1588 v2 is a precision time synchronization protocol, called PTP protocol for short.
IEEE 1588 v2 adopts master/slave clock to transport time in the form of code. Time
stamp is generated at the protocol layer adjacent to the physical layer. It uses symmetry
and delay measurement technology of network link to synchronize frequency, phase and
absolute time of master/slave clock. 1588 key lies in delay measurement.
IEEE 1588 v2 master/slave clock synchronization principle is shown in Figure 3-13: Slave
clock synchronizes with master clock through offset measurement, and then delay
measurement is made to get inter-clock link delay and time deviation to adjust time
output of slave clock and synchronize the time between master clock and slave clock.
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