Ptp Overview - Huawei Quidway S9300 Configuration Manual

Quidway S9300 Terabit Routing Switch
Configuration Guide - Device Management

12.1 PTP Overview

Definition of synchronization
In a modern communications network, the proper functioning of most telecommunications
services requires that the frequency offset or time difference between devices be kept in a
reasonable range. This is the network's requirement for clock synchronization. Network clock
synchronization consists of phase synchronization and frequency synchronization.
l
l
Figure 12-1 Schematic diagram of phase synchronization and frequency synchronization
Figure
synchronization. In phase synchronization, Watch A and Watch B always keep the same time,
whereas in frequency synchronization, Watch A and Watch B keep different time, but the time
difference between the two watches is a constant value, for example, six hours.
Issue 03 (2011-12-29)
Frequency Synchronization
Frequency synchronization refers to strict relationship between signals based on a constant
frequency offset or phase offset, in which signals are sent or received at a rate in an epoch.
In this manner, all devices in the communications network operate at the same rate. That
is, the difference of phases between signals is a constant value.
Phase Synchronization
Phase synchronization refers to consistency of both frequencies and phases between
signals. That is, the phase offset between signals is always 0.
Watch A
Watch B
Watch A
Watch B
12-1shows the difference between phase synchronization and frequency
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
Phase synchronization
Frequency synchronization
12 PTP Configuration
204