No relevant resource is found in the selected language.

This site uses cookies. By continuing to browse the site you are agreeing to our use of cookies. Read our privacy policy>Search


To have a better experience, please upgrade your IE browser.


Configuration Guide - Device Management

CloudEngine 12800 and 12800E V200R003C00

This document describes the configurations of Device Management, including device status query, hardware management, Information Center Configuration, NTP, Synchronous Ethernet Configuration, Fault Management Configuration, Energy-Saving Management Configuration, Performance Management Configuration, Maintenance Assistant Configuration, and OPS Configuration.

Rate and give feedback:
Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).
Configuring Automatic Clock Source Selection

Configuring Automatic Clock Source Selection


A switch supports three clock source selection modes: automatic, manual, and forcible modes. By default, a switch works in automatic clock source selection mode.

The clock source priority and Synchronous Status Message (SSM) quality level are the factors in selecting the clock source:
  • Clock source priority

    A clock source does not have a default priority and does not participate in clock source selection by default. To enable a clock source to participate in clock source selection, specify a priority for it.

    A smaller priority value indicates a higher priority.

  • Clock source SSM quality level

    An SSM is a group of codes that indicate the clock quality level on a synchronization network. SSM directly reflects the level of a synchronous timing signal transmitted on a synchronous timing link. A higher clock accuracy indicates a higher SSM quality level. You can determine whether to enable a switch to select the clock source based on the SSM quality level.

    SSM quality levels are Primary Reference Clock (PRC), Transit Node Clock (SSU-A), Local Node Clock (SSU-B), SDH Equipment Clock (SEC), Unknown (UNK), and Do Not Use (DNU) in descending order.

When multiple clock sources are available on the network, a switch selects the clock source according to the following rules:
  1. If no SSM quality level is specified for clock source selection, the switch selects the clock source to trace based on the priorities configured for the clock sources.
  2. If an SSM quality level is specified for clock source selection:
    1. The switch selects the clock source to trace based on the SSM quality levels of clock sources.
    2. If there are multiple clock sources with the same SSM quality level, the switch selects the clock source to trace based on the priorities of these clock sources.


  1. Run system-view

    The system view is displayed.

  2. (Optional) Run clock clear [ 2msync-1 | 2msync-2 ]

    The clock source selection mode is restored to the automatic mode.

    You can run this command to restore the clock source selection mode from manual or forcible to automatic clock source selection.

  3. (Optional) Run clock ssm-control on

    SSM quality levels are used for automatic clock source selection.

    By default, SSM quality levels are not used for clock source selection.

  4. Run clock run-mode normal

    The system clock running mode is set to the normal mode.

    By default, the system clock works in normal mode.

  5. Run commit

    The configuration is committed.

Updated: 2019-05-05

Document ID: EDOC1100004193

Views: 70863

Downloads: 26

Average rating:
This Document Applies to these Products

Related Version

Related Documents

Previous Next