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

S9300, S9300E, and S9300X V200R012C00

This document describes the configurations of Device Management, including device status query, hardware management, CSS, SVF, PoE, OPS, OIDS, energy-saving management, information center, fault management, NTP, synchronous ethernet, PTP.
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).
CSS Setup

CSS Setup

A CSS is set up automatically after you use cluster cables to connect two switches, enable the CSS function on the two switches, and restart the switches. The member switches then send CSS competition packets to each other. After these packets are received, role election takes place, and one switch becomes the master switch to manage the CSS, with the other becoming the standby switch.

Role Election

The master switch of a CSS is elected based on the following rules:
  1. The switch that starts and enters the single-chassis CSS state first becomes the master switch.

  2. If the two switches start at the same time, the switch with a higher CSS priority becomes the master switch.

  3. If the two switches start at the same time and have the same CSS priority, the switch with a smaller MAC address becomes the master switch.

  4. If the two switches start at the same time and have the same CSS priority and MAC address, the switch with a smaller CSS ID becomes the master switch.


If the master switch is elected because it starts and enters the single-chassis CSS state first, the other joins the CSS according to New Member Joining and CSS Merging.

The master MPU on the master switch works as the system master MPU, managing the CSS. The master MPU on the standby switch works as the system standby MPU. The standby MPUs of the master and standby switches work as candidate system standby MPUs. Figure 3-5 shows the role election process and result after a CSS is set up. In this example, SwitchA is elected as the master switch.

Figure 3-5  Role election result in a CSS

Software Version Synchronization

CSS technology provides an automatic software loading mechanism. Member switches do not have to run the same software version, and they can set up a CSS as long as their software versions are compatible with one another. If the software version running on the standby switch is different from that on the master switch, the standby switch downloads the system software from the master switch, restarts with the new system software, and joins the CSS again.

Configuration File Synchronization

CSS technology uses a strict mechanism to synchronize configuration files. This mechanism ensures that CSS member switches function as a single switch.

  • When the standby switch starts, it synchronizes its configuration file with the master switch.
  • When CSS is running, all the configurations performed by users are recorded in the configuration file of the master switch and synchronized to the standby switch.

The configuration file synchronization mechanism ensures that the member switches save the same configuration file. If the master switch fails, the standby switch takes over all services using the same configuration file. After the CSS splits, the configuration of the master switch is not lost even if it is not saved in a timely manner, and the CSS becomes two single-chassis CSSs with the same configuration. In this situation, if a member switch restarts, its unsaved configuration is lost. For details about a CSS split, see CSS Split and MAD.

Configuration File Backup

After a switch enters the CSS state, it automatically backs up its configuration file used in standalone state by adding the file name extension .bak to the configuration file name. For example, if the original configuration file name extension is .cfg, the backup configuration file name extension is .cfg.bak. In this way, the switch can restore the previous configuration after the CSS function is disabled.

If you want to restore the original configuration of a switch after disabling the CSS function, delete the file name extension .bak from the backup configuration file name, specify this configuration file for next startup, and then restart the switch.

Updated: 2018-09-03

Document ID: EDOC1100038289

Views: 43705

Downloads: 15

Average rating:
This Document Applies to these Products
Related Version
Related Documents
Previous Next