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S12700 V200R010C00 Configuration Guide - Device Management

This document describes the principles and configurations of the Device Management features, and provides configuration examples of these features.
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Upgrading CSS Software

Upgrading CSS Software


Two methods are available to upgrade CSS software: system restart and quick upgrade.

Table 8-8  Comparison of system restart and quick upgrade
Upgrade Method Command Application Scenario Role Change After the Upgrade

System restart


The system restart method is frequently used. This upgrade method causes service interruption for a relatively long period of time and is appropriate for use in scenarios insensitive to the service interruption time.

The switch with a higher CSS priority becomes the master switch. If switches have the same CSS priority, the switch with a smaller MAC address becomes the master switch.

Quick upgrade

css fast upgrade

The quick upgrade minimizes the impact of the upgrade on services. This upgrade method is appropriate for use in scenarios sensitive to the service interruption time.

You are advised to bundle CSS uplinks and downlinks into Eth-Trunks for link redundancy. Otherwise, data traffic may be interrupted for several minutes based on the service deployment.

  • The original standby switch becomes the master switch.

  • The original master switch becomes the standby switch.

During a quick upgrade, if one of the following situations occurs, the upgrade will fail and then the system automatically finishes version and patch rollback:
  • Boards do not register for a long period during the upgrade of the standby chassis.
  • Configurations cannot be restored or backed up in a batch for a long period during the upgrade of the standby chassis.
  • The standby chassis has no MPU installed, and the master chassis forcibly exits from the quick upgrade. If the standby chassis has MPUs installed, the standby chassis will enter the single-chassis CSS state, perform version and patch rollback, and join the CSS again.
To view information about preceding quick upgrade failures, check the log CSSM/6/FASTUPGRADEROLLBACK.

If the quick upgrade fails, the standby chassis will roll back to the old version and start, enter the single-chassis CSS state, restart and then join the CSS after the boards on the standby chassis register. The rollback process lasts at most 1 hour. During the rollback, ports and services on the master chassis will be working normally, and the ports on the standby chassis will remain Down. During the rollback, do not perform operations on the standby chassis hardware, for example, install, remove, reset, or power off the boards on the standby chassis.


  1. Load the new system software version to the master MPU of the CSS. For details on how to load the file, see File Management in the S12700 V200R010C00 Configuration Guide - Basic Configuration.
  2. Run the startup system-software system-file all command to configure the software file name all the MPUs use for next startup.

    In this process, the system software is copied from the CSS master MPU to all the MPUs.

  3. Run the reboot command to upgrade the CSS using the system restart method.


    Run the css fast upgrade command to quickly upgrade the CSS.

    During fast CSS upgrade, run the display css fast upgrade state command to check the fast upgrade phase and status.

Updated: 2019-08-21

Document ID: EDOC1000142080

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