What Is Configuration Rollback? What Is Version Rollback?
Configuration rollback: Some configurations for APs to go online take effect only after the APs restart. If these configurations are incorrect, the APs will fail to go online after the restart. As a result, the APs are out of management and cannot be automatically restored. In this case, network maintenance personnel have to log in to the APs one by one to manually restore the configurations, which leads to long service interruption. As such, APs running V200R008C10 or later support the configuration rollback mechanism to prevent APs from failing to be managed due to incorrect configurations. Based on this mechanism, an AP that fails to go online due to incorrect configurations can rolls back the configuration after a period of time and goes online again.
Version rollback: After an AP is upgraded, it may fail to go online and be out of management, interrupting services for a long time. As such, APs running V200R010 or later support the version rollback mechanism. After the AP version is upgraded, upon an AP exception, the version is rolled back to the source version to prevent the AP out-of-management.
The following figure shows the flowchart for implementing configuration rollback and version rollback.
Configuration Rollback and Version Rollback (Fit AP)
Configuration rollback process
- After a restart, an AP starts a 10-minute timer.
- If the AP does not go online within 10 minutes, it compares the configurations in the current AP configuration files (local_cfg.ini and sysinfo.ini) with the initial configurations or the configurations used by the AP for going online last time. The configurations to be compared include the management VLAN and working mode in the local_cfg.ini file and the IP address in the sysinfo.ini file.
- If the AP has gone online before and has no online STAs, it starts configuration switching. The AP writes the flag for the next configuration startup to the flash memory, and then restarts. The configuration switching sequence is as follows: current configurations -> configurations for the AP to successfully go online last time -> factory configurations.
- After the configuration rollback is complete, the AP writes the current online configurations to the flash memory after going online.
Version rollback process
- After an AP is upgraded successfully, it writes upgrade information, including the version, version boot area, and version rollback flag, to the flash memory.
- After the AP is upgraded successfully and restarts, it starts a 10-minute timer.
- If the AP does not go online within 10 minutes, it performs configuration rollback first. If the AP still cannot go online after the configuration rollback, the AP starts version rollback.
- The AP starts version rollback when the following conditions are met:
- The version rollback flag in the flash memory is enabled.
- The current boot area is the same as that in the flash memory.
- No STA is online on the AP. The AP switches to the standby boot area and restarts.
Then the AP goes online based on the version in the standby boot area.
- After the AP goes online, it clears version information stored in the active boot area of the flash memory.
Configuration Rollback and Version Rollback (Cloud AP)
Configuration rollback process
- After a restart, an AP starts a 2-second timer to periodically check whether it is online on the cloud management controller.
- If the AP is offline for a specified period of time (10 minutes by default, which can be configured using the offline roll-back interval command), certificate-based self-healing is performed. If the interval is set to 0, configuration rollback is not performed.
- If the AP does not go online within 10 minutes after certificate-based self-healing is complete, the AP switches the configurations in the following sequence: configurations for the AP to successfully go online last time -> current configurations.
- After the configuration rollback is complete, the AP writes the current online configurations to the flash memory when it is online for more than 10 minutes.
Version rollback process
Scenario 1: The AP is upgraded successfully.
- After an AP is upgraded successfully, it writes upgrade information, including the version, version boot area, and version rollback flag, to the flash memory. At the same time, the AP starts a 30-minute timer.
- If the AP does not go online within 10 minutes after the upgrade, the AP performs configuration rollback. If the AP still cannot go online after the configuration rollback, the AP starts version rollback.
- With the offline self-healing function enabled, the AP starts version rollback when the following conditions are met:
- The version rollback flag in the flash memory is enabled.
- The current boot area is the same as that in the flash memory.
- No STA is online on the AP.
The AP switches to the standby boot area and restarts. Then the AP goes online based on the version in the standby boot area.
- After the AP goes online, it clears version information stored in the active boot area of the flash memory.
Scenario 2: The AP upgrade is not taken into account.
- The AP starts a 2-second timer to periodically check whether it is online on the cloud management controller.
- If the offline self-healing function is disabled or the AP has never gone online, version rollback is not performed.
- After a high-risk configuration is performed, if an AP goes offline within 10 minutes and does not go online within 30 minutes, the AP initiates the restart process. Specifically, the AP checks whether there are online STAs. If not, the AP restarts; if so, the AP waits for the next check but does not restart.
Currently, high-risk configurations include:
- Configure a static IP address for a VLANIF interface on the cloud management controller.
- Enable the DHCP client function on a VLANIF interface of the cloud management controller.
- Configure static routes on the cloud management controller.
- If an AP does not go online for more than 24 hours (24 hours by default, which can be configured through the offline self-healing-reset timeout command), the AP initiates the restart process. That is, the AP checks whether there are online users. Specifically, the AP checks whether there are online STAs. If not, the AP restarts; if so, the AP waits for the next check but does not restart.