17Active and standby switchover configuration• The switch operates in IRF or standalone (the default) mode. For more information about the IRF mode,see IRF in the IRF Configuration Guide.• When the device works in standalone mode, you can use the features and functions in this manual torestart the SMB to perform an active and standby switchover, to implement redundant backup betweenthe AMB and the SMB. When the device works in IRF mode, you can only use the displayswitchover state command to view the backup state of the main boards, and other functions andcommands do not take effect.Introduction to active and standby switchoverIf a device has two main boards, the main board that forwards and processes packets is calledthe AMB, and the main board that is in the standby state is called the SMB. The system uses themain board with a smaller slot number as the AMB, and the other main board as the SMB. TheSMB keeps its configuration the same as the AMB through the synchronization function. Whenthe AMB fails, the SMB becomes the AMB to process services to ensure the normal operation ofthe device. This switchover process is called an active and standby switchover.Active and standby switchover functions in the following ways:• Automatic active and standby switchover. If the AMB fails or is disconnected, the systemautomatically performs an active and standby switchover to enable the SMB to function asthe AMB.• Manual active and standby switchover, which is an active and standby switchoverperformed at the command line interface. For example, when you upgrade a device, youcan upgrade the SMB first, and then perform an active and standby switchover to upgradethe AMB, to upgrade the entire device. This greatly reduces the interruption time of services.When you upgrade the device by performing an active and standby switchover, the currentsoftware version must be gracefully upgraded (that is, the differences between the new versionand the current version are relatively small.); otherwise, the SMB may not be started. To upgradea device by performing an active and standby switchover:1. Download the newest software version to the AMB and SMB.2. Specify the boot file to be used at the next startup of the AMB and SMB as the newestsoftware version.3. Ignore version check for the SMB.4. Manually restart the SMB to upgrade the SMB.5. Manually perform an active and standby switchover. Then the SMB becomes the AMB,taking over from the original AMB, and the original AMB automatically restarts, using thenew version to upgrade the device.
