H3C Technologies H3C SR8800 - Manual (Page 14)

5
Configuring active and standby switchover
Introduction to active and standby switchover
If a router has two main processing units (MPUs), the MPU that forwards and processes packets is called
the active MPU, and the MPU that is in the standby state is called the standby MPU. The system uses the
MPU with a smaller slot number as the active MPU, and the other MPU as the standby MPU. The standby
MPU keeps its configuration the same as the active MPU through the synchronization function. When the
active MPU fails, the standby MPU becomes the active MPU to process services to ensure the normal
operation of the router. This switchover process is called an active and standby switchover.
Active and standby switchover functions in the following two ways:
• Automatic active and standby switchover. If the active MPU fails or is plugged out, the system
automatically performs an active and standby switchover to enable the standby MPU to function as
the active MPU.
• Manual active and standby switchover, which is performed at the command line interface (CLI). For
example, when you upgrade a router, you can upgrade the standby MPU first, and then perform an
active and standby switchover to upgrade the active MPU, thus to upgrade the entire router. This
upgrade mode greatly reduces the interruption time of services.
When you upgrade the router by performing an active and standby switchover, the current software
version must be gracefully upgraded (in other words, the differences between the new version and the
current version are relatively small.); otherwise, the standby MPU may not be started. To upgrade a router
by performing an active and standby switchover:
1. Download the newest software version to the active MPU and standby MPU respectively;
2. Specify the boot file to be used at the next startup of the active MPU and standby MPU as the
newest software version respectively;
3. Ignore version check for the standby MPU;
4. Manually restart the standby MPU to upgrade the standby MPU;
5. Manually perform an active and standby switchover. Then the standby MPU becomes the active
MPU to take over the original active MPU, and the original active MPU automatically restarts by
using the new version to upgrade the router.
CAUTION:
You cannot execute any command on the standby MPU, and you need to perform configurations at the CLI
of the active MPU, which then synchronizes the configurations to the standby MPU.
Active and standby switchover configuration task
list
Task Remarks
Ignoring version check of the standby MPU Optional
Restarting the standby MPU Optional