11-High Availability Configuration Guide

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02-Active and Standby Switchover Configuration
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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;

1.      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

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

Manually performing an active and standby switchover

Optional

 

Ignoring version check of the standby MPU

When the standby MPU starts up, the system checks the versions of the active MPU and standby MPU. If the versions of the active MPU and standby MPU are not consistent, the standby MPU cannot be started.

To disable the system from checking the version of the standby MPU:

 

Step

Command

Remarks

1.     Enter system view.

system-view

N/A

2.     Ignore version check of the standby MPU.

ha slave-ignore-version-check

Enabled by default.

 

Restarting the standby MPU

When the standby MPU fails, or is to be upgraded, you can restart the standby MPU to validate the newest version or configuration. However, you need to check the consistency of the versions of the active MPU and standby MPU. If they are not consistent, configure to ignore version check of the standby MPU.

To restart the standby MPU:

 

Step

Command

1.     Enter system view.

system-view

2.     Manually restart the standby MPU.

slave restart

 

 

NOTE:

When the standby MPU is restarted, the active MPU performs initial synchronization on the standby MPU. During this process, the system does not respond to your input. When the initial synchronization is completed, you can execute all the configuration commands on the active MPU and the active MPU and standby MPU keep a real-time synchronization process, meaning your configuration on the active MPU will be copied to the standby MPU to ensure the consistency of the current configuration of the active MPU and standby MPU.

 

Manually performing an active and standby switchover

To upgrade the active MPU, restart the active MPU. To avoid service interruption in this case, perform a manual active and standby switchover to enable the standby MPU to take over the active MPU.

To manually perform an active and standby switchover:

 

Step

Command

Remarks

1.     Enter system view.

system-view

N/A

2.     Enable manual active and standby switchover.

slave switchover { disable | enable }

Optional

Enabled by default

3.     Manually perform active and standby switchover.

slave switchover

N/A

 

CAUTION

CAUTION:

The original active MPU is restarted when an active MPU and standby MPU switchover is performed. Therefore, ensure the consistency of the software version of the active MPU and standby MPU before performing an active and standby switchover. If their software version is not consistent, you need to configure to ignore version check of the standby MPU first.

 

Displaying and maintaining active and standby switchover

 

Task

Command

Remarks

Display the switchover state of the specified MPU.

display switchover state [ slot slot-number ] [ | { begin | exclude | include } regular-expression ]

Available in any view