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    Manually Switch from Master to Backup Routing Engine

    To manually switch from master to backup Routing Engine, or to force the backup Routing Engine to become master, use the following command:

    user@host> request chassis routing-engine master release

    You can also use the following command:

    user@host> request chassis routing-engine master switch

    For routers with multiple Routing Engines only, you can control which Routing Engine is the master.

    Caution: For routers that have two Routing Engines, both Routing Engines must be running Junos OS Release 4.0 or later. Do not run Junos OS Release 3.4 on one of the Routing Engines and Release 4.0 on the other. Junos OS Release 3.4 does not support Routing Engine redundancy. If you are using this release of the software, only one Routing Engine can be installed in either slot in the router.

    By default, the Routing Engine in slot 0 (RE0) is the master and the Routing Engine in slot 1 (RE1) is the backup. To change the default master Routing Engine, include the routing-engine statement at the [edit chassis redundancy] hierarchy level in the configuration. For more information, see the Junos OS System Basics Configuration Guide.

    When you force the backup Routing Engine to become the master Routing Engine with the request chassis routing-engine master command and then restart the chassis software for any reason, the master reverts to the default setting.

    Note: The configurations on the two Routing Engines do not have to be the same, and they are not automatically synchronized. If you configure both Routing Engines as masters, when the chassis software restarts for any reason, the Routing Engine in slot 0 becomes the master and the Routing Engine in slot 1 becomes the backup.

    We recommend making both configurations the same.

    When both Routing Engines have the same configuration and come up at the same time, the Routing Engine in slot 0 takes precedence over the Routing Engine in slot 1.Table 1 indicates which Routing Engine becomes master based on the configuration of both Routing Engines.

    Table 1: Routing Engine Mastership Election

     

    Slot 0 Configuration

     MasterBackupDisabled
    Slot 1 ConfigurationMaster

    Slot 0: master
    Slot 1: backup

    Slot 0: backup
    Slot 1: master

    Slot 0: disabled
    Slot 1: master

    Backup

    Slot 0: master
    Slot 1: backup

    Slot 0: master
    Slot 1: backup

    Slot 0: disabled
    Slot 1: master

    Disabled

    Slot 0: master
    Slot 1: disabled

    Slot 0: master
    Slot 1: disabled

    Slot 0: disabled
    Slot 1: disabled

    The following command output displays when you attempt to have the backup Routing Engine become master:

    user@M20-host> request chassis routing-engine master acquire
     
    warning: Traffic will be interrupted while the PFE is re-initialized
    
    warning: The other routing engine's file system could be corrupted
    Reset other routing engine and become master ? [yes,no] (no) 
    

    The following command output displays when you switch the mastership from the master Routing Engine to the backup:

    user@m20-host-0> request chassis routing-engine master switch
    warning: Traffic will be interrupted while the PFE is re-initialized
    Toggle mastership between Routing Engines ? [yes,no] (no) yes 
    
    Resolving mastership...
    Complete. The other Routing Engine becomes the master.
    root@m20-host-0>
    

    The following command output displays when you switch the mastership from the backup to the master Routing Engine:

    root@m20-host-0> request chassis routing-engine master switch
    warning: Traffic will be interrupted while the PFE is re-initialized
    Toggle mastership between routing engines ? [yes,no] (no) yes 
    
    Resolving mastership...
    Complete. The local routing engine becomes the master.
    root@m20-host-0>
    

    The command output indicates that traffic will be interrupted during the Routing Engine mastership switch process. The command output confirms whether you really want to continue with the mastership switch process, and indicates when the mastership switch process is complete.

    request chassis routing-engine master <acquire <no-confirm>| release | switch>

    acquire—(Optional) Attempt to become the master Routing Engine.

    no-confirm—(Optional) Do not request confirmation.

    release—(Optional) Request the other Routing Engine to become the master.

    switch—(Optional) Toggle mastership between Routing Engines.

    Published: 2012-08-20