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    Configuring Graceful Routing Engine Switchover

    This section contains the following topics:

    Enabling Graceful Routing Engine Switchover

    By default, graceful Routing Engine switchover (GRES) is disabled. To configure GRES, include the graceful-switchover statement at the [edit chassis redundancy] hierarchy level.

    When you enable GRES, the command-line interface (CLI) indicates which Routing Engine you are using. For example:

    {master} [edit]user@host#

    To disable GRES, delete the graceful-switchover statement from the [edit chassis redundancy] hierarchy level.

    Configuring Graceful Routing Engine Switchover with Graceful Restart

    When using GRES with Graceful Restart, if adjacencies between the Routing Engine and the neighboring peer 'helper' routers time out, graceful restart protocol extensions are unable to notify the peer 'helper' routers about the impending restart. Graceful restart can then stop and cause interruptions in traffic.

    To ensure that these adjacencies are kept, change the hold-time for IS-IS protocols from the default of 27 seconds to a value higher than 40 seconds.

    Synchronizing the Routing Engine Configuration

    Note: A newly inserted backup Routing Engine automatically synchronizes its configuration with the master Routing Engine configuration.

    When you configure GRES, you can bring the backup Routing Engine online after the master Routing Engine is already running. There is no requirement to start the two Routing Engines simultaneously.

    Only when you enable the graceful Routing Engine switchover, you can copy the running Junos OS version of the master Routing Engine to the backup Routing Engine.

    Note: If the system is in ISSU state, you cannot copy the running Junos OS version of the master Router Engine.

    Starting in Junos OS release 14.1, you can enable automatic synchronization of the master Routing Engine configuration with the backup Routing Engine by including the events CHASSISD_SNMP_TRAP7 statement at the [edit event-options policy policy-name] hierarchy level.

    CHASSISD_SNMP_TRAP7 is a system event logging message that the chassis process (chassisd) generates a Simple Network Management Protocol (SNMP) trap with the seven indicated argument-value pairs. An example of an event script to trigger automatic synchronization of master to the backup Routing Engine is as follows:

    [edit event-options]
    policy UPGRADE-BACKUPRE {
    events CHASSISD_SNMP_TRAP7;
    attributes-match {
    CHASSISD_SNMP_TRAP7.value5 matches "Routing Engine";
    CHASSISD_SNMP_TRAP7.trap matches "Fru Online";
    CHASSISD_SNMP_TRAP7.argument5 matches jnxFruName;
    }
    then {
    event-script auto-image-upgrade.slax {
    arguments {
    trap "{$$.trap}";
    value5 "{$$.value5}";
    argument5 "{$$.argument5}";
    }
    }
    }
    }
    event-script {
    file auto-image-upgrade.slax;
    }

    After receiving this event, the event policy on the master Router Engine is triggered and the image available in the /var/sw/pkg path is pushed to the backup Router Engine upgrade. During script execution, the image is copied to the backup Routing Engine's /var/sw/pkg path.

    Note: If the image is not available in the /var/sw/pkg path, the script is terminated with an appropriate syslog message.

    If the Routing Engine is running at the Junos OS Release 13.2 or later, the Junos automation scripts is synchronized automatically.

    After the master Router Engine is rebooted, the event script available at the /usr/libexec/scripts/event/auto-image-upgrade.slax must be copied to the /var/db/scripts/event path.

    Verifying Graceful Routing Engine Switchover Operation

    To verify whether GRES is enabled on the backup Routing Engine, issue the show system switchover command. When the output of the command indicates that the Graceful switchover field is set to On, GRES is operational. The status of the kernel database and configuration database synchronization between Routing Engines is also provided. For example:

    Graceful switchover: On
    Configuration database: Ready
    Kernel database: Ready
    Peer state: Steady state

    Note: You must issue the show system switchover command on the backup Routing Engine. This command is not supported on the master Routing Engine.

    For more information about the show system switchover command, see the CLI Explorer.

     

    Related Documentation

     

    Release History Table

    Release
    Description
    Starting in Junos OS release 14.1, you can enable automatic synchronization of the master Routing Engine configuration with the backup Routing Engine by including the events CHASSISD_SNMP_TRAP7 statement at the [edit event-options policy policy-name] hierarchy level.

    Modified: 2016-06-06