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Determining GRES Readiness in a Virtual Chassis Configuration

Depending on the configuration, a variable amount of time is required before a router or switch is ready to perform a graceful Routing Engine switchover (GRES). Attempting a GRES operation before the device is ready can cause system errors and unexpected behavior.

To determine whether the member routers or switches in a Virtual Chassis configuration are ready for a GRES operation from a database synchronization perspective, you can issue the request virtual-chassis routing-engine master switch check command from the Virtual Chassis master router or switch (VC-Mm) before you initiate the GRES operation. Using the request virtual-chassis routing-engine master switch check command before you initiate the GRES operation ensures that the subscriber management and kernel databases on both member routers or switches are synchronized and ready for the GRES operation.

To determine whether the member routers or switches are ready for GRES from a database synchronization perspective:

  1. Issue the request virtual-chassis routing-engine master switch check command from the Virtual Chassis master router or switch (VC-Mm).
    {master:member0-re0}

    The request virtual-chassis routing-engine master switch check command checks various system and database components on the member routers or switches to determine whether they are ready for GRES, but does not initiate the global GRES operation itself. The readiness check includes ensuring that a system timer, which expires after 300 seconds, has completed before the global GRES operation can begin.

  2. Review the results of the request virtual-chassis routing-engine master switch check command to determine whether the member routers or switches are ready for a GRES operation from a database synchronization perspective.

    • If the member routers or switches are ready for GRES, the request virtual-chassis routing-engine master switch check command returns the command prompt and displays no output.
      {master:member0-re0}
      {master:member0-re0}
    • If the member routers or switches are not ready for GRES, the request virtual-chassis routing-engine master switch check command displays information about the readiness of the system. For example:
      {master:member0-re0}
      error: chassisd Not ready for mastership switch, try after 217 secs.
mastership switch request NOT honored, backup not ready

      The specific command output differs depending on the GRES readiness state of the member routers or switches.

 

Related Documentation

 

Published: 2013-11-12

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