Description

How to remotely power cycle a backup RE that is in "Present" state on a M320 or T Series router?

Symptoms

Sometimes, backup RE may be stuck in boot mode or it lost communication with primary RE. If accessing the router remotely, you may want to power cycle for the backup RE to try to bring it back. Normally a local support engineer could reinsert it or press the reset button. If the router is a M320, M40e. or T Series router, you can try to power cycle the backup RE without local support.

When current backup RE is in  Present state, it can not be accessed from primary RE: 

lab@Johnny-re0> show chassis routing-engine
Routing Engine status:
  Slot 0:
    Current state                  Master
    Election priority              Master (default)
    Temperature                 27 degrees C / 80 degrees F
    CPU temperature             32 degrees C / 89 degrees F
    DRAM                      2048 MB
    Memory utilization          30 percent
    CPU utilization:
      User                       2 percent
      Background                 0 percent
      Kernel                     2 percent
      Interrupt                  1 percent
      Idle                      96 percent
    Model                          RE-4.0
    Serial ID                      P11123904115
    Start time                     2009-05-25 14:11:23 UTC
    Uptime                         3 days, 3 hours, 32 minutes, 53 seconds
    Last reboot reason             Router rebooted after a normal shutdown.
    Load averages:                 1 minute   5 minute  15 minute
                                       0.09       0.04       0.01
Routing Engine status:
  Slot 1:
    Current state                  Present

lab@Johnny-re0>

Solution

For M320 or T Series, the Control Board (CB) would supply power to the Routing Engine (RE) (MCS on M40e). If the backup RE is stuck in Present state, you can offline/online the CB to simulate a power cycle of the backup RE. This could potentially resolve the problem with the backup RE and restore it to a working state. 
lab@Johnny-re0> show chassis routing-engine 
Routing Engine status:
  Slot 0:
    Current state                  Master
    Election priority              Master (default)
    Temperature                 27 degrees C / 80 degrees F
    CPU temperature             32 degrees C / 89 degrees F
    DRAM                      2048 MB
    Memory utilization          30 percent
    CPU utilization:
      User                       2 percent
      Background                 0 percent
      Kernel                     2 percent
      Interrupt                  1 percent
      Idle                      96 percent
    Model                          RE-4.0
    Serial ID                      P11123904115
    Start time                     2009-05-25 14:11:23 UTC
    Uptime                         3 days, 3 hours, 33 minutes, 29 seconds
    Last reboot reason             Router rebooted after a normal shutdown.
    Load averages:                 1 minute   5 minute  15 minute
                                       0.05       0.03       0.00
Routing Engine status:
  Slot 1:
    Current state                  Present

lab@Johnny-re0> request chassis cb slot 1 offline 
Offline initiated, use "show chassis environment cb" to verify

lab@Johnny-re0> show chassis environment cb 1    
CB 1 status:
  State                      Offline
  Power                      Disabled             

lab@Johnny-re0> request chassis cb slot 1 online     
Online initiated, use "show chassis environment cb" to verify

lab@Johnny-re0> show chassis environment cb 1       
CB 1 status:
  State                      Offline
  Power 1                    
    1.8 V bias                1802 mV
    2.5 V TOP                 2504 mV
    3.3 V                     3308 mV
    3.3 V bias *              3291 mV
    4.6 V bias MidPlane       4725 mV
    5.0 V bias                5023 mV
    9.0 V                     7208 mV
    12.0 V RE                11956 mV
  Bus Revision               40
  FPGA Revision              8

lab@Johnny-re0>
After 5 minutes, the backup RE is functional again. 
lab@Johnny-re0> show chassis routing-engine    
Routing Engine status:
  Slot 0:
    Current state                  Master
    Election priority              Master (default)
    Temperature                 27 degrees C / 80 degrees F
    CPU temperature             32 degrees C / 89 degrees F
    DRAM                      2048 MB
    Memory utilization          30 percent
    CPU utilization:
      User                       2 percent
      Background                 0 percent
      Kernel                     2 percent
      Interrupt                  0 percent
      Idle                      96 percent
    Model                          RE-4.0
    Serial ID                      P11123904115
    Start time                     2009-05-25 14:11:23 UTC
    Uptime                         3 days, 3 hours, 37 minutes, 38 seconds
    Last reboot reason             Router rebooted after a normal shutdown.
    Load averages:                 1 minute   5 minute  15 minute
                                       0.14       0.07       0.02
Routing Engine status:
  Slot 1:
    Current state                  Backup
    Election priority              Backup (default)
    Temperature                 35 degrees C / 95 degrees F
    CPU temperature             31 degrees C / 87 degrees F
    DRAM                      1280 MB
    Memory utilization          16 percent
    CPU utilization:
      User                      10 percent
      Background                 0 percent
      Kernel                     5 percent
      Interrupt                  0 percent
      Idle                      85 percent
    Model                          RE-3.0
    Serial ID                      P12040700841
    Start time                     2009-05-28 17:46:25 UTC
    Uptime                         2 minutes, 39 seconds
    Last reboot reason             Router rebooted after a normal shutdown.

lab@Johnny-re0>
For M40e, use mcs instead of cb : 
request chassis mcs slot 0|1 offline
request chassis mcs slot 0|1 online.
note: If the backup RE is working correctly, you can not disable corresponding CB as shows by following output: 
lab@Johnny-re0> show chassis routing-engine 
Routing Engine status:
  Slot 0:
    Current state                  Master
    Election priority              Master (default)
    Temperature                 27 degrees C / 80 degrees F
    CPU temperature             32 degrees C / 89 degrees F
    DRAM                      2048 MB
    Memory utilization          30 percent
    CPU utilization:
      User                       2 percent
      Background                 0 percent
      Kernel                     2 percent
      Interrupt                  0 percent
      Idle                      95 percent
    Model                          RE-4.0
    Serial ID                      P11123904115
    Start time                     2009-05-25 14:11:23 UTC
    Uptime                         3 days, 3 hours, 27 minutes, 28 seconds
    Last reboot reason             Router rebooted after a normal shutdown.
    Load averages:                 1 minute   5 minute  15 minute
                                       0.07       0.06       0.03
Routing Engine status:
  Slot 1:
    Current state                  Backup
    Election priority              Backup (default)
    Temperature                 29 degrees C / 84 degrees F
    CPU temperature             25 degrees C / 77 degrees F
    DRAM                      1280 MB
    Memory utilization          17 percent
    CPU utilization:
      User                       0 percent
      Background                 0 percent
      Kernel                     0 percent
      Interrupt                  0 percent
      Idle                     100 percent
    Model                          RE-3.0
    Serial ID                      P12040700841
    Start time                     2009-04-24 12:07:57 UTC
    Uptime                         34 days, 5 hours, 30 minutes, 41 seconds
    Last reboot reason             Router rebooted after a normal shutdown.


lab@Johnny-re0> request chassis cb slot 1 offline    
Backup CB 1 cannot be set offline, backup RE is online

lab@Johnny-re0>