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Syslog message: Alarm set: N+1 Power redundancy missing

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Article ID: KB28431 KB Last Updated: 25 Nov 2013Version: 1.0
Summary:
The alarm indicates the corresponding zone in the chassis (in an MX2020 or MX2010) does not have sufficient power remaining to guarantee Power Supply Module (PSM) N+1 redundancy.   
Symptoms:
SYMPTOMS:
One of several error messages is displayed:
  • In case of MX2020 Upper zone:  N+1 Power redundancy missing in Upper zone
  • In case of MX2020 Lower zone:  N+1 Power redundancy missing in Lower zone
  • In case of MX2010:  N+1 Power redundancy missing

EXAMPLE:
  1. An MX2020 chassis upper zone has five PSMs and the lower zone has four PSMs.
    user@router> show chassis power
    -snip-
    System:
    Upper Zone:
    Capacity: 10500 W (maximum 10500 W)
    Allocated power: 4530 W (5970 W remaining)
    Actual usage: 805.19 W
    Lower Zone:
    Capacity: 8400 W (maximum 8400 W)
    Allocated power: 4530 W (3870 W remaining)
    Actual usage: 828.00 W
    Total system capacity: 18900 W (maximum 18900 W)
    Total remaining power: 9840 W


    Notes:
    * 2100W x 5 PSM provides 10500W for upper zone.
    * 2100W x 4 PSM provides 8400W for lower zone.
    * Lower zone's remaining power is 3870W which is higher than PSM power rate 2100W.
  2. Remove one PSM from the lower zone.  This reduces the remaining power of lower zone to 1770W.
    user@router> show chassis power
    -snip-
    System:
    Upper Zone:
    Capacity: 10500 W (maximum 10500 W)
    Allocated power: 4530 W (5970 W remaining)
    Actual usage: 948.06 W
    Lower Zone:
    Capacity: 6300 W (maximum 6300 W)
    Allocated power: 4530 W (1770 W remaining)
    Actual usage: 1099.69 W
    Total system capacity: 16800 W (maximum 16800 W)
    Total remaining power: 7740 W
  3. This will trigger the alarm to appear.
    user@router> show chassis alarms
    1 alarms currently active
    Alarm time Class Description
    2013-11-20 22:39:18 PDT Minor N+1 Power redundancy missing in Lower zone


Solution:
This informational log indicates that the chassis needs more power to guarantee PSM redundancy.  Please calculate the power requirements using the related links below and add more PSM if it is needed.

Related Links

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