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Cisco Bug: CSCum48844 - Cat4k - Brief Packet Loss/Uneven PoE Distro After Double PS Failover

Last Modified

Jun 28, 2020

Products (1)

  • Cisco Catalyst 4000 Series Switches

Known Affected Releases


Description (partial)

On a Catalyst 4500, a brief moment of packet loss may be experienced by connected PoE devices, after failing over between power supplies twice (e.g failover from PS1 to PS2, then a few mins later failover from PS2 to 1). The following logs may be printed:
 %C4K_ETHPOE-4-SUPPLYFAULT: Module 3 POE controller has been shutdown because of excessive power usage.
%C4K_ETHPOE-4-SUPPLYFAULT: Module 1 POE controller has been shutdown because of excessive power usage.

Prior to the 2nd failover that leads to the packet loss,  the inline power may not be evenly distributed across power supplies, as indicated in "show power"


                             Output Power To Chassis            Input Power
                    =======================================  ==================
Power Measurement   System Power (12V)  Inline Power (-50V)
(in Watts)                (+/- 12W)        (+/- 50W)              (+/- 5%)
------------------  ------------------  -------------------  ------------------
PS1                        349                  695                 1290
PS2                          0                    0                    0
------------------  ------------------  -------------------  ------------------
Total                      349                  695                 1290

This issue has been seen with a small range of PWR-C45-6000ACV power supplies. To trigger the issue, the following steps were performed:

1.Turn on both power supplies
2.Turn off power supply 1
3.Turn on power supply 1. "show power: output shows inline power is not distributed evenly across power supplies, even though both power supplies are 'good'. (there should be no impact yet)
4. Failing over from power supply 1 to power supply 2 will lead to a brief period of packet loss and the above mentioned log messages.

Related Community Discussions

WS-4748 ports not granting POE power
4510 switch with 4 WS-4748-UPOE cards and now 2 of those cards are not granting POE to Cisco 8851 phones. Plenty of power and these cards were granting power and have some phones on them. The issues just seems to be on cards 1 &amp; 4. Cards 2 &amp; 3 will grant power.   sw1#sho power det Power Fan Inline Supply Model No Type Status Sensor Status ------ ---------------- --------- ----------- ------- ------- PS1 PWR-C45-4200ACV AC 4200W good good good PS1-1 220V good PS1-2 220V good PS2 PWR-C45-4200ACV AC ...
Latest activity: Oct 11, 2017
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