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I have cisco catalyst 3750x 24 port switch series switch, and the switch has C3KX-NM-10G module.

Problem :

I have connected fibre optic in SFP+ transceiver on G2/TE1 (Uplink).  After 7 to 8 hours, the SFP+ transceiver stops working (Lights off state). There is no data transmission.  If I removed the SFP+ transceiver and reinserted, then the connection coming back to normal (Lights Blink). The data transmission starts again. This is happening daily.

While Checking the logs I found this error.

Tx power low alarm and Rx power low alarm (Is this an SFP Transceiver issue)

    ASW-G-L09-001#show logging
Log Buffer (8192 bytes):
D_VIOLATION: Te1/1/1: Tx power low alarm; Operating value: -40.0 dBm, Threshold value: -11.3 dBm.
019031: May 18 12:27:34.016: %PLATFORM_ENV-1-FRU_PS_ACCESS: FRU Power Supply is not responding
019032: May 18 12:32:21.988: %SFF8472-5-THRESHOLD_VIOLATION: Te1/1/1: Tx power low alarm; Operating value: -40.0 dBm, Threshold value: -11.3 dBm.
019071: May 18 14:48:36.536: %PLATFORM_ENV-1-FRU_PS_ACCESS: FRU Power Supply is not responding
019072: May 18 14:52:25.536: %SFF8472-5-THRESHOLD_VIOLATION: Te1/1/1: Rx power low alarm; Operating value: -40.0 dBm, Threshold value: -13.9 dBm.
019073: May 18 14:52:25.536: %SFF8472-5-THRESHOLD_VIOLATION: Te1/1/1: Tx power low alarm; Operating value: -40.0 dBm, Threshold value: -11.3 dBm.
019074: May 18 14:52:57.740: %LINK-3-UPDOWN: Interface TenGigabitEthernet1/1/1, changed state to up
019075: May 18 14:52:59.770: %LINEPROTO-5-UPDOWN: Line protocol on Interface TenGigabitEthernet1/1/1, changed state to up
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    Start by looking at your logs. What do they tell you? Also, what does the device on the other end report?
    – Teun Vink ♦
    Nov 30, 2020 at 15:40
  • 1
    I've seen fiber channel interfaces do this when the optic overheats. (bad airflow design)
    – Ricky
    Nov 30, 2020 at 16:46
  • You should monitor the SFP+ modules' diagnostics (DOM) data for overheating, receive power margin, or transmit power fluctuation. Compare values from just linked, after 1-2 hours and when failed.
    – Zac67 ♦
    Nov 30, 2020 at 18:03
  • Did any answer help you? if so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could post and accept your own answer.
    – Ron Maupin ♦
    Dec 31, 2020 at 4:28

2 Answers 2

Reset to default
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As @teunvink says, check your logs. You can also check the SFP+ with this command:

show interface te x/y/z transceiver detail

and

show interface te x/y/z transceiver properties
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2

Looks like a hardware issue. The transmitter fails:

D_VIOLATION: Te1/1/1: Tx power low alarm; Operating value: -40.0 dBm, Threshold value: -11.3 dBm.

Possibly due to PSU problems:

019031: Dec 20 12:27:34.016: %PLATFORM_ENV-1-FRU_PS_ACCESS: FRU Power Supply is not responding

I'd try another SFP+ module and if that doesn't help swap the PSU.

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