Rx power low warning in cisco 2960Cx

[shekhar belsare]

I am getting below error in cisco 2960cx switch and switch is showing not online.

[shekhar belsare]

Log Buffer (4096 bytes):
warning; Operating value: -21.1 dBm, Threshold value: -19.0 dBm.
Oct 28 04:04:27.573: %SFF8472-5-THRESHOLD_VIOLATION: Gi0/11: Rx power low warning; Operating value: -21.1 dBm, Threshold value: -19.0 dBm.
Oct 28 04:14:28.522: %SFF8472-5-THRESHOLD_VIOLATION: Gi0/11: Rx power low warning; Operating value: -21.1 dBm, Threshold value: -19.0 dBm.

[M02@rt37]

I confirm @shekhar belsare,

the received optical power on interface GigabitEthernet 0/11 is lower than the expected threshold (-19.0 dBm). This might be due to issues with the SFP module, the fiber cable. It's important to address this issue to ensure proper network connectivity. You may want to start by checking the SFP module, the fiber cable, and the cleanliness of the connectors....potential replacement of the SFP module or cable may be required.

[pieterh]

did it work before ?
if not (new installation) then check that the SFP matches the fiber patch cable AND the site-to-site fibre cable (all SM or all MM)
you might be pushing light from a MM SFP (50um) through a SM cable (9um) so much light is lost on the junction between the two cables

if it did work before
- replace SFP's (they get old within time)
- check the fiber cable for damage (if possible have the site-site fiber measured
- check bending radius of the the fiber patch cables  (or replace them)

[shekhar belsare]

Hi,

Thanks for the help. we have SM SFP but MM fiber patch cords for point to point to switch connectivity.

Please guide

[M02@rt37]

Hello @shekhar belsare,

Single-Mode SFP modules should be used with Single-Mode fiber, and Multi-Mode SFP modules should be used with Multi-Mode fiber. Using the wrong combination can lead to signal loss and poor performance.

As I said before: the received optical power on interface GigabitEthernet 0/11 is lower than the expected threshold (-19.0 dBm). This might be due to issues with the SFP module, the fiber cable. It's important to address this issue to ensure proper network connectivity. You may want to start by checking the SFP module, the fiber cable, and the cleanliness of the connectors....potential replacement of the SFP module or cable may be required.

[shekhar belsare]

As i checked, we have laid 12 core OFC and Single mode SFP, but the patch cords are multilode , so replacing patch cords will help to improve signal strength.

[M02@rt37 · Accepted solution]

Hello @shekhar belsare,

The "Rx power low warning" message typically indicate an issue with the received optical power on one of the switch's SFP modules or interfaces. This warning is generated when the received optical power falls below an acceptable threshold.