When connecting 2 nexus 93108 with 40Gigabit WSP-Q40GLR4L over 15 meter with single mode cable (with fiber optics patch panel).
There is on one side on the first lane a weak receive power on the optical signal.
switch-002# sh int eth1/52 trans det | i Rx
Rx Power -7.49 dBm 3.29 dBm -17.95 dBm 2.29 dBm -13.76 dBm
Rx Power 1.03 dBm 3.29 dBm -17.95 dBm 2.29 dBm -13.76 dBm
Rx Power 0.75 dBm 3.29 dBm -17.95 dBm 2.29 dBm -13.76 dBm
Rx Power 1.00 dBm 3.29 dBm -17.95 dBm 2.29 dBm -13.76 dBm
The receive power on the first lane ist constantly decreasing from day to day.
What can be the reason that the signal on one lane is fading ?
nothing in the logs.
The QSFP was already replaced after the the optical receive power felt below thresholds and the links gone down. After replacement the problem occurs in the opposite direction. With the same effect, each day the receive power is decreasing very slow on the first lane.
over 15 meter with single mode cable
You are using single-mode optics and cables for just over 15 metes?
This may be an issue as single-mode optics and cables are designed for long distances.
Try testing with multimode optics and cables?