05-21-2008 07:03 AM
I have noticed the majority of the SFPs in our 4100 switches have tx power levels of between 300-400 uWatts. However there are a handful that are around the 260 uWatts level and these ports seem more likely to have enc_out errors.
Is this purely coincidental or does a low tx power (or rx power) level indicate a faulty cable, gbic or hba?
11-07-2008 09:24 AM
I think remember that the optical loss budget is -20db. If the typical Tx/Rx power is 300 uW, it would seem, that an input power of 3 uW would be adequate. A varation of a db or two would be inconsequential on the RX side. On the Tx side however, I don't know if it could indicate a problem.