Check Optical Signal in Cisco SFP

Optics have to be DOM Compliant.

http://www.cisco.com/en/US/docs/interfaces_modules/transceiver_modules/compatibility/matrix/OL_8031.html
http://www.cisco.com/en/US/docs/interfaces_modules/transceiver_modules/compatibility/matrix/OL_6981.pdf

Some of them will not work.
The command is show interface transceiver. If the transceiver supports DOM, it will show something like this:


show interface transceiver
Transceiver monitoring is disabled for all interfaces.

If device is externally calibrated, only calibrated values are printed.
++ : high alarm, + : high warning, - : low warning, -- : low alarm.
NA or N/A: not applicable, Tx: transmit, Rx: receive.
mA: milliamperes, dBm: decibels (milliwatts).

Optical Optical
Temperature Voltage Current Tx Power Rx Power
Port (Celsius) (Volts) (mA) (dBm) (dBm)
---------- ----------- ------- -------- -------- --------
Te10/1 27.6 ++ 0.00 7.8 ++ -2.0 ++ -2.9 ++
Te10/2 27.4 ++ 0.00 7.8 ++ -2.0 ++ -3.1 ++
Te10/3 24.4 ++ 0.00 0.0 ++ N/A -40.0
Te10/4 23.6 ++ 0.00 0.0 ++ N/A -37.0 ++
Te10/5 25.3 ++ 0.00 0.0 ++ N/A -40.0
Te10/6 25.0 ++ 0.00 0.0 N/A -40.0
Te10/7 24.3 ++ 0.00 0.0 N/A -28.8 ++
Te10/8 26.0 ++ 0.00 0.0 N/A -30.0 ++