It works fine, and is supported by the spec (as opposed to "out of spec, but happens to work"). If you have a port that will let you see both the thresholds and actual values, you can confirm this. For example:LR over short distance are not a good idea. Pretty sure it won't work.
Code:
Optical High Alarm High Warn Low Warn Low Alarm
Transmit Power Threshold Threshold Threshold Threshold
Port (dBm) (dBm) (dBm) (dBm) (dBm)
--------- ----------------- ---------- --------- --------- ---------
Gi1/0/2 -5.6 0.0 -0.5 -10.0 -11.0
Optical High Alarm High Warn Low Warn Low Alarm
Receive Power Threshold Threshold Threshold Threshold
Port (dBm) (dBm) (dBm) (dBm) (dBm)
------- ----------------- ---------- --------- --------- ---------
Gi1/0/2 -13.0 1.0 0.0 -28.2 -30.0
With -ER (40km) and -ZR (80km) parts you will need attenuators.
This is -ER:
Code:
Optical High Alarm High Warn Low Warn Low Alarm
Transmit Power Threshold Threshold Threshold Threshold
Port (dBm) (dBm) (dBm) (dBm) (dBm)
--------- ----------------- ---------- --------- --------- ---------
Te4/0/1 2.2 8.0 4.0 -4.7 -8.7
Optical High Alarm High Warn Low Warn Low Alarm
Receive Power Threshold Threshold Threshold Threshold
Port (dBm) (dBm) (dBm) (dBm) (dBm)
------- ----------------- ---------- --------- --------- ---------
Te4/0/1 -7.9 3.0 -1.0 -15.8 -19.8
Code:
Optical High Alarm High Warn Low Warn Low Alarm
Transmit Power Threshold Threshold Threshold Threshold
Port (dBm) (dBm) (dBm) (dBm) (dBm)
--------- ----------------- ---------- --------- --------- ---------
Te1/1 2.2 5.9 2.9 -1.0 -5.0
Optical High Alarm High Warn Low Warn Low Alarm
Receive Power Threshold Threshold Threshold Threshold
Port (dBm) (dBm) (dBm) (dBm) (dBm)
------- ----------------- ---------- --------- --------- ---------
Te1/1 -18.7 -3.0 -7.0 -27.2 -31.5
There are 15km and 20km -LR parts available, as well as -ZR+ (100km, 120km) parts. The extended range -LR parts may be able to be overloaded with short cables. The extended range -ZR+ parts will definitely overload, just like the -ER and -ZR parts.