First, a C25 DWDM SFP+ optical module with a transmission distance of 80km is installed on the SFP+ port of the Cisco Catalyst 4948E. Next, the LC-LC single-mode fiber jumper is used to connect the transmit port of the SFP+ optical module to the receive port of the CH25 port of the dense wavelength division multiplexer/demultiplexer. Then, the LC-SC single-mode simplex fiber jumper is used to connect the transmit port in the COM port of the dense wavelength division multiplexing & demultiplexer to the optical power meter.
It should be noted that all optical interfaces need to be cleaned before connection to ensure the accuracy of the test results.
Press the λ button to select a wavelength of 1550 nm, and then you can see that the optical power value of the signal from the C25 DWDM SFP+ optical module is 2.68 dB. As shown in the figure above, when the optical signal passes through LC-LC single-mode simplex fiber jumper (loss 1), CH25 port, LC-SC single-mode simplex fiber jumper (loss 2) and COM port (loss 3) At the time, light loss occurs.
A simple formula can be obtained:
Input Power - Insertion Loss (CH25) - Loss 1 (LC-LC) - Loss 2 (LC-SC) - Loss 3 (COM Port) = 2.68 dB (REF Value)
If you want to get the insertion loss value of the CH25 port, the formula will be:
Insertion Loss (CH25) = Input Power - Loss 1 (LC-LC) - Loss 2 (LC-SC) - Loss 3 (COM Port) - 2.68dB (REF Value)
You can set 2.68dB as a reference value. If the optical power value of the CH25 SFP+ can be tested after going through these three loss points, then the difference will be the insertion loss of the CH25CH port.
Since COM ports can be considered fiber adapters, we will use adapters to connect LC-SC single-mode simplex fiber jumpers and LC-LC single-mode simplex fiber jumpers. Then, they are connected to an optical power meter as shown in the figure above. At this time, a difference of 3.58dB can be obtained. This value is the insertion loss of the CH25 port on this 40CH dense wavelength division multiplexing & demultiplexers.
