CWDM/DWDM Mux Ports: What You Need to Know

Updated on Nov 4, 2021

Fiber Mux Demux is a main C/DWDM device to build a higher-capacity C/DWDM network. Both CWDM and DWDM Mux Demux have several types of ports that are quite common to use for increasing the existing fiber optic network capacity without adding any fibers. However, how much do you know about the mux ports on the C/DWDM Mux Demux, such as line port, monitor port, expansion port, etc? Are you familiar with the applications of these different C/DWDM Mux Ports? Get the details about the mux port explanation in the following text for better usage of C/DWDM Mux Demux.

Must-Have Ports on CWDM/DWDM Mux Demux

As we know, the basic function of the C/DWDM Mux Demux is combining data rates of different wavelengths over the same fiber cable to increase the network capacity. Thus, the must-have ports on C/DWDM Mux should include line ports used to connect the outside fibers with the fiber Mux Demux and channel ports for multiplexing and demultiplexing different wavelengths.

Line Port

Line port, also called common port, is one of the must-have ports for each C/DWDM channel multiplexing and demultiplexing. There are dual fiber and single fiber types of line port, and which to select depends on the use of WDM wavelengths. The dual-fiber Mux Demux uses the same wavelength for dual-way transmission, which means the TX port and RX port of every duplex channel port supporting the same wavelength. But for a single-fiber WDM Mux Demux, the TX port and RX port of every duplex channel port supporting two different wavelengths and all the wavelengths just flow in one direction.

The above picture shows the difference between dual fiber and single fiber line port on the 8-channel DWDM Mux Demux. It is worth mentioning that sometimes the line port of single-fiber WDM Mux Demux is made into a duplex port, but only one of the interfaces is functional. You can also take the example in the third part of the above picture. It shows that the single-fiber CWDM Mux Demux has a duplex line port, but one of the interfaces marked as "N/A" is not in use.

Channel Port

Channel port is another must-have port, which transmits and receives the signals on specific WDM wavelengths. For example, CWDM technology uses 18 wavelengths ranging from 1270nm to 1610nm with a channel space of 20 nm, and the channel port count on CWDM Mux Demux is always ranging from 2 to 18 channels. While DWDM technology adopts the wavelength ranging from 1470nm to 1625nm usually with channel space of 0.8 nm (100 GHz) or 0.4 nm (50 GHz), thus DWDM Mux Demux can support much more wavelengths which has channel ports usually ranging from 4 to 96 for multiplexing more signals and achieving much higher capacity.

Function Ports on CWDM/DWDM Mux Demux

Except for the must-have channel port and line port, WDM fiber Mux Demux can also be added with other ports that bring more profits to the existing WDM network. The following will introduce these special ports that are often added on C/DWDM Mux Demux.

Expansion Port

Expansion port on WDM fiber Mux/Demux is design for adding more wavelengths or channels to the existing network. If you install a CWDM network that just uses four CWDM wavelengths, you can use this expansion port to increase the network capacity by connecting the expansion port with the line port of another CWDM Mux Demux for supporting different wavelengths. Then the capacity of the existing CWDM network can be increased easily as shown in the following picture.

Monitor Port

Technicians always choose to add a monitor port on the CWDM/DWDM Mux Demux for better network monitoring and management, which offers an easy way to test the dB level of the signal without service interruption. If you choose a single-fiber WDM Mux Demux, the monitor port should be a simplex fiber optic port. For dual-fiber WDM Mux Demux, you can add a duplex monitor port for the whole network monitoring, or just add a simplex port for Mux or Demux monitoring. Here shows a typical point-to-point network with the use of 40CH DWDM Mux Demux where two switches are connected over DWDM C51 wavelength and an optical power meter is used to monitor the power on fibers connecting the site A and B.

1310nm Port and 1550nm Port

1310nm and 1550nm are just WDM wavelengths. How do they become special? It can be recognized that the channel ports on WDM fiber Mux Demux can only be connected to color-coded fiber optic transceivers like C/DWDM SFP+. But with the special design of 1310/1550nm port, the signal running through ordinary fiber optic transceivers transmitted over 1310/1550nm can also be combined together with other C/DWDM wavelengths. Here offers a case on how to achieve 500Gbps at the existing 40-channel DWDM fiber link with a 1310nm port.

In this case, we firstly plug the 100G fiber optical transceiver over 1310nm wavelength into the terminal equipment, and then use a length of the fiber patch cable to connect it to the existing DWDM network via the 1310nm port on the DWDM Mux Demux. Since the 1310nm ports on both sides are combined into the 40-channel DWDM Mux Demux, this fiber link allows the transport of up to 40x10Gbps through channel ports plus 100Gbps through 1310 ports, which is total 500Gbps.

Besides, it should be noted that DWDM Mux Demux can only add the special 1310nm port and CWDM Mux Demux can not add all the CWDM wavelengths. The following table shows the rule about how to add the special ports and other standard channel ports on CWDM Mux Demux at the same time.

Special Port Other Channel Ports Can be Added
1310nm port

1390 nm, 1410 nm, 1430 nm, 1450 nm, 1470 nm, 1490 nm

1510 nm, 1530 nm, 1550 nm, 1570 nm, 1590 nm, 1610 nm

1550nm port

1270 nm, 1290 nm, 1310 nm, 1330 nn, 1350 nm, 1370 nm

1390 nm, 1410 nm, 1430 nm, 1450 nm, 1470 nm, 1490 nm

1310nm & 1550nm port 1390 nm, 1410 nm, 1430 nm, 1450 nm, 1470 nm, 1490 nm


From all the above, there are five main and commonly-used types of C/DWDM Mux Demux ports, each of which has its special function or usage. Knowing more about their function is very helpful in CWDM, DWDM and even DWDM over CWDM network design and deployment. If you have any C/WDM equipment demand but don't familiar with their functions or don't know how to design the network solution, welcome to visit our website www.fs.com. We supply all the mentioned ports on C/DWDM Mux Demux and other series of C/WDM equipment to satisfy the optical network needs. And customer services are also available.

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