Different Ports on WDM Mux/Demux

In the WDM (wavelength-division multiplexing) system, CWDM (coarse wavelength-division multiplexing) and DWDM (dense wavelength-division multiplexing) Mux/Demux (multiplexer/demultiplexer) modules are often deployed to join multiple wavelengths onto a single fiber. Multiplexer is for combining signals together, while demultiplexer is for splitting signals apart. On a WDM Mux/Demux, there are many kinds of ports for different applications. This article will discuss the functions of these ports on WDM Mux/Demux.

WDM Mux/Demux

Necessary Ports on WDM Mux/Demux

Channel port and line port are the necessary ports to support the basic function of WDM Mux/Demux to join or split signals in the data network.

Channel Port

A WDM Mux/Demux usually has several channel ports on different wavelengths. Each channel port works for a specific wavelength. Since there are 18 wavelengths of CWDM ranging from 1270 nm to 1610 nm with a 20nm interval, the number of channel ports on CWDM Mux/Demux also ranges from 2 to 18. DWDM has a more dense wavelength spacing of 0.8 nm (100 GHz) or 0.4 nm (50 GHz) ranging from S-Band to L-Band around 1490 nm to 1610 nm. The number of DWDM Mux/Demux channel ports is about 4 to 96 for high-density networks.

Line Port

Each WDM Mux/Demux will have a line port connecting to the network backbone. Combined channels are transmitted or received at the line port. In addition, line port can be divided into dual-fiber and single-fiber types. Dual-fiber line port is used for bidirectional transmission, therefore the transmit and receive port in each duplex channel must support the same wavelength. However, single-fiber line port only support one direction data flow, thus the transmit and receive port of duplex channel will support different wavelengths. The wavelengths’ order of single-fiber WDM MUX/DEMUX should be reversed at both side of the network.

Special Ports on WDM Mux/Demux

Apart from the necessary ports, some special ports can also be found on WDM Mux/Demux for particular needs.

1310nm Port and 1550nm Port

1310nm and 1550nm ports are certain wavelength ports. Since a lot of optical transceivers use these two wavelengths for long-haul network, adding these two ports when the device does not include these wavelengths is very important. CWDM Mux/Demux can add either type of wavelength ports, but the wavelengths which are 0 to 40 nm higher or lower than 1310 nm or 1550 nm cannot be added to the device. However, DWDM Mux/Demux can only add 1310nm port.

Expansion Port

Expansion port can be added on both CWDM and DWDM Mux/Demux modules. This is a special port to increase the number of available channels carried in the network. That is to say, when a WDM Mux/Demux can not meet all the wavelength needs, it is necessary to use the expansion port to add different wavelengths by connecting to another WDM Mux/Demux’s line port.

Monitor Port

Monitor port is used for signal monitoring or testing. Network administrators will connect this port to the measurement or monitoring equipment to inspect whether the signal is running normally without interrupting the existing network.

ports on WDM mux demux


From this post, we can know that a WDM Mux/Demux has multiple types of ports. Channel and line ports are integral ports for normal operation of the WDM Mux/Demux. 1310nm port, 1510nm port, expansion port and monitor port are used for special requests of the WDM application. Hence, you should have a thorough consideration of your project before choosing the WDM Mux/Demux module.

Functions of ONT and OLT in GPON Network

Gigabit passive optical network (GPON) is a point-to-multipoint access mechanism providing end users with the ability to consolidate multiple services onto a single fiber transport network. To realize this technology, many devices are used to support the network, such as optical splitter, ONT, OLT, etc. In this article, we will mainly discuss the functions of ONT and OLT in GPON network.


Functions of ONT

Optical network terminal (ONT) is an optical modem that connects to the termination point with an optical cable. It is used at end user’s premise to connect to the PON network on one side and interface with the user on the other side. Data received from the customer end is sent, aggregated and optimized by the ONT to the upstream OLT. ONT is also known as optical network unit (ONU). ONT is an ITU-T term, while ONU is an IEEE term. They both refer to the user side equipment in GPON network. A small difference between them might be the application locations. ONU can work in different temperature and weather conditions.


Functions of OLT

Optical line terminal (OLT) is the endpoint hardware equipment located in a central office of the PON network. Its basic function is to control the float information in optical distribution network (ODN) to go in both directions. OLT converts the standard signals used by fiber optic service (FiOS) to the frequency and framing used by PON system. In addition, it coordinates the multiplexing between the ONT conversion devices. There are two float directions for OLT system. One is the upstream direction to distribute different types of data and voice traffic from users. The other is the downstream direction which gets data, voice and video traffic from metro network or from a long-haul network and sends it to all ONT modules on the ODN.


How to Add or Delete ONT on OLT?
Way to Add ONT on OLT

If the password of an ONT is obtained, you can run the ONT add command to add the ONT offline. However, if the password is unknown, you can run the port portid ont-auto-find command in the GPON mode to enable the ONT auto-find function of the GPON port, and then run the ONT confirm command to confirm the ONT. When the ONT is added, you need to run the display ONT info command to see the current status of ONT. If the control flag is active, run state is online, config state is normal, and match state is match, then the ONT adding process is successful.

Way to Delete ONT on OLT

When you need to delete the ONT on OLT, please use the delete command. Then ONT configuration data is deleted with the deletion of the ONT and the online ONT is forced offline. ONT can’t be deleted when it has been configured with other services. You need to unbind the service first before delete the ONT.

How to Troubleshoot ONT?

To troubleshoot the ONT, you should remember that the most important step is to connect your computer directly to the ONT to see if the problem goes away. You can use the Ethernet cable for connection. If the problem still exists, you can reconnect the ONT power supply to clear its internal cache. If the network can not be restored after the above methods, maybe you need to consult professionals for help.


ONT and OLT are indispensable components in the GPON network system. If you are considering to purchase the ONT or OLT devices, FS.COM is a good place to go. Different types of ONT and OLT equipment are provided with high integration, flexible adaption and great reliability to meet all your requirements.

Importance of Plug Boot For RJ45 Cables

Ethernet cables with RJ45 connectors are widely applied to our life. When choosing the RJ45 cables, you may discover that these cables have different appearances of their cable plugs. For example, some cables will have a rubber thing on the clip while some don’t. Why do RJ45 cables have such design and what is the function? This post is going to present the basic knowledge about the special design.

What Is Plug Boot?

This rubber thing is known as plug boot. A booted cable has the plug boot on the cable end of the connector. You can find two main types of boots on the market. One is the separate boot that can be purchased individually to put on the cable, and the other is the injection molded boot to be bought together with the cable. Of course, the latter is more stronger to provide support for the cable when the connector is being pulled out of a switch, patch panel or other devices. Non-booted cables will not have the plug boot as the protection, which are easier to be damaged.

booted cable

Functions of Plug Boot

Generally speaking, the boot design has two purposes. Firstly, the plug boot can prevent the connector clip from flipping up or even breaking off from the cable. When the plastic clip is broken, cable won’t be able to firmly connect to the network which will then interrupt the data transaction. Secondly, using the booted cable is also a protection for your own nails. Because the clip is slim and small, it is easy to stick into the nails during the installation or removal of RJ45 cable. Hence, for the better protection of both cable connector and your nails, Ethernet cables with plug boots are a great solution.

Several Types of Boots

If you want to buy the booted cables, you should also consider which type of boot is best fit for your network since plug boot also has different constructions. Here will introduce the common types of plug boots.

Standard Boot

The standard boot looks like the half of a dome. It protects the clip on all sides and prevents it from snagging or breaking off. This is the type widely applied to cable installation through floors or walls.

standard boot

Molded Boot

Molded boot does not protect the locking clip. It is easy to plug in and out. This type of boot is suitable for hard-to-access space where cables are seldom plugged or unplugged.

molded boot

Snagless Boot

Snagless boot has a small flap to protect the RJ45 clip. It is often used in applications where there are high insertion cycles in easy-to-access space.

snagless boot

Slim Boot

Slim boot has a 28% reduction in diameter than the snagless boot. It offers the minimal protection and is easy to plug or unplug. This type of booted cable is usually seen in high-density applications.

slim boot

No Boot

Non-booted RJ45 cable is much easier for plugging or unplugging, but the whole connector is exposed with no protection. This type is typically used for applications that don’t require frequent unplugging.

no boot


In summary, if you want to have better protection for your Ethernet cables, using plug boots is an ideal solution. If the application does not demand too much cable shifting, non-booted cables are also acceptable. No matter which type of RJ45 cable you choose, the decision must be made according to your own project.

Have You Chosen the Right Power Cord?

Different cables have particular applications. Some are used for data transmission like fiber optic cable or copper cable, and some are used for the transmission of electrical power. Power cord is the assembly widely used as the connection between main electricity supply and the device through a wall socket or extension cord. Power cord is adopted in almost every where when the alternating current power is required. However, have you chosen the right type of power cord for your device? From this article, you may find the answers.

power cord

Overview of Power Cord

A power cord set usually has connectors molded to the cord at each end, thus both ends can detach from the power supply and device. Specifically, power cord assembly consists of three major parts. First is the cable plug, and it is also a male connector used for inserting into the AC outlet to provide power. Then is the receptacle on the other end. Receptacle part is also known as the female connector attached to equipment. Cord is the main section that contains the insulated wires with different lengths and thicknesses.

power cord structure

Common Types of Power Cord

According to different plug and receptacle styles, power cords have different standards. In North America, NEMA power cords and IEC 60320 power cords are the common types with the standards set by NEMA (National Electrical Manufacturers Association) or IEC (International Electrotechnical Commission). Let’s have a look at their differences.

NEMA Power Cord

NEMA power cords have two series of NEMA 5 and NEMA 6. NEMA 5 series is the type widely found in the United States. It has three-wire circuits (hot, neutral, and ground) and is rated to carry a maximum of 125 volts although usually carries about 110 volts and are referred to as “110 circuits”. NEMA 6 series connectors are used for providing heavy duty power to a device. These are typically 208 volt or 240 volt circuits and often referred to as “220 circuits”.

NEMA Power Cord

IEC 60320 Power Cord

The ends of IEC 60320 power cord are on the opposite side of the cord from the power plug. To make it an international standard, the equipment manufacturers need to put one kind of receptacle on their equipment and then manufacture the various country-specific cords when needed. The IEC 60320 C13/C14 connector type is seen on most personal computers and monitors. C19/C20 connector type is used for devices like servers and UPS (Uninterruptible Power Supply) systems.

IEC 60320 power cord

How to Organize Power Cords?

Just like other types of cables, too many power cords can also be easily mixed up during work. Fortunately, there is a simple way to organize the power cords. Instead of labeling all the power cords, you can buy the colored cords for identification. For example, red power cords can be used for important device, and green or blue cords can be used for constantly rearranged equipment. Color coding the system is definitely a more efficient way for cable management.

colorful power cord


The standardization of power cords provides great help for the convenient connectivity when powering different kinds of devices. There is usually a long list of power options for the switch or server. You might be confused when all the components are using the acronyms you don’t know. Therefore, understanding the standards can make the selection of power cords much easier.

Data Center Architecture Designs Comparison: ToR Vs. EoR

The interconnection of switches and warranty of data communication are the basic aspects to consider when designing a data center architecture. Today’s data centers have been shifted into 1RU and 2RU appliances, thus setting the 1RU and 2RU switches into the same-sized racks can greatly save space and reduce cabling demands. Typically, Top of Rack (ToR) and End of Row (EoR) are now the common infrastructure designs for data centers. In this article, we will mainly discuss the differences between these two approaches.


Overview of ToR & EoR
What Is ToR?

ToR approach refers to the physical placement of network access switch in the top of a server rack. Servers are directly linked to the access switch in this method. Each server rack usually has one or two access switches. Then all the access switches are connected with the aggregation switch located in the rack. Only a small amount of cables are needed to run from server rack to aggregation rack.


What Is EoR?

In the EoR architecture, each server in individual racks are directly linked to a aggregation switch eliminating the use of individual switches in each rack. It reduces the number of network devices and improves the port utilization of the network. However, a large amount of cables is needed for the horizontal cabling. Along with the EoR approach, there is also a variant model named as MoR (Middle of Row). The major differences are that the switches are placed in the middle of the row and cable length is reduced.


Comparison Between ToR & EoR

As for ToR, the cost of cables are reduced since all server connections are terminated to its own rack and less cables are installed between the server and network racks. Cable management is also easier with less cables involved. Technicians can also add or remove cables in a simpler way.

In the EoR, device count is decreased because not every rack should equip the switches. Thus, less rack space is required in the architecture. With less devices in data center, there will be less requirements for the cooling system which also reduces the using of electricity power.


In reverse, there are also some limitations for each architecture. For ToR, although the cables are reduced, the number of racks is still increased. The management of switches may be a little tricky. In addition, ToR approach takes up more rack space for the installation of switches.

As for EoR, its Layer 2 traffic efficiency is lower than the ToR. Because when two servers in the same rack and VLAN (virtual local area network) need to talk to each other, the traffic will go to the aggregation switch first before comes back. As less switches are used in EoR design, more cables are deployed between racks triggering higher possibility of cable mess. Skillful technicians are required when carrying out the cable management.

Physical Deployments of ToR & EoR
ToR Deployment

One is the redundant access switch deployment which usually demands two high-speed and individual ToR switches that connect to the core network. Servers are interconnected to access switches deployed within the server racks. Another is the server link aggregation with ToR deployment. Two high-speed ToR switches are part of the same virtual chassis. Servers can connect to both of the switches located at top of rack with link aggregation technology.

EoR Deployment

EoR access switch deployment is very common to extend all the connections from servers to the switching rack at the end of row. If the deployment is needed to support the existing wiring, you can also deploy a virtual chassis.


ToR and EoR are the common designs for data center architecture. Choosing the proper one for your network can promote the data center efficiency. From this article, you may have a general understanding about these two methods. Hope you can build up your data center into a desired architecture.