Applications of Serial Transmission and Parallel Transmission in Network

In the age of the Internet, we are not unfamiliar with data communication, which refers to the process of transferring data signals between two or more devices. Basically, there are two methods used to transmit data signals: serial transmission and parallel transmission. To put it simply, serial transmission sends data bits one after another over a single channel, while parallel transmission sends multiple data bits at the same time over multiple channels. Both of them are commonly used in network applications and this article will focus on applications of serial transmission and parallel transmission in network.

serial transmission and parallel transmission

Application of Serial Transmission

As in serial transmission, bits are sent sequentially on the same channel (wire), one bit at a time, the cost for wires is low but the speed of transmission is slow. In 10G network, serial transmission is usually utilized. For example, a duplex LC fiber that consists of one fiber for transmitting 10G data signals and one fiber for receiving 10G data signals is typically used to completer the data link. In high-density network applications, it is easy to find LC duplex patch cables deployed to connect different network devices.

serial transmission for 10G network

Application of Parallel Transmission

In parallel transmission, multiple bits (usually 8 bits or a byte/character) are sent on different channels (wires, channels) simultaneously over the same cable. Compared with serial transmission, parallel transmission has a faster bit rate, and the higher cost since multiple wires cost more than one single wire. Parallel transmission is usually used in 40G and 100G network because it can transfer more data signals and achieve higher speeds. For example, MTP trunk cable, terminated with MTP/MPO fiber connector on each end, can be used to achieve the connectivity. In 40G networking applications, a 12-fiber MTP fiber connector is used: 10G is sent along each channel or fiber strand in a transmit and receive direction, and 8 of the 12 fibers are used to provide 40G parallel transmission; in 100G network applications, a 24-fiber MTP fiber connector is used: 10G is sent along each channel or fiber strand in a transmit and receive direction, and 20 of the 24 fibers are used to provide 100G parallel transmission.

parallel transmission for 40G network

Note: Parallel transmission can also be applied to 25G duplex fiber pairs to reach even higher speeds or reduce the number of fibers required at a given speed. For instance, a 100G channel would require four 25G duplex fiber pairs instead of ten 10G duplex fiber pairs.


In network applications, serial transmission is often used in 10G connectivity, while for 40G and 100G connectivity, parallel transmission is preferred. Hope you could acquire some useful information from the article, and have a better understanding of these two data transmission methods. In addition, you can find fiber optic cables mentioned above in FS.COM. Some other fiber optics are also available here, such as 24-fiber MPO MTP loopback, MTP to LC breakout cable, MPO fiber patch panel and so on. If you want to know more details, please visit our site.

How Much Do You Know About Fiber Loopback Cable?

With the widespread adoption of 40G and 100G Ethernet network, cabling system in data centers becomes more and more complicated. Choosing a suitable cabling solution is important, but ensuring the normal operation of optical components is the basic requirement. Therefore, it is necessary to carry out fiber optic testing. On the market, there is an useful tool that can provide cost-effective solution for fiber optic testing application—fiber loopback cable. Have you ever used it? How much do you know about it? This article will guide you to know more about fiber loopbackc able.

Overview of Fiber Loopback Cable

Fiber loopback cable is terminated with two connectors on each end of the cable, forming a loop. From the figure below, we can see that there is a black enclosure outside the optical cable. This improved structure is aimed to protect the cable. In addition, this design makes the fiber loopback cable more compact in size and stronger in use. Fiber loopback cable is used to provide a medium of return patch for an optical signal, especially for fiber optic testing applications and network restorations. It can determine where the fault might lie. Similar as fiber optic patch cord, fiber loopback cable can be classified according to fiber type used and fiber optic connector type. So we can find single-mode fiber loopback cable and multimode fiber loopback cable, as well as LC fiber loopback cable, SC fiber loopback cable and MTP/MPO fiber loopback cable on the market.

fiber loopback cable

Application of Fiber Loopback Cable

Fiber loopback cable is often used to check whether fiber optic transceiver operates normally. As we all know, fiber optic transceiver has two ports, a transmitter port and a receiver port. During the testing process, the fiber loopback cable directly routes the laser signal from the transmitter port to the receiver port. Then we can compare the transmitted pattern with the received pattern to make sure the transceiver is identical and has no errors. Take MPO loopback cables for example, they are mainly used for testing parallel optics, such as 40G and 100G transceivers. In addition, the MPO fiber loopback assembly cable is available in 8 fibers, 12 fibers and 24 fibers, which can be applied according to different requirements of testing applications. To have a better understanding of fiber loopback cable’s working way, here is a figure of fiber loopback cable used for testing application for you.

application of fiber loopback cable


Fiber loopback cable is designed for equipment testing, self-testing, engineering, network diagnostics and measurement applications. It plays an important role in troubleshooting in laboratories and manufacturing environments. Besides, it provides a cost-effective way to test the transmission capability and receiver sensitivity of optical network equipment. When choosing a suitable type of fiber loopback cable, we should take the connector type, polish type, and cable type into consideration.