Understanding Universal Polarity in MTP® Cabling System

Posted on Jun 12, 2023 by

Managing duplex fiber polarity is challenging when multifiber MTP®/MPO cables and fiber cassettes are the solutions in data center cabling. To solve the issue, TIA released a new Optical Fiber Cabling Component Standard, ANSI/TIA-568.3-E. The biggest change in the new standard is the introduction of two new "universal" polarity methods: U1 and U2. Then, what is universal polarity, and can different polarity types be mixed? Find answers in this article.

What is Universal Polarity?

According to the TIA standard, universal polarity can keep the correct polarity by using the same fiber patch cables and MTP® cassette types at both ends of fiber links. There is no need to inverse or reconfigure to keep the correct fiber polarity, which reduces the complexity of a fiber network and streamlines network maintenance. Methods U1 and U2 both use type B trunks and A-to-B duplex patch cables. Where they differ is method U1 uses type A (key up to key down) array adapters and type U1 fiber transitions while method U2 uses type B (key up to key up) array adapters and type U2 fiber transitions as shown below :

Connectivity Method
Trunk Cable
Array Adapter
Fiber Transition
Duplex Patch Cables

The Benefits of Universal Polarity

Compared to the previous polarity methods A, B & C, the universal polarity method is an easier deployment option for people who are not familiar with fiber polarity. For example, method A uses type A straight-through MTP® trunk cables with a key up connector on one end and a key down connector on the other end. Method B uses key up connectors on both ends to achieve the transceiver-receiver flip. Method C is very similar to method A, but each pair of fibers is flipped. With three different polarity methods and the need to use the correct type of patch cables for each, deployment mistakes can be common. The universal polarity method U1 and U2 are having the commonality components of method B without the need for unique MTP®-to-LC cassettes on each end. Customers can now use the same MTP®-to-LC cassettes and duplex patch cables on either end of the channel in conjunction with a type B trunk. The following figure is an example of the universal polarity method U1 connection. And you can also refer to Understanding Polarity in MTP®/MPO System to find more information about MTP®/MPO polarity.


Understanding Universal Polarity in MTP Cabling System

FAQs about Fiber MTP® Polarity

If you are about to design a network system by yourself or find some proper products for the company, there are some frequently asked questions that you should know in advance.

How many polarity methods are included in the standard and are they mandatory?

The Standard includes three common methods identified as methods A, B & C, and two new universal methods: U1 and U2. While many methods are available to establish polarity, this Standard outlines sample methods that may be employed. Therefore, many other polarity methods are available to accomplish the same result. Universal polarity is a new way to design your cabling system.

Can polarity types be mixed?

Unique channel design can be achieved by mixing different polarity types. It requires detailed planning, evaluation, and validation. When making additions or changes, order control and inventory management are also required.

Which polarity type should I use?

Different polarization methods can be applied according to different situations. Universal polarity provides easier options for the customers as all patch cables and cassettes are the same.

How do I make sure it's correct?

FS.com focuses on research and development, design, and system solutions in the field of network communication. At the same time, our technical experts gain an in-depth understanding of customer needs and feedback. If you have any questions about MTP®/MPO polarity validation, please contact us with no hesitation. We will ensure our products are developed for success in real-world applications.


With the continuous development of technology, the evolution of polarity management is ongoing. Universal polarity is a new way to enhance polarity management, which streamlines fiber cabling installations and maintenance. FS.com offers a wide variety of multi-fiber connectivity solutions to meet all connectivity requirements.

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