The growth of MPO adoption in the past few years is changing the game for network architectures around the world. In a previous blog, 5 Things to Know Before Working with Multi-Fiber MPO Connectors, I referenced some trends and growth projections for MPO connectivity from a recent survey by VIAVI Solutions that polled hundreds of respondents who either design or install networks with MPO connections.  With most people expecting their work with MPO to increase by over 20% in the next three years, it’s no surprise that testing MPO has become a popular topic in fiber networks of all kinds, including Wireless Carriers, Network Service Providers, Cable MSO’s, Enterprise Data Centers, Aerospace, and more.

While the previous blog introduced some key things to help technicians prepare for working with MPO, this one provides more insight from experienced technicians by highlighting some of the MPO testing challenges they are facing and how they can be overcome. At VIAVI, we constantly hear from contractors who are overwhelmed with MPO testing. They realize that using MPO connections has design and deployment advantages over typical single or duplex fiber connections but are frustrated and overwhelmed when it comes to testing multi-fiber connections. Here are the top 3 challenges that the survey respondents are facing when testing MPO connectivity:


With a typical MPO connector utilizing 8, 12, or even 24 fibers, that means that a lot more fibers are being tested in a single connector. If a traditional “single fiber” test instrument is used, then additional break-out/fan-out cable must be added that breaks out each fiber of the MPO connector at one end to individual single-fiber connectors at the other end.

The fibers are then individually tested, one-by-one. They cannot be simultaneously tested unless you use multiple test instruments (which is cumbersome and expensive).  Adding break-out cables also requires more steps in the testing process; including inspecting, cleaning, and re-inspecting end faces, performing additional referencing, and transporting additional equipment. For any contractor running a successful business, time is money, and they are finding that their “single-fiber” test tools are costing them more than they can afford.


At VIAVI, we have been actively educating the industry for years about the importance of ensuring clean fiber connections. Our “Inspect Before You Connect” message has been adopted by manufacturers, installers, and operators throughout the world. The technicians working with MPO connections are finding that these multi-fiber connectors are much more difficult to keep clean than typical single-fiber connectors like LC or SC. In our video series Essentials of Multi-Fiber MPO Testing, episode 2: Dealing with Contamination on MPO Connectors explains the reasons why MPO connectors become so easily contaminated (e.g. more fibers on the end face, a larger surface area, increased exposure to the bulkhead, etc.) and how technicians can implement proactive inspection practices using purpose built inspection tools like the FiberChek Sidewinder to quickly scan all of the fibers in a multi-fiber connector and evaluate the condition of all the fibers present.

Note from the editor: VIAVI would like to thank all the industry organizations and publications that have been recognizing FiberChek Sidewinder.  From being the 2018 Lightwave Innovation Reviews Winner in Field Test Equipment to winning the platinum-level Innovators Award from Cabling Installation & Maintenance, we are grateful to receive this elite level of recognition from the finest in our industry.


As previously mentioned, if a technician is using a traditional “single-fiber” test instrument, then they need to connect additional break-out/fan-out cables to the MPO connectors at the end of a link. In addition to the time-consuming nature associated with this, technicians find this adds further complexities to the process. These fan-out cables frequently become a tangled mess during the test process and technicians often struggle to determine which break-out strand corresponds to which fiber. Added labeling steps are often incorporated to try and mitigate confusion. In addition to labeling and identification, maintaining the performance quality over time requires proper care with end face inspection and cleaning. These cables must be treated like reference cables, but with more end faces to care for. If one dust cap gets lost, the exposed end can get damaged, making the entire cable useless.

Clearly, Multi-Fiber MPO connectors have a big future ahead. As fiber network designs are changing to support 25G, 40G, 100G, and beyond, the test solutions also need to change. While there may be ways to use legacy “single fiber” tools for MPO testing, they are just too slow, cumbersome and complex to support the testing demands while maintaining installation and service costs. For more information about Testing Parallel Optics, download our White Paper: Testing Parallel Optics or visit us online at

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