The Introduction of Multi-Fiber Cables in the Data Center

A long time ago in a data center far away, only a few fiber connections were needed. Over the years, the need for data has increased. And “increased” is an understatement. The need for data ports in the data center has grown exponentially, skyrocketed, blown up, and just got plain out of hand! With this increase, the technology and construction of fiber cabling has also changed just as dramatically.

This brings us to our blog topic of multi-fiber cables in the data center. In plain language, multi-fiber cables are just that: cables with multiple fibers in them. They’re also referred to as fiber optic trunks. In the past, fiber optic “jumpers” or patch cords have been used to connect hardware. The patch cables are essentially single connection points with two fibers inside the outer jacket. That was fine when there were only a few ports, but with the hundreds and thousands of ports data centers now contain, patch cables are an ineffective way to manage your cabling infrastructure. That is where multi-fiber cables come in!

Benefits of Multi-Fiber Cables in the Data Center

Since fiber optic cabling is not affected by cross talk or outside interference, the fibers can be condensed into groups that greatly reduce the overall footprint of the cable. This means a lot in a data center, where space is at a premium. It blocks less air from the CRAC (Computer Room Air Conditioner), thus improving the energy efficiency dramatically. Multi-fiber cables also reduce installation and maintenance time by making cable identification easier. Fiber optic trunks, or multi-fiber assemblies, are also more rugged and can withstand more abuse during installation and maintenance.

To get a better understanding of this product type, have a look at our Skinny-Trunk Multi-fiber assemblies.

Insertion loss is the amount of light lost (measured in dB) from the origination of a signal to the reception of that same signal.

What happens if insertion loss is too high?

Too high of an insertion loss will lead to what is know as “channel errors” that can cause equipment to go down and possibly cause data center downtime.

Why is knowing insertion loss important?

It is important to know the insertion loss of the products you are using or considering purchasing. Be sure to ask for insertion loss specifications before purchasing cables. Pay attention to words like “typical” versus “maximum” insertion loss.

Some manufacturers will supply statistics in typical readings or averages. This should not be considered a number to use – you may end up getting cables that are well above the average.

Instead, you should look for the “maximum” insertion loss of a product. This allows you to know the highest possible loss amounts that you will incur.

Yesterday I wrote a little bit about how data center technicians can inadvertently affect the performance of their fiber optic cabling. Today, I’ll discuss how manufacturers of fiber optic cabling can do the same. While purchasers of cabling infrastructure don’t have control over the manufacturing process, this will help guide what questions should be asked before ordering.

How Cable Manufacturers Affect Fiber Optic Cable Performance

Inferior Polishing Process

The polishing process occurs at the end-faces of the assembly, best done by a machine in a highly controlled environment. There are MANY factors that contribute to a well-polished end-face. Improper techniques and tools will lead to improper radius of curvature, undercut fiber and protrusion that is out of specification. While these terms about the manufacturing process may be unfamiliar to data center technicians, they are VERY important to an assembly’s performance and network lifespan.

Many “nightmare” problems occur from the above, and the issues don’t show themselves until after they have been plugged in multiple times. You may be familiar with the phrase “chasing ghosts” – fiber may be causing a network issue, but is not considered when troubleshooting since it was working properly upon installation.

Non-Licensed Connectors or Poor Quality Connectors

Using inferior components leads to poor alignment. Alignment is critical for fiber optic end-face mating – improper alignment leads to a reduction of light passing from mated pairs. This really inhibits the performance of your cabling infrastructure!

We recommend the MTP® connector (shown above), which is the MPO-style connector manufactured by US Connec.

Inferior Glass

Fiber optic cabling is made from glass. If there are impurities in the glass, the performance will be affected. The glass could also be weak in some areas and be more prone to cracking or splintering during installation or general maintenance, again leading to a problem that is very difficult to track down!

Many view fiber optic cable assemblies as disposable commodities. I would argue that this approach leads to costing a business entity even more money in troubleshooting and downtime than if they would have invested in a well manufactured product, and utilized best practices when installing.

When fiber cable assemblies stop working properly, it can lead to downtime. In the next few posts I will explain how and why this actually happens. This will be broken into two parts: How it happens at the end user site, and how it occurs at the manufacturer level.

How Data Center Technicians Affect Fiber Optic Cable Performance

End-Face Contamination

Fiber optic assemblies are glass. If you get glass dirty, light is not able to pass through it as effectively. In the case of fiber optic cables, light is data. You can avoid this by inspecting the end-faces of cables, and clean them if needed. Do not plug in fiber cables that could be contaminated – they will contaminate the fiber it is mated with. (Watch this Cable Talk video to learn even more about contamination and how to avoid it.)

Violating Bend Radius

Bend radius is the minimum amount you can bend a fiber optic cable. When fiber cables are bent past the recommended limitation (set by the manufacturer), data loss is incurred. Too much loss, and you will experience downtime.

Using Excessive Pull Force During Install

Well built fiber assemblies are very strong. However, it is best practice to always handle with care! There are many pieces in an assembly, and pulling on it could lead to pieces becoming separated. This could lead to the failure of that cable.

Tying Down With Zip-Ties Too Tightly in Wrong Areas

Zip-ties tend to be cinched too tightly and pinch the fiber, which could then crack and cause a serious loss in data. Only use zip-ties on furcation points of multi-fiber trunks. That area is designed to withstand the force. Or, don’t use zip-ties at all – the best practice for tying down fiber optic cables is to use Velcro (example above), which decreases your chance of pinching the fiber.

Cabling Installation & Maintenance is one of my favorite industry pubs – so I was excited to see our Skinny-Trunk assemblies featured after reaching 0.25-dB insertion loss. Check out the article here: MTP assemblies achieve 0.25-dB insertion loss per mated pair.

We’re extremely proud of reaching 0.25dB, but we’re not stopping there! The CABLExpress product team will continue to push for better and better performance out of our Skinny-Trunk fiber optic cabling solution.