Basic Knowledge & Tips of Data Center Cabling

With the benefits of fiber optic cable, they are widely used in data centers around the world nowadays. Fiber optic cables seem to be an indispensable component of each data centers. They play an important role in transmitting data every moment with a fast speed. In order to avoid unnecessary loss or keep safety, whether you are a novice or a veteran, it’s important to understand the basic knowledge before you begin fiber cabling in the data center.

data center cabling

Basic Knowledge Of Fiber

As we know, in fiber optic cables, data is transmitted through pulses of light and this digital signal is transmitted over a medium made of high-quality glass. Due to the diversity of fiber cables, the most basic knowledge of fiber optic that you should understand is the difference between single-mode and multi-mode fiber when considering fiber optics for your data center.


Single-mode Fiber

SMFSingle mode fiber is a single strand of glass fiber with a core diameter between 8 and 10.5 μm and a cladding diameter of 125 μm that has one mode of transmission. Due to its relatively narrow diameter and one mode, it will propagate typically 1310 to 1550nm while only the lowest order bound mode can propagate at the wavelength of interest typically 1300 to 1320nm. Single-mode fiber usually carries higher bandwidth and gives a higher transmission rate and up to 50 times more distance than multi-mode fiber, but requires a light source with a narrow spectral width that is also cost more. We usually see the 9/125 in construction which means that the core to cladding diameter ratio is 9 microns to 125 microns.

Multi-mode Fiber

MMFMultimode fiber is made of glass fibers, with a common diameter in the 50 to 100 μm range for the light carry component (the most common size is 62.5). Due to its large diametral core, multi-mode fiber allows multiple modes of light to propagate. Light waves are dispersed into numerous paths, or modes, as they travel through the cable’s core typically 850 or 1300nm. Using multi-mode fiber, you can get high bandwidth at high speeds (10 to 100MBS – Gigabit to 275m to 2km) over medium distances. However, there is a limitation of multi-mode fiber. Because of the high dispersion and attenuation rate with this type of fiber, the quality of the signal is reduced over long distances. Multimode fiber is usually 50/125 and 62.5/125 in construction which means that the core to cladding diameter ratio is 50 microns to 125 microns and 62.5 microns to 125 microns.

After understanding of the single-mode fiber and multi-mode fiber, you may have a question:

When considering fiber optics for your data center, which type is better?

To this question, my question is “the best systems are the ones that work well for you”. This is based on transmission distance to be covered as well as the overall budget allowed. Multimode fiber will allow transmission distances of up to about 10 miles and will allow the use of relatively inexpensive fiber optic transmitters and receivers. If the distance to be covered is more than 10 miles, single mode fiber is the choice. However, transmission systems designed for use with this fiber, such as the laser diode will typically cost more.

Note: It is important to never mix fiber optic cores. For example, never plug a single-mode 9/125 cable into a multi-mode 50/125 cable or plug a multi-mode 50/125 cable into a multi-mode 62.5/125 cable. When cores are not matched properly, data transmissions will be lost. Other cable information depending on the application, such as fiber patch cord, horizontal and backbone cables can be learned if you are interested, here is not to state one by one.

Best Practices For Better Fiber Cabling

We have a basic understanding of fiber optic cables in the first section. This part, we will go to give some practical tips of fiber cabling. Though fiber cabling has distinct benefits compared with copper in regard to transmission, attenuation and electromagnetic interference (EMI), improper practices of fiber cabling may lead bad effect to data transmission. Therefore, we must maintain the best practices when we doing fiber cabling.

Inspection & Cleaning

fiber microscope fiber cleaningMaybe you have heard a saying that best practices for fiber optic installation start with inspection & cleaning. They are growing in importance as links with increasingly higher data rates are driving decreasingly small loss budgets. With less tolerance for overall light loss, the attenuation through adapters must get lower and lower. This is achieved by properly inspecting and cleaning when necessary. There are two types of problems that will cause loss as light leaves one end-face and enters another inside an adapter: contamination and damage. In general, we do the inspection with fiber microscope (optical microscope or video microscope). It is easy to use but be sure to follow the instruction. In addition, you must beware of bad habits when you doing cleaning. Because cleaning has been part of fiber maintenance for years, most people have their own approaches for cleaning end-faces. However, beware of bad habits as many have developed in the industry over time. In a word, whatever approach is selected, certain truisms apply to fiber optic end-face inspection and cleaning. Strictly follow the defined working process and principles and consistent inspection and cleaning up front will avoid unexpected and costly downtime in the future.

Fiber Bend Radius

bend radiusThere is a reduction in the strength of that signal when a cable is bent. Similarly, fiber optic cables are also as. The bend radius, or measurement of a curve, can determine how strong the data signal will flow. With fiber cabling, there are different specifications for bend radius varying by cable manufacturer and fiber type. There have been many improvements made in this area, including the development of “bend insensitive fiber“. A good rule of thumb for determining bend radius during installation is that bend radius equals 10-15 times the outer diameter of the cable jacket. You can also consult the manufacturer for recommendations when you choosing cables.

Pulling Fiber

In many cases, fiber cabling must run over long distances. Although fiber optic cabling assemblies are robust and sturdy, it needs to be cautiously used when pulling. It is important to remember that never pull from the connectors because this position is typically the weakest link in pulling strength. In addition, we suggest you to use a pulling sock to reduce strain on critical areas. It is readily available from the related suppliers.

pulling fiber

Tie-down points

When you doing some cable management, you will face the question “How to confirm the correct tie-down point?”. The tie-down point, here we mentioned, is the area where the cable is affixed to patch panels or racks and cabinets to ensure they do not move around. To tie-down the fiber cable properly, you may never use zip ties on fiber optic cable unless there are specifically designated areas on the cable to do so. The common and proper way is to use Velcro and never over tighten, as this can crack the fiber and cause failure. The following picture shows us the improper and proper ways to tie-down fiber.


Labeling Is Necessary

patch panel labelCable labeling makes jobs become easier and safer. They are designed to help users reduce trouble, improve safety and save time and money. Every cable in your cable room should be clearly labeled so you can trace any faults. Your business can’t afford to waste time testing cables at random to find a fault when the system is down. Proper data center cabling by an experienced network cabling service would include this as a routine matter. Of course, you should obey the rules of labeling but not just do it casually. Also, it seems simple, but it has its own skill requirement and meaning in the data center.

Fiber cabling in the data center is not as simple as the above statement, except them, there are much other knowledge or operating skills to learn during working. The knowledge described above is the most basic knowledge which is for reference only.


As data rates keep increasing, fiber optic cable will become more necessary for many data center applications. A thorough understanding of the basics will help you work better and higher efficiency. I hope you will enjoy this article and gain some help or working inspiration from it. In addition, if you have any requirement about the related products, such the fiber cables, fiber patch cord, fiber patch panel or other fiber optic products, you can visit our website or contact us directly over

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