What is fiber internet?

Fiber-optic internet, commonly called fiber internet or simply “fiber,” is a broadband connection that can reach speeds of up to 10 Gigabits per second (Gbps) in some areas.


The technology uses fiber-optic cable, which amazingly can send data as fast as about 70% the speed of light. In addition, fiber-optic cables are not as susceptible to severe weather conditions as other types of cables. These sturdy fiber cables have minimal outages as compared to others. They also resist electrical interference.


Fiber is ideal for homes or businesses with multiple users connecting several devices at once. CenturyLink Fiber service allows you to:

  • Upload and download files quickly
  • Enjoy buffer-free online gaming and video chatting 
  • Back up your entire hard drive to the cloud, including large photos and videos, in minutes instead of hours
  • Download a 2-hour HD movie in seconds, compared to waiting 30 minutes or more over a 20 Mbps DSL internet connection
Fiber internet - optical fibers

How does fiber-optic internet work?

Fiber-optic internet is a complex technology that allows the transmission of information in the form of light rather than electricity. There are many pieces that make up this advanced technology, but two key components are optical fibers and the so-called “last mile” of the fiber-optic network.

Optical fibers

Optical fibers are tiny — about 125 microns in diameter, or slightly larger than a human hair. Many of these fibers are bundled together to form cables (not to be confused with coaxial cables, which are made of copper). The optical fibers carry pulses of laser or LED light down the line, transmitting information in “binary” form, similar to the 0s and 1s used in electronics.

The last mile

Once these super-fast pulses of light reach their destination, they are converted into electrical output that your devices can understand and use. This is performed by a special piece of equipment called the optical network terminal, which then sends the signal through an Ethernet connection to the end user. The stretch between the main fiber network line and the end user is referred to as the “last mile” (though it is often much shorter than a mile).


“Pure fiber” refers to fiber connections that run all the way to the end user’s home, business or desktop computer. This is the fastest and most expensive “last mile” option, as it brings the full speed and reliability of fiber straight to the consumer. 


As an alternative, copper cables are often used to carry the fiber connection from a terminal called a “street cabinet” to a whole housing block, campus or residential building. This option is less expensive, but a small amount of the fiber speed is lost in the “last mile.”

2-minute history of fiber optics

Though many people think of fiber-optic as a new technology, it actually dates back to the 1970s, when it was first used in telecommunications.


In 1988, fiber-optic cables were laid beneath the ocean, connecting the U.S. to Europe. Over the years, more and more lines were laid under the sea, so today a huge network of fiber-optic cables stretches around the entire globe. Growing fiber networks, with their high-speed capabilities and reliable transmission of data, have allowed for dramatic progress in the telecom field — in fact, some say fiber-optic technology is what made the Information Age possible.


In developed nations, fiber-optic lines replaced the older copper lines years ago, forming the core or “backbone” of our current internet networks. Only recently has it become more cost-effective to install fiber lines than copper ones. So, as the technology keeps improving, fiber-optic networks are expanding rapidly across cities and directly to homes. 

How is fiber different from other types of internet?

The main difference is that fiber doesn’t utilize electric current like other types of internet connections do. It uses light, delivered through the fiber glass core.


Internet technologies have evolved dramatically over time, from dial-up connections to broadband technologies like DSL and cable.

Dial-up internet

Dial-up, which is far less common than it was 20 years ago, utilizes existing telephone lines, which are usually made of copper. Dial-up uses the audible frequency of the landline, which is why you hear a series of beeps and noises when it connects. And, you can’t use the telephone and the internet at the same time because they share the same line.


The average speed of dial-up connections is about 56 Kbps (that’s about 0.05 Mbps) for downloading and uploading.

Cable internet

Cable internet uses the same line (or at least the same type of line) that your cable TV service uses, known as “coaxial cable.”


Speeds for cable internet can vary widely, anywhere up to 940 Mbps for downloading and up to 50 Mbps for uploading, on average.

Is fiber internet faster?

High-speed internet connections transmit data at different speeds. In addition to being faster, fiber is widely considered to be more reliable, thanks to fewer outages and electrical interferences.


CenturyLink Fiber service can deliver symmetrical download/upload speeds of up to 940 Megabits per second (Mbps) over a wired connection to your router.


In thinking about speed, you can’t ignore the impact of WiFi. The everyday connection speed you experience can be limited by the use of wireless technology, which tends to lose signal strength (meaning reduced bandwidth) as compared to the wired connection that enters your router. 

What are the benefits of fiber internet?

Fiber internet is a great choice for high-bandwidth households or businesses where multiple users want to stream video, play online games, back up data, or send and receive large files at the same time.


A fiber-connected home or business can deliver an exceptional experience across all devices and internet-connected systems, from home security to smart thermostats, ovens, refrigerators and other appliances.


With faster speeds, you also don’t get as much buffering with on-demand streaming. “Buffering” refers to the loading time that occurs when a video pauses and has to catch up. Fiber Internet from CenturyLink, for instance, lets you download a full-length 4K or HD movie in seconds.


As an example, this is how long it would take, on average, to download a large media file (6.5 GB) by internet type:

Dial-up 11 days
DSL 1 - 14 hours
Cable 1 min - 14 hours
Fiber ~ 1 min

What is dark fiber?

You may have heard the terms “dark fiber” and “lit fiber” and wonder what they mean. Well, it may surprise you to learn that the biggest cost of building a fiber-optic network isn’t the cable itself, but the cost of digging up the ground to bury the cable. So, once they’ve completed the digging, many telecommunications companies lay down extra fiber-optic cables to enable future development. “Dark fiber” refers to those cables that are not yet being used, while “lit fiber” refers to the lines that are already connected (or “lit”) and are being used by telecom companies to deliver fiber internet services.

Interested in getting fiber internet?

CenturyLink is continually expanding its fiber-optic network across the country. Check availability today and see if you can get Fiber service.

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