How Does Fiber Internet Work?

How Does Fiber Internet Work?

The internet loves to take advantage of as many ways of traveling as it can: through the air, through telephone lines, underground wires, and even satellite waves. But most travel by a type of wire: DSL by telephone lines above ground; Cable by underground cable TV lines; and Fiber by fiber-optic underground wires. 

Of those 3, fiber internet is far faster and more reliable than DSL and cable – but is it worth it for you to check out? And how does it work, anyway? 

What is fiber internet?

Provider Download/Upload speeds View plans
Verizon Fios 100-940Mbps / 100-880Mbps View plans
AT&T Fiber 100-1,000Mbps / 100-1,000Mbps View plans
CenturyLink (Gigabit) 1,000Mbps / 1,000Mbps View plans
Frontier FiOS 50-1,000Mbps / 50-1,000Mbps View plans

The shortest explanation is that fiber internet uses fiber-optic cables to send data to and from your connected devices. It does this with light instead of electricity – which is how DSL and cable internet operate. 

But that doesn’t explain much. Fiber-optic cables are composed of millions of miniscule, hair-like strands of glass and plastic all bundled together. These tiny little strands transmit  using pulses of light the 0s and 1s that make up your cat videos. 

Light is ridiculously faster than electricity at doing this, which means fiber internet is lightyears (get it?) faster than cable or DSL. 

Plus, while electrical signals deteriorate the farther they get from the source, the light signals traveling on fiber-optic cables do not. That means faster speeds are available farther away. 

Types of fiber internet

Once these pulses reach the end of the line, they hit an Optical Network Terminal (ONT) that converts the light pulses into electricity, where it can connect to your device. 

However, there are a few different ways that internet service providers (ISPs) go about making this transition, which can affect the speed you actually get in some cases. 

  • FTTP: Fiber-to-the-Premise, also called to-the-Home (FTTH), -Business (FFTB), or -Desktop (FFTD) is the closest thing to a “pure” fiber network possible. The fiber-optic cable goes all the way to your home, business, or etc. There are no cable wires necessary – this is true fiber internet. Few providers (Verizon Fios being one) offer this type.
  • FFTB: Fiber-to-the-Building is similar to FTTP in that it goes to one building. However, that’s where the similarities end. Once the fiber-optic cable reaches the building, it switches over to copper coaxial wiring (cable) to be distributed throughout the structure. It’s a popular method for apartment buildings, schools, hotels, and buildings that generally cater to multiple businesses/parties under one roof. It is not pure fiber, since it switches over to copper at the end.
  • FTTN: Fiber-to-the-Neighborhood/Node is also called Fiber-to-the-Cabinet/Curb (FTTC), Fiber-to-the-Street (FTTS), or Fiber-to-the-Loop (FTTL). With FTTN, fiber’s destination is what’s called a “street cabinet” that exists about 1,000’ away from the farthest premise in a neighborhood. From there, the internet is delivered to individual houses and buildings with copper coaxial cables. It’s the most common type of fiber-optic internet connection. 


Fiber vs Cable Internet

Approximate size in MB 100Mbps (cable) 1,000Mbps (fiber)
4-Minute song 4MB 0.3s 0.03s
5-minute video 30MB 2.5s 0.2s
9-hr audiobook 110MB 9.2s 0.9s
45-min HDTV show 600MB 50s 5s
2-hr HD movie 2.5-4.5GB 4.5m 25s

*All estimates from

With all that said, how do cable internet and fiber-optic internet differ? Let’s explore in more depth. 


We’ve already briefly discussed this: cable internet sends electrical signals through underground copper coaxial cables to provide internet to your home. These are the same cables that have provided cable TV for decades. 

Fiber-optic uses a different type of cable, composed of strands of plastic and glass that transmit data using light pulses instead of electricity. 


Fiber internet is more reliable than cable, too – but only slightly. Both use underground cables, so neither is easily affected by weather. However, cable internet, since it uses electricity, is more impacted by power outages. 

Although FFTB and FTTN may be similarly affected due the partial cable network, true fiber-optic internet is less affected by electricity outages since it relies on light. 

Plus, light pulses are able to travel further without losing speed; electricity diminishes the farther it has to travel, leading to slower speeds for those farther away from the source of the signal. 


Fiber-optic and cable networks are both able to provide high speed internet, but fiber has a few distinct advantages over cable: 

  1. Higher speeds over greater distances;
  2. Symmetrical upload speeds;
  3. No slow-downs during peak usage. 

To start with, fiber-optic is capable of reaching high top speeds – to the tune of 1,000Mbps (1Gbps); but even more importantly, it can offer these faster speeds over greater distances than cable. Light travels faster and farther than electricity. 

And while cable’s upload speeds have a high-end cap of around 100Mbps, fiber is able to provide symmetrical upload speeds – i.e. the same upload speed as your download. That’s especially important if you upload large files, livestream, or work from home. 

Finally, cable internet operates on a shared network – everyone with that ISP in your neighborhood is sharing bandwidth from the same line. That means that during peak usage (morning and evening, usually), when everyone is on the web, you’re going to have slower internet. 

Not so with fiber – lots of people hopping on the same network at the same time doesn’t slow it down. 


Cable wins out when it comes to availability, though – there’s around 89% coverage.  Fiber, by contrast, only covers about 30% nationwide

A big part of this is cost: copper coaxial cables are already in place from old TV lines, so it’s a relatively simple matter to use them for internet. 

Fiber-optic, however, involves installing an entirely new infrastructure – and that’s expensive. At present it’s limited to areas on the east coast and in major cities.  


Fiber internet is actually pretty comparable in price to cable nowadays, at least on a monthly basis. You may have to pay higher up front fees for installation and activation, though. 

Fiber vs DSL

Approximate size in MB 20Mbps (cable) 1,000Mbps (fiber)
4-Minute song 4MB 1.5s 0.03s
5-minute video 30MB 13s 0.2s
9-hr audiobook 110MB 46s 0.9s
45-min HDTV show 600MB 4m 5s
2-hr HD movie 2.5-4.5GB 32m 25s


DSL – Digital Subscriber Line – uses existing telephone lines to deliver internet with electricity. Unlike old-school dial-up, DSL uses a different frequency that allows both phone and internet to travel the same wire simultaneously. 

There are actually 14 different types, but only 2 concern us: ADSL and VDSL.

ADSL is Asymmetric Digital Subscriber Line; download and upload speeds are asymmetric (like cable). VDSL is Very-High-Bit-Rate Digital Subscriber Line, and while download/upload speeds are still asymmetric, overall speed is faster. VDSL is the newest type. 


Fiber-optic has a more clear advantage over DSL than against cable. DSL, being aboveground, it susceptible not only to power outages, but also to weather: if a storm knocks a telephone pole over, the whole system beyond that pole goes down, including internet. 

In addition, like cable, DSL results in slower speeds the farther away from the source of the signal you are; again, not so with fiber internet. 


DSL is much slower than either cable or fiber internet. While some places may get speeds up to 100Mbps from DSL (typically the lowest fiber-optic speed offered), most do not. Even if you get 100Mbps from DSL, a comparable fiber-optic plan offers symmetrical upload speeds - i.e. 100Mbps download, 100Mbps upload. 

DSL’s upload speeds, in contrast, would top out around 10Mbps or so.


DSL beats out both fiber and cable for coverage, however. With 90% availability nationwide, DSL is the undisputed champ at present. DSL is especially available for those living beyond city limits – i.e. in rural regions where there’s no cable or fiber infrastructure to reach them. 


DSL is typically much cheaper than fiber-optic internet, although you will find some plans with similar (or potentially worse) pricing. AT&T Internet, for example, offers broadband (DSL) plans of 10-100Mbps for $50 a month. AT&T Fiber’s 100/100Mbps fiber-optic plan starts at a similar rate. 

The speed you get depends on where you’re located, so value-for-money could go either way. 

The disadvantages of fiber internet

We’ve touched on some issues surrounding fiber internet, but let’s talk a little more about them. There are 2 primary issues, as we see it: availability/infrastructure and necessity. 

Limited availability/costly infrastructure

These two are nearly one-and-the-same in our minds. To start with, as mentioned earlier, true fiber-optic internet is only available to about 30% of the population. That’s ⅓ the availability of either DSL or cable internet – a major problem for fiber. 

Plus, that availability is generally limited to the east coast. 

Fiber-optic lines require a completely new infrastructure to be placed – and since all of that is underground, it’s expensive to lay new lines. And the internet companies have to handle that upfront cost themselves, so it’s not very practical. 

Until providers start taking on that risk to lay down new networks, or another arrangement is figured out, fiber internet is likely to remain highly-limited to major metropolitan regions only for the foreseeable future.

Necessity for the speeds

In all honesty, you probably don’t even need those speeds – not unless you’re a 4K-streaming fanatic, livestreaming pro, or move massive files often. 

According to the FCC, most people only need around 1Mbps for general computer use and around 8-10Mbps for videos and file downloads. Even Skyping only requires about 1Mbps for SD, and as little as 1.5Mbps for HD. 

Granted, you might not want to be at the limit of your speeds for things you do a lot – but most people simply don’t need that. You can check out our guide to the best internet for streaming or the best internet for gaming to find out more about what speeds you actually need for those uses. 

Should I get fiber internet?

For a lot of people, fiber internet is simply going to be excessive. The FCC says the most you need for streaming video or music is around 25Mbps (again, check out our guide to streaming for more). But if that’s the case, then who the heck needs it? Should you get it? 

As a basic rule, if your household loves HD or 4K streaming, online gaming, and you have access to fiber internet – then yes, you probably should. You’ll pay around the same or better than for cable, and for faster speeds – both download and upload. 

But at a glance, you should probably get fiber internet if: 

  • You upload large/a lot of files on the internet;
  • You game online/live stream your gaming sessions;
  • You work remotely;
  • You livestream often;
  • You Stream HD or 4K video and music;
  • You have a lot of roommates – especially ones that like to do any of the above.

How to get fiber internet

So you’ve read our guide, you’ve decided you need fiber internet – how do get it? 

Step 1: See what’s available in your area

Use this tool to enter your zip code and see if there are any fiber providers in your area.

Step 2: Compare providers

If there’s only one fiber internet provider in your area, then skip this step; but if you have more than one to consider, use our reviews to compare them and see what’s best for you:

Step 3: Order

Last step is to order. Depending on the provider, you may get installation for free if you order online. If that’s not a promo, though, consider calling – speaking to a live person may help you get some discounts. 

Luke Pensworth Written by: Luke Pensworth


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