Fiber Internet: Not All Fiber Is the Same

Getting the Internet Right: Part 5 of 12

Fiber internet has become the gold standard that everyone asks for. "Can we get fiber?" is usually one of the first questions a business asks when they're shopping for internet, and for good reason. Fiber optic connections are faster, more reliable, and more consistent than anything running over copper or coaxial cable. But the word "fiber" gets used to describe several very different products, and understanding those differences is important. A business that thinks they're getting one thing and is actually getting another can end up disappointed, overpaying, or both.

How fiber works

Fiber optic cables transmit data as pulses of light through thin strands of glass. Each strand is about the diameter of a human hair. The light signals can travel long distances with almost no degradation, which is why fiber doesn't have the distance limitations that plague DSL. A fiber connection performs essentially the same whether you're 500 feet from the provider's equipment or five miles away.

The bandwidth capacity of fiber is, for all practical purposes, limited only by the equipment on each end, not by the fiber itself. A single strand of fiber can carry enormous amounts of data. When providers upgrade their networks to support higher speeds, they typically just need to upgrade the electronics at either end. The glass in the ground stays the same. This is why fiber is considered the infrastructure that will serve for decades.

Fiber is also inherently resistant to electromagnetic interference, which means it doesn't pick up noise from nearby electrical equipment, radio signals, or lightning strikes the way copper and coaxial cable can. This contributes to lower error rates and more consistent performance.

All of that sounds great, and it is. But here's where it gets more nuanced.

The two fundamentally different fiber products

When a provider says they offer "fiber internet," they could be talking about one of two very different things: shared fiber (often called best effort fiber or GPON/EPON) or dedicated fiber (often called DIA, which stands for Dedicated Internet Access). The difference between these two is as significant as the difference between cable and a private leased line.

Shared fiber, sometimes marketed as "fiber to the premises" or FTTP, uses a technology called GPON or EPON. In this setup, a single fiber strand from the provider's equipment is split, using a device called an optical splitter, to serve multiple customers. A typical split ratio is 1 to 32, meaning up to 32 customers share the capacity of a single fiber strand. The total capacity of that shared strand is usually around 2.5 Gbps download and 1.25 Gbps upload for GPON, or 10 Gbps symmetrical for the newer XGS-PON standard.

If those numbers sound huge, they are. But remember, that capacity is shared among up to 32 customers. At a 1 to 32 split ratio on standard GPON, the average available bandwidth per customer is about 78 Mbps download and 39 Mbps upload if everyone is using it simultaneously. In practice, not everyone uses the connection at the same time, so most customers experience speeds well above those averages most of the time. But the shared nature means that performance can vary, and the provider is typically overselling the capacity, banking on the fact that not everyone will need full speed simultaneously.

Sound familiar? It should. This is the same shared bandwidth model that cable internet uses. Shared fiber is better than cable in several important ways, including higher total capacity on the shared segment, better symmetry between upload and download, and the inherent reliability advantages of fiber over coaxial cable. But it's still shared. During peak usage, you may see reduced speeds and increased latency, just as with cable, though the effect is usually less severe because there's more total capacity to go around.

Dedicated fiber is a completely different product. A dedicated fiber connection gives you your own dedicated fiber strand that nobody else shares. If you're paying for 100 Mbps symmetrical dedicated fiber, you get exactly that, all the time. There's no split ratio, no contention, no peak hour degradation. The bandwidth is yours.

Dedicated fiber connections are what the industry means when they talk about "business grade" fiber, and they come with characteristics that shared connections don't: guaranteed bandwidth backed by a service level agreement, symmetrical speeds as standard (upload equals download), and typically much lower latency and jitter because there's no contention at any point in the last mile.

Why this distinction matters so much

The practical difference between shared and dedicated fiber shows up most clearly in consistency. A shared fiber connection might deliver 800 Mbps during off hours and 200 Mbps during peak, with jitter occasionally spiking during busy periods. Running a VoIP quality test at different times of day will reveal whether your fiber connection maintains the consistency that voice traffic needs. A dedicated fiber connection delivering 200 Mbps will deliver 200 Mbps at all times, with consistently low jitter and latency.

For web browsing and file transfers, the shared connection is arguably the better deal. You're getting higher peak speeds for less money. But for voice and video, the dedicated connection is in a different league. Remember, your phones don't need 800 Mbps. They need 1 to 2 Mbps with rock solid consistency. Our Bandwidth Calculator can help you figure out exactly how much capacity your office needs based on your call volume. The dedicated connection's lower speed number with guaranteed consistency is worth more for voice traffic than the shared connection's higher speed number with variable performance.

This is one of the areas where businesses get confused most often. They see a shared fiber plan offering a gigabit for $150 a month and a dedicated fiber plan offering 100 Mbps for $500 a month, and they can't understand why anyone would pay more for less speed. The answer is that they're buying two completely different products that happen to share the word "fiber" in their names.

How to tell which one you're being offered

Providers don't always make it easy to tell whether a fiber product is shared or dedicated. Here are some questions that will clarify things quickly:

Is the bandwidth symmetrical? If the plan shows different upload and download speeds, it's almost certainly shared. Dedicated fiber is symmetrical by default.

Does the plan come with an SLA that includes bandwidth guarantees, uptime guarantees, and credits for violations? Dedicated connections come with these. Shared connections typically don't, or they come with very weak ones.

What's the installation timeline? Shared fiber typically installs in days to a couple of weeks, similar to cable. Dedicated fiber can take 30 to 90 days or longer, because it often involves building or provisioning a new circuit specifically for your location.

What's the pricing structure? Shared fiber is priced like cable, usually under $200 a month for most plans. Dedicated fiber starts in the hundreds and can reach thousands per month depending on the bandwidth. If the pricing seems too good to be true for a "dedicated" connection, ask more questions.

Does the contract include a committed information rate (CIR)? This is the bandwidth the provider guarantees you will always have access to. Dedicated connections have a CIR equal to the speed you're paying for. Shared connections either don't have a CIR or have one that's much lower than the advertised speed.

Shared fiber is still really good

Don't walk away from this post thinking shared fiber is a bad product. It isn't. For most small and medium businesses, shared fiber, where available, is an excellent choice. It offers significantly better performance than cable, typically better upload speeds, better reliability, and it's priced competitively. Many businesses run VoIP over shared fiber without any issues.

The point is not that shared fiber is bad. The point is that it's not the same product as dedicated fiber, and understanding which one you need depends on your specific requirements. A five person office that makes a normal volume of phone calls will be perfectly well served by shared fiber. A 50 person office with heavy phone usage and mission critical cloud applications might need dedicated.

The availability gap

The biggest challenge with fiber of either kind is availability. Despite aggressive buildouts by major providers over the last several years, fiber is still not available at every business address. Availability varies dramatically by region, by neighborhood, and sometimes by building. The business next door might have fiber available while you don't, because the fiber passes their property but doesn't extend to yours.

Getting fiber to a location that doesn't currently have it can involve construction, which means permitting, trenching, and installation costs that are sometimes passed on to the customer. These construction costs can range from nothing (if the provider is building out the area anyway) to tens of thousands of dollars. This is another area where understanding your options and getting quotes from multiple providers matters a lot.

We'll cover the process of evaluating and comparing ISP quotes in detail in the Reading an ISP Quote post later in this series.

Next up: Dedicated Internet Access: What You're Actually Paying For, a deeper look at the premium product, who needs it, and who doesn't.