Forget about Fiber vs. Cable: Xfinity’s HFC vs. Fiber Tells a Whole New Story

The days of “traditional” cable internet are gone. Nearly all internet providers that were once associated with that term have upgraded to hybrid network designs.

Hybrid fiber-coaxial (HFC) is a network architecture that uses fiber optic cables from the provider’s facility to the neighborhood nodes, then coaxial cables for the final connection to the homes and businesses. Xfinity uses an HFC network, which combines fiber optic infrastructure with coaxial cables for the last-mile delivery—making it neither traditional cable nor pure fiber, but a hybrid of both.

What kind of internet setups exist for homes and businesses?

Fiber to the node (FTTN) is a wide-area network design that combines fiber optic cables with older copper wiring used for telephone service.

The connection begins at an internet provider’s master facility (called a headend or central office). From there, fiber lines connect it to a distribution box called a node.

From the node, the network uses existing telephone lines to transmit data to and from a DSL modem located in a home or building.

Xfinity and other “cable internet” providers use something similar

Internet providers like Xfinity use a related architecture called hybrid fiber-coaxial (HFC). Instead of telephone wires, HFC uses coaxial cables from the node to the cable modem located in the home or building. It also uses amplifiers every few thousand feet to maintain signal strength.

For residential internet, one HFC node typically feeds a specific neighborhood zone, though larger communities are split across multiple nodes depending on the number of homes served.

FTTN is different than FTTH and FTTP

Fiber to the home (FTTH) and fiber to the premises (FTTP) mean the same thing: The connection from the provider all the way to the building is fiber cabling. FTTH usually refers to residential setups, while FTTP is a broader term that includes businesses and government facilities. Fiber does not run inside most buildings.

Fiber to the curb (FTTC) is a middle-ground design. It brings the fiber line to a small box or pole right on the street near a small cluster of homes. This drastically shortens the final telephone line or coaxial journey without the high cost of rewiring the internal and external setups of every building.

FTTD brings fiber all the way to the device

Fiber to the desk (FTTD) sees fiber installed all the way to the customer’s device, such as a workstation, a thin client, or a network switch. It’s a different scenario than FTTH and FTTP setups where fiber lines stop at the fiber “modem” (the Optical Network Terminal, or ONT) used to translate optical signals into Ethernet ones.

FTTD designs typically reside in business districts, not in residential areas.

Why don’t HFC internet providers switch to 100% fiber?

HFC internet providers normally don’t overhaul telephone and coax-based networks to provide FTTH service due to cost.

Replacing existing networks requires:

• Removing miles and miles of telephone or coax lines
• Removing amplifiers for coax networks
• Trenching in public areas to bury fiber lines
• Trenching and installing fiber lines on private property
• Installing fiber receivers in buildings

For example, imagine the number of neighborhoods and business districts in one city, then zoom out to see the number on a county level, on a state level, and finally nationwide. The cost could be billions in manual labor alone. Add the hardware investment, and it’s easy to see why HFC providers choose to update existing networks instead.

However, HFC internet providers generally use 100% fiber networks when building networks in new neighborhoods and business districts. It makes no sense to invest in old technology that costs more to maintain than a passive all-fiber network.

According to Xfinity, it connected over 65 million homes and businesses as of June 2026. So, for example, if 60 million homes needed a switch from coaxial to fiber, and the cost of each home would be roughly $1,500, the cost would be $90 billion. A $90 billion network rebuild would be an extraordinary investment for a single division of any company. Shareholders would have a hard time justifying that kind of expenditure when the existing coax network can be upgraded for a fraction of the cost.

How HFC internet providers are competing with residential fiber internet

The buzz around fiber internet is hot. Fiber internet providers and third-party sites often say fiber internet is faster than cable internet.

However, here’s the real story: Data travels at roughly 66.67% to 70% of the speed of light through both copper and glass. The real difference in the two internet types is how much bandwidth the network can allocate to each customer.

Coaxial networks were originally designed for TV

The origin of coax networking isn’t anything new, so we won’t dive into that explanation. But once cable TV operators began to offer internet, the bandwidth wasn’t divided equally due to hardware limitations. Plus, users simply did not need large amounts of upload bandwidth in the early days of cable internet, so offering symmetrical speeds would have been a waste of bandwidth.

In 2026, the asymmetrical allocation model still exists in HFC network setups, but the upload demand is now larger thanks to cloud backups, online gaming, video conferencing, and more. Residential fiber networks have generally been designed around a much larger upstream capacity than traditional cable networks, making symmetrical service a common offering.

That said, a 1Gbps fiber internet plan is no faster than a 1Gbps plan offered by an HFC internet provider like Xfinity when it comes to downstream throughput. The difference is in the upload bandwidth allocation, where the fiber plan may offer 1Gbps while the coax-based plan may be limited to 50Mbps. The signal travels through both mediums at roughly similar speeds—the only difference is that fiber networks generally have more usable bandwidth available for customers, which translates into higher observable speeds.

Bandwidth is the maximum amount of data a connection can deliver in a single second. Speed is the observable rate at which data is delivered to the customer. But consider, what do you need for your internet activities?

HFC providers are now upgrading their fiber-coax networks

In order to better explain how HFC internet providers are upgrading their existing networks to compete with residential fiber internet, let’s take a look at the typical Passive Optical Network (PON) used to deliver internet to residents.

Typical fiber internet topology

Headend/OLT  >  fiber line  >  passive splitters  >  fiber line >  ONT

The Optical Line Terminal (OLT) typically resides in the central office and sits between the provider’s internal Ethernet-based network and the wide-area network connecting customers to the internet. Signals pass through miles of fiber lines and unpowered splitters until they reach Optical Network Terminals (ONTs) in buildings.

Some internet providers call ONTs “fiber modems” for simplicity’s sake, but the term isn’t technically precise. An ONT converts optical signals into electrical Ethernet signals and performs additional functions required to communicate over the provider’s fiber network.

ONTs are typically installed on walls, although some internet providers supply a gateway that combines the ONT with a Wi-Fi router.

Now, let’s look at the typical HFC network layout.

Typical HFC internet topology

Headend/CMTS  >  fiber line >  optical node  >  coaxial line >  amplifiers/taps  >  cable modem

The Cable Modem Termination System (CMTS) also resides in the central office. But unlike the OLT, which manages the PON connection to ONTs, the CMTS manages DOCSIS communications with cable modems.

Once the optical signal reaches a node, it’s converted to an RF signal and delivered over coax. Powered amplifiers along the route keep the signal strong until it’s received and processed by the customer’s cable modem. From there, the data is converted into Ethernet signals and passed on to the next wired device—typically the router.

Coax-based gateways combine the cable modem with a Wi-Fi router, so the RF signal is converted and retransmitted over Wi-Fi, or converted to Ethernet signals for wired transmissions.

DOCSIS 4.0 enables more upstream bandwidth

The latest DOCSIS specification expands the amount of spectrum available for data transmission over coax.

DOCSIS 4.0 supports two different methods: Extended Spectrum DOCSIS (ESD) and Full Duplex DOCSIS (FDX).

With ESD, upstream and downstream traffic occupy separate frequency ranges. Here are the ranges and their theoretical maximum throughput:

Technically, an HFC provider using ESD could offer symmetrical service up to 6Gbps.

However, some providers, including Xfinity, aren’t taking that approach. Instead, they’re investing in DOCSIS 4.0 Full Duplex (FDX).

Full Duplex is the key to true symmetrical speeds over coax

Unlike ESD, FDX allows the network to reuse the same frequencies in both directions. Interference cancellation techniques are used to separate the downstream and upstream signals. This approach increases the amount of data the coaxial network can carry without requiring an equivalent amount of spectrum to be dedicated to upstream traffic.

According to Harmonic, its Unified DOCSIS 4.0 platform demonstrated peak symmetrical speeds of 9Gbps using a shared spectrum of 108–684 MHz (576 MHz total). Because the same spectrum can be used in both directions, the network can make more efficient use of available capacity as upstream and downstream demand changes.

In theory, the shared spectrum can carry large amounts of upstream and downstream traffic simultaneously. However, the typical customer rarely uses their full download and upload capacity at the same time.

Home and field equipment need a DOCSIS 4.0 upgrade

Switching to DOCSIS 4.0 isn’t something that HFC providers simply switch on. In addition to upgrading equipment in the central facility, providers must upgrade equipment installed in the field. This swap-out includes all the nodes and amplifiers managed by the provider, and all the modems distributed to homes and businesses. The new equipment includes:

• CommScope STARLINE FDX amplifiers
• OM6000 FDX nodes
• Cable modems and gateways with the Unified DOCSIS 4.0 chipset

The thing to keep in mind is that the new FDX-based design changes where signal processing takes place. Previously, much of the DOCSIS processing was performed in the central facility. But with FDX, some of that processing moves to the node, which generates the RF signal for transmission over coax. Harmonic’s cOS platform provides the virtualized DOCSIS functions that work with this network design.

Other upgrades to improve performance

Increasing the spectrum and employing Full Duplex transmissions isn’t enough. Other technologies need to be in place to improve performance and reduce latency.

Quilt’s Open Edge Content Delivery Network (CDN)

Quilt’s Open Edge platform allows internet providers to place content caches within their own networks, bringing frequently requested content closer to users. This setup improves content-delivery performance and reduces network congestion caused by repeatedly pulling content through the core network.

NVIDIA GPU Processing

Xfinity is also testing NVIDIA GPUs at the edge of its network. Rather than sending AI workloads to distant data centers, Xfinity is placing GPU-powered computing in regional facilities closer to customers. The goal is to reduce the round-trip time required for AI “thinking” and enable new low-latency applications such as AI assistants and cloud gaming.

According to parent company Comcast, its network has hundreds of hub sites that could eventually support this type of edge computing.

Artificial intelligence

AI embedded in amplifiers enables self-monitoring, self-healing, and self-maintenance. Paired with the Janus initiative, AI can scale capacity where needed, reroute traffic around damaged equipment, and more.

HFC networks will support 25Gbps

The current issue with HFC providers is that fiber internet has the upper hand in download speed and symmetrical speeds. HFC providers like Xfinity do install 100% fiber networks in new markets, so the competition they face from rival fiber internet providers applies primarily to their existing coaxial-based networks.

The fastest home fiber internet plan we have in our database is 50Gbps, which is ludicrous for home use and requires special hardware to use. The second-fastest plan for home fiber internet is 8Gbps, followed by 2Gbps with coaxial-based internet. So clearly, customers know where to go if they want the most bandwidth available: fiber internet.

However, DOCSIS 4.0 changes the equation. Using the split spectrum method, HFC providers can theoretically achieve up to 6Gbps upstream and 10Gbps downstream—up to 6Gbps symmetrically. The combined spectrum method allows upstream and downstream traffic to use the same spectrum simultaneously. Harmonic and Comcast have demonstrated 9Gbps symmetrical speeds using this approach.

That said, a 9Gbps fiber-powered HFC plan can compete directly with a 9Gbps 100% fiber plan when it comes to advertised bandwidth.

But the upgrades don’t stop there. Comcast, Charter, and Broadcom are developing Unified DOCSIS technology intended to extend HFC spectrum to as much as 3 GHz. It sets the stage for speeds of 25Gbps and beyond over existing HFC networks.

Does this mean Xfinity and other HFC providers will need to rip out what they just installed and replace it with newer equipment? Yes. Some equipment will eventually need to be replaced—nodes, amplifiers, and modems, among others. Again.

Isn’t continuously swapping out components in a coax-based network more expensive than ripping it all down and installing 100% fiber networks? No, because HFC providers can keep portions of their networks in place, including all the lines and customer drops.

Forget fiber: Xfinity’s HFC network is a fierce competitor

Xfinity operates both 100% fiber and HFC networks. On its HFC network, fiber extends from the central facility to neighborhood nodes, while coax completes the connection to homes and businesses.

And while Xfinity’s coaxial-based service currently doesn’t go beyond 2Gbps in download speed, that will change in the near future. As Xfinity and Harmonic have demonstrated, 9Gbps symmetrical speeds are possible, followed by the potential for 25Gbps service as the network evolves toward a wider spectrum.

Still, the average household doesn’t need anything close to 9Gbps or 25Gbps of internet throughput today. Multi-gigabit internet becomes more useful as devices support faster wireless speeds, which translates to faster data rates at long range. It can also benefit whole-home mesh systems by providing more capacity for wireless backhauls, helping maintain faster speeds in areas that previously had lower throughput.

So, while some may boast that fiber internet is faster and more reliable than cable internet, our annual numbers tell a different story and likely reflect all the work Xfinity has invested in its hybrid fiber-coax networks. It has the third-highest average speed in 2026, falling behind GFiber and T-Mobile Fiber, while its reliability score closely matches its fiber internet rivals.

Ultimately, don’t buy into all the fiber hype powered by assumptions. Yes, the internet backbone is built on fiber, but that doesn’t mean every residential and business internet connection is built the same way.

As we’ve shown here, Xfinity and other HFC providers are continuing to push the technology forward, delivering speeds and reliability that can be comparable to fiber. Customers don’t necessarily need to wait around for fiber to reach their neighborhood or business when an existing HFC provider may already deliver the performance they need.

Xfinity Internet plans

FAQ about HFC vs. fiber

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