When it comes to land-based broadband connections, there are currently two competing technologies: Cable vs Fiber-optic, or Fiber, for short.
This post will explain the two briefly and give some suggestions on how to handle each.
By the way, if you live in areas with both options, you can use them together. All you need is a router that features Dual-WAN, plus two broadband connections (preferably of similar speeds), but that’s probably a topic of another post.
With that, let’s find out the differences between Cable vs Fiber.
Dong’s note: Part of this post was initially published as the introduction in the piece on how to replace the ISP-supplied equipment with your own. I moved it out on December 28, 2021, to further clarify the topic.
Cable vs Fiber-optic, or modem vs ONT
Before continuing, though, let’s address the elephant in the room: your beloved DSL. Yes, I’m aware of it.
Short for digital subscriber line, DSL uses the existing phone line — that same wire we once used for the good old Dial-up connection — to deliver modest broadband connections.
DSL has been significantly declining due to slow speeds and unreliability in the past couple of years. Most DSL providers have been slowly moving to Fiber as the replacement.
But in a way, as far as the Internet net is concerned, DSL is similar to Cable.
As the name suggests, Cable Internet is the broadband connection via the coaxial copper wires used originally for Television or Cable TV.
Since the wiring was made initially for a different purpose, there needs to be a modem to make it work for the Internet, like the case of DSL.
A modem is a device that works both as a modulator and a demodulator. It converts service signals into computer data signals and vice versa. Since the service in question here is the cable TV, we have ourselves the Cable modem.
To carry data signals, Cable modems use a standard called DOCSIS, which is an acronym for data over cable service interface specifications. That’s about the only acronym you need to know in the world of Cable Internet.
DOCSIS helps make broadband affordable since it leverages the existing copper wiring for cable TV — the infrastructure is already there.
The biggest shortcoming of DOCSIS is that it has lopsided connection speeds — the upload tends to be one-tenth (or even lower) the download, or asynchronous Internet. That’s the case with all cable connections, including mine.
The curious case of Cable Internet’s fast download vs slow upload speeds
In case you’re wondering why Cable Internet’s upload speed is always much slower than download, the reason is quite simple.
Originally, the network of coaxial copper wires was built to deliver a ton of data — the video and audio signals of Cable TV — to each household without the need to get anything in return. For the most part, TV viewers don’t send anything back to the provider.
When provisioned to deliver data, the same concept applies to the wiring, but this time that’s because the provider can lower the investment and maintenance costs by not providing fast upload speed. So only lopsided modems are manufactured, and the rest is history.
And that has generally worked out fine since, in practice, consumers receive much more data (download) than they send (upload).
(Come to think about it. We tend to consume more than we give back, which says a lot about us as a species.)
There are two main versions of DOCSIS in use, including DOCSIS 3.0 and DOCSIS 3.1. Consequently, picking a suitable modem can be quite a task. It’s so much so that it needs a different section entirely — more below after we’re done with Fiber.
Fiber-optic has a ton of confusing terms.
Technically, the name is GPON, short for Gigabit passive optical networks. GPON itself is part of the Fiber to the Premises (FTTP), a.k.a Fiber to the Homes (FTTH), broadband delivery approach.
Nowadays, it’s more often called PON since it can deliver Multi-Gig broadband.
Since the wiring is designed for data connections in mind, Fiber doesn’t require a modem. Instead, it uses an ONT, short for Optical Network Terminal, at each endpoint.
In other words, an ONT is the Internet outlet that links to an Internet service provider (ISP) to deliver Internet to a home or an office. Each ONT has a network port to connect to a router’s WAN port.
Though totally different in technologies, an ONT to a Fiber-optic service is similar to a modem to a Cable Internet plan.
A modem converts the signals between those of the service line and data. An ONT sends infrared light pulses to the ISP’s server to send and receive data.
Both get you connected at high speeds. How high? That depends on the Internet plan you have.
The messy acronyms aside, Fiber-optic gives you “high-quality” Internet thanks to the fact that the modern optical data line runs (almost) directly from the provider to your home.
Among other things, this type of broadband delivers high speeds in both directions (upload and download) — that’s synchronous Internet — currently up to 10Gbps and even faster.
On the downside, Fiber is expensive — it requires new wiring — and generally has a single point of failure. If a line is cut or broken, the Internet can be down for a large population.
Cable vs Fiber: The future is in the latter
Generally, Fiber is the way of the future. It’s clean, fast, versatile, and built purposely for a high-speed data network. It’s simply far superior to the old copper wiring of Cable.
On top of that, with TV services moving slowly to streaming, there’s no longer a need for new coaxial development.
Cable Internet is just a matter of leveraging existing infrastructure until it’s no longer suitable or worth the maintenance, which is still far in the future.
That said, Fiber is the only wiring needed and the preferred one for new real-estate and technology developments. In other words, if your area doesn’t have Cable or Fiber right now, it’ll get the latter, if at all.
Notes on getting Fiber-optic hardware
When you order Fiber Internet, you’ll get an ONT — your provider will install one in your home.
The ONT might come as a standalone unit, like one in the picture you see above, or a combo device that is a Wi-Fi router with a built-in ONT.
For flexibility, it’s always best to get just a standalone ONT when possible. That gives you the freedom to get a Wi-Fi solution of your choosing.
If you get a combo device, just like the case of a Cable gateway, you will likely have to do some tweaking to avoid double NAT.
And that’s the only thing you need to keep in mind when getting Fiber. On the other hand, getting a Cable modem can be pretty complicated.
Cable modem (further) explained: DOCSIS 3.0 vs DOCSIS 3.1
Again, currently, the world uses versions 3.0 and 3.1 of the DOCSIS standard. (There’s no need to worry about the earlier revisions — thank goodness!)
DOCSIS’s specifications can be very confusing. For one, it changes depending on the region. For example, a set of particular modem specs might mean different speeds in the US than they do in the EU.
Also, it involves many technicalities, like channels, streams, QAM, etc. I’m not getting into the details here, nor should you care about them. Instead, let’s focus on the two standards and what they mean.
DOCSIS 3.0: Stream channels matter
In a simplified way, with DOCSIS 3.0, you can grade a cable modem’s speeds via the number of stream channels it can handle.
There are downstream channels (for download) and upstream channels (for upload). More stream channels, or channels for short, translate into faster speeds.
Each modem comes with an indicator of the number of channels it can handle via a pair of digits. For example, the Netgear CM600 is a 24×8 modem. It has 24 downstream channels and 8 upstream channels.
In the US, the DOCSIS 3.0 standard delivers about 40Mbps per channel for download and 4Mbps for upload — again, these are ballpark numbers that vary from one provider to another. As a result, the CM600 caps at 960Mbps download and 32Mbps upload.
Generally, DOCSIS 3.0’s number of channels max out at 32×8. So a top-notch modem of this standard has cap speeds of some 1.3Gbps download. And that’s DOCSIS 3.0’s maximum bandwidth.
It’s important to note that just because a modem supports a specific performance grade (represented by the number of stream channels) doesn’t mean it will work at that grade. That depends on the service provider’s end (and the Internet plan you pay for).
And a provider generally loves to use as few channels as possible. The more stream channels, the more expensive equipment they need.
And that brings us to DOCSIS 3.1. This standard delivers a higher speed per stream channel. This version needs fewer channels to provide the same bandwidth and now has the cap of some 10Gbps in theory — that’s some 10x of version 3.0.
DOCSIS 3.1: Top-tier DOCSIS 3.0 is the base
Though the actual speed varies from one vendor to another, a low-end DOCSIS 3.1 modem can generally deliver at least the same download speed as a top-tier 32×8 DOCSIS 3.0 counterpart.
DOCSIS 3.1 is so fast that vendors now omit the stream channel numbers. Instead, they call the modem DOCSIS 3.1 and its cap speed, Gigabit or Multi-Gig. The Netgear CM2000, for example, is a DOCSIS 3.1 2.5Gbps modem.
In other words, the stream channel numbers, such as 32×8 or 24×8, are only relevant in DOCSIS 3.0, where most modems cannot deliver Gigabit Internet. Starting with 3.1, Gigabit is the minimum, and Multi-Gig is a new norm.
Or you can safely assume that DOCSIS 3.1 starts at the place where DOCSIS 3.0 maxes out. And generally, most, if not all, DOCSIS 3.1 modems can function as 32×8 DOCSIS 3.0 ones. But it’s ultimately the Internet provider that decides which modem works and at what speed.
(DOCSIS 3.1 includes other benefits, but they are generally irrelevant from the consumers’ end.)
Real-world cable (download) speeds
No matter how fast a cable modem’s advertised speed is, its actual ceiling speed is always its LAN port — the one you connect to a router’s WAN port.
That said, all cable modems with a Gigabit LAN port will cap at 1Gbps or lower.
Some modems can deliver Multi-Gig broadband speeds. In this case, they must have a Multi-Gig port (be it 2.5Gbps, 5Gbps, or 10Gbps) or features WAN Link Aggregation where you can combine two 1Gbps ports into a single 2Gbps WAN connection.
And, of course, to enjoy Multi-Gig broadband, you need to have a router supporting similar speed grades on the WAN side. After that, the speed must be available from the provider’s end. And, finally, you’re willing to pay for it.
The point is, there’s no need to get a modem that can deliver a faster speed than your current subscription. However, it never hurts to have a top-tier modem if you want to upgrade your broadband later.
DOSIS3.0 vs DOCSIS 3.1: Which to get
First of all, again, when applicable, you should get just the modem itself instead of a combo device which is a Wi-Fi router with a Cable modem built-in.
(The former gives you the flexibility in handling the hardware — you’re not stuck with a combo that’s lacking in either the modem or the Wi-Fi portion or both.)
If you have a sub-Gigabit Cable Internet plan, in most cases, it doesn’t matter which modem you get.
However, keep in mind that if your broadband is slower than 300Mbps, it might require a DOCSIS 3.0 modem. So check with your provider.
On the other hand, with a Gig+ and Multi-Gig Internet plan, DOCSIS 3.1 is a must. On top of that, you might want to get a cable that supports Link Aggregation if that’s how your provider delivers Multi-Gig.
Here’s my simple rule to determine which type of modem to get based on your Internet download speed:
- 500Mbps or slower: Get a DOCSIS 3.0 modem. A DOCSIS 3.1 one is not necessary and might not work.
- 500Mbps to sub-Gigabit: Either will do, but it’s a better idea to go with DOCSIS 3.1.
- Gigabit for faster (Gig+, Multi-Gig): DOCSIS 3.1.
Both Cable Internet and Fiber will be able to give you faster broadband than any current application would ever need, providing you don’t mind paying.
But in more ways than one, Fiber is the way of the future. It has a much higher ceiling speed, especially upload speed, and might be the only choice for many regions.
In the meantime, those with an existing Cable TV network can benefit from the evolution of coaxial copper wiring. This infrastructure is still more than enough for anyone’s broadband needs for the foreseeable future.
No matter which you opt for, make sure you get just the terminal device (modem or ONT) and not a gateway — that’s a combo device that has a Wi-Fi router and the modem/ONT built-in — when possible.