What is Data Over Cable Service Interface Specification (DOCSIS)?

DOCSIS is a standard developed by CableLabs and other companies that allows cable TV providers to send and receive internet data over unused TV channels.

What is a data channel?

A data channel is a set amount of frequency used to upload or download data to and from a cable internet provider’s CMTS. Generally, cable modems support more downstream channels than upstream ones. The more downstream channels a modem supports, the more megabits you can download each second. For example, a modem listing 4×4 means it has an equal number of downstream and upstream channels. A 32×8 modem has 32 downstream channels but just 8 upstream ones. The DOCSIS version also applies in terms of speed. A 32×8 modem based on DOCSIS 3.0 has a maximum download speed of 1,400 Mbps while DOCSIS 3.1 enables 10,000 Mbps. Check out our guide on the best modems for gigabit internet if you want to replace your provider’s unit.

Can you use any modem with your internet connection?

No, you cannot use any modem. As described above, you can’t use a cable modem with a DSL connection, nor a DSL modem with a fiber connection. Your provider typically supplies the correct device for the internet type you have. You can purchase a modem if you want to avoid monthly fees, but it must be authorized by your internet provider. Spectrum, for example, provides a list of compatible modems that work with its three cable internet plans.8 We list the best cable modems for Xfinity, Spectrum, Cox, and more.

Home Networking Archives

What Is a Modem and Why You Need One to Get Internet

by Kevin Parrish | Sep 12, 2025 | Equipment Guides, FAQ, Home Networking

Find out what brings your internet connection into your home or office.

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Wi-Fi 7 Is the Best Yet, and Here’s Why

by Kevin Parrish | Aug 2, 2025 | Home Networking, Technology

Wi-Fi 7 is the latest standard for wireless connectivity. We dig in to see how it compares.

Testing Wi-Fi 7—Benchmarking the Fastest Wi-Fi Yet

by Kevin Parrish | Apr 18, 2025 | Home Networking, Technology

We ran several benchmarks to show how Wi-Fi 7 greatly improves upon Wi-Fi 6 and Wi-Fi 6E.

Are Ethernet Cables Slowing Your Connection?

by Kevin Parrish | Mar 7, 2025 | Home Networking

Wired connections are far more faster and reliable than wireless ones. But what if you experience unusually slow speeds with Ethernet? We walk you through a handful of steps to help get your Ethernet connections back up to blazing, glorious speeds.

Category: Home Networking