Cable Modem Definition | The Interactive Glossary

Cable modems provide a continuous connection to the Internet and, depending on the modem’s make and your Internet plan, are capable of transmitting data at speeds up to several hundred Mbps.

Cable modems vary considerably in terms of performance and functionality. Older modems will likely not be able to handle modern Internet speeds, particularly more expensive plans; while top of the line modems may be far more than you need for a low-price or even mid-range Internet plan. Some modems include a built-in wireless router, so you can easily connect all your devices to the Internet without needing any additional equipment. Other modems must be wired to a router in order to share your connection with more than one device.

Frequently Asked Questions

How do I choose the best modem?

The best modem for your household will depend on the service you subscribe to. If your cable company offers 100 Mbps plans, you won’t be able to take advantage of that without a high-speed, DOCSIS 3.0 modem. However, if you’re only subscribing to a 20 Mbps or lower plan, an older DOCSIS 2.0 modem may work just fine. Before you go out and purchase a modem, check with your local cable provider. Their website should provide a list of approved modems for each level of service. If not, give them a call. Most cable providers also offer a rental option. While this will likely be more expensive in the long run to purchasing your own, it means you will always get a new modem when you need it.

What is DOCSIS?

DOCSIS stands for Data Over Cable Service Interface Specifications. It is the standard specifications used by all cable modems to transmit and receive data between your cable provider and your home or business. First developed in 1997, there have been several versions of DOCSIS over the years, each adding additional capabilities and speed. DOCSIS 3.1 was released in 2013 and capable of downloads speeds of 10 Gigabits per second and upload speeds of 1 Gbps, but as of the time of this writing, most current modems still support DOCSIS 3.0. With max download speeds ranging from 320 Mbps to 680 Mbps, and upload speeds around 120 Mbps, these modems are still capable of significantly faster speeds than any cable company is providing…but hopefully by the time you read this, all that will have changed!

Why are upload speeds so much lower?

Most Internet Service Providers offer plans with significantly higher download speeds compared to upload speeds. This is because most consumers require far less in terms of upload capabilities. When we upload photos or even videos to our favorite social media site, we expect it to go quickly, but not instantly. On the other hand, when we stream movies or music, we insist on the download happening fast enough that we can watch the movie or listen to the song uninterrupted.