How Do Cable Companies Limit Your Internet Speed?

The same cable infrastructure that streams high-quality video content into homes can also provide some of the fastest Internet connections possible. The use of that infrastructure to provide Internet access has also allowed cable companies to compete in a market that was traditionally cornered by the telephone companies.

While cable Internet access is fast, there are several ways cable companies can and do limit connection speed. These need to be considered when choosing between cable Internet access and other options.

The modem provided by a cable Internet service provider (ISP) is configured to connect to the Internet at a certain speed. Typically as of 2010, it is configured to download at a speed of 500 kilobytes per second and to upload at a speed of 128 to 156 kbps. These settings can be programmed into the modem beforehand or downloaded to the modem directly from your ISP's servers upon first connection. The modem speed configurations are increased by your ISP when you purchase packages including more bandwidth and faster connection speeds.

While it is theoretically possible to uncap your modem's connection speeds, doing so will be detected by your service provider and is a punishable crime.

Cable companies can also limit Internet access speed by imposing what are known as speed caps. A speed cap can reduce 30 megabyte-per-second access, which is commonly marketed, to around 3 mbps. This is accomplished by monitoring the traffic flow in and out of a particular customer's home and throttling network speeds if the flow becomes too heavy.

Often, the customer will not notice the change. But on occasion such speed caps can have a heavy impact on Internet performance, making it difficult, if not impossible, to perform certain tasks. Speed caps are usually temporary and fluctuate depending on network traffic flow.

Why would cable companies want to limit Internet speeds when those incredible speeds are their main selling point? The ability to achieve unheard of download and upload speeds, cable Internet access is very attractive to those who would try to illegally run Web hosting services or other server-based activities from their homes. Even using home-based Web servers in a way that is not illegal can consume an enormous amount of network resources, making it difficult or impossible for others in the area to achieve reasonable Internet access.

If cable Internet access is popular in a certain neighborhood, many cable companies will slow cable modem service significantly if too many people in the area connect at the same time. This makes sense considering that Internet usage for many people includes a lot of streaming video and audio, which could disrupt cable television service.

While 30 to 100 mbps Internet access sounds like something wonderful, the truth is most people really don't need it. Even the highest-definition streaming video services can be used at much lower speeds. And the truth is that if too many people were actually connecting at those speeds, what is known as network packet loss would become a real problem. When data packets traveling the network are "lost," Internet performance suffers. And when traffic is flowing too heavy and too fast on the network, a lot of packets tend to get lost. By controlling Internet access speeds, cable companies ensure that packet loss remains minimal and thereby provide more-consistent service.