Hardware and Bit Rates
Broadband cable Internet access requires a cable modem at the customer's premises and a cable modem termination system at a cable operator facility, typically a cable television headend. The two are connected via coaxial cable or a Hybrid Fiber Coaxial (HFC) plant. While access networks are sometimes referred to as last-mile technologies, cable Internet systems can typically operate where the distance between the modem and the termination system is up to 100 miles (160 km). If the HFC network is large, the cable modem termination system can be grouped into hubs for efficient management.
Downstream, the direction toward the user, bit rates can be as much as 400Mbit/s for business connections, and 100Mbit/s for residential service in some countries. Upstream traffic, originating at the user, ranges from 384kbit/s to more than 20Mbit/s. One downstream channel can handle hundreds of cable modems. As the system grows, the cable modem termination system (CMTS) can be upgraded with more downstream and upstream ports, and grouped into hubs CMTS for efficient management.
Most Data Over Cable Service Interface Specification (DOCSIS) cable modems restrict upload and download rates, with customizable limits. These limits are set in configuration files which are downloaded to the modem using the Trivial File Transfer Protocol, when the modem first establishes a connection to the provider's equipment. Some users have attempted to override the bandwidth cap and gain access to the full bandwidth of the system (often as much as 30 Mbit/s), by uploading their own configuration file to the cable modem - a process called uncapping. Uncapping almost always a violation of the Terms of Service agreement.
Read more about this topic: Cable Internet Access
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