Cable Internet

Cable Internet

In telecommunications, cable Internet is a form of broadband Internet access that uses the cable television infrastructure. Like digital subscriber lines and fiber optic networks, cable Internet bridges the last kilometre or mile from the Internet provider to the subscriber. It is layered on top of the existing cable television network infrastructure; just as DSL uses the existing telephone network. Cable networks and telephone networks are the two predominant forms of residential Internet access. Recently, both have seen increased competition from fiber deployments, wireless, and mobile networks.

Hardware and bit rates

Downstream, which goes toward the user, bit rates can be as much 50 megabits per second for business connections, and two to twenty megabits for consumers depending on the country. Upstream, which goes from the user rates range from 384Kbit/s to more than 20Mbit/s.

Broadband cable Internet access requires a cable modem at the customer premises and a CMTS (Cable Modem Termination System) at a cable operator facility (typically a headend or hub location). The two are connected via coaxial cable or, more commonly, a Hybrid Fiber Coaxial plant. While access networks are sometimes referred to as "last-mile" (or "first-mile") technologies, cable Internet systems can typically operate where the distance between the modem and CMTS is up to convert|100|mi|km.

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 uploaded to the modem using the Trivial File Transfer Protocol, when the modem first establishes a connection to the provider's equipment.Fact|date=April 2008

Criticism

Like all residential broadband technologies, such as DSL, FTTX, Satellite Internet, or WiMAX, a population of users share a fixed channel capacity. Some share only their core network, while some including Cable Internet share also share the access network. Users in a particular neighborhood may share only a single coaxial cable line. So, the service can become sluggish if many people are using the service at the same time. This arrangement allows the network operator to take advantage of statistical multiplexing, a bandwidth sharing technique which is employed to distribute bandwidth fairly, in order to provide an adequate level of service at an acceptable price. However, the operator has to monitor usage patterns and scale the network appropriately, to ensure that customers receive adequate service even during peak-usage times. Some operators, such as Virgin Media in the UK, use a bandwidth cap, or other bandwidth throttling technique. In the case of Virgin Media, the user's download speed is limited during peak times, if they have downloaded a large amount of data that day.cite web | last =WHO | authorlink =PC Pro | title =Virgin Media cuts broadband speeds for the heavy downloaders |date=May 2007 | url =http://www.pcpro.co.uk/news/112273/virgin-media-cuts-broadband-speeds-for-heavy-downloaders.html]

Many cable Internet providers offer Internet access without tying it to a cable television subscription. This is achieved by charging higher rates than if one bundles it with a cable television subscription. The extra cost is to cover the cable line access, much like phone companies charge a small line access fee for having DSL Internet service without a phone subscription (naked DSL). The cable line tap outside the residence is adjusted to prevent analog cable television channels from being transmitted through. The customer does not receive any cable television channels, including the basic channels. Internet Service Providers who resell high-speed Internet access from or through cable companies, such as Earthlink and AOL, are generally not subject to these higher rates. They can as well provide you Internet service without a cable television subscription. However, it is likely that the bill will be sent by the cable company on behalf of the Internet Service Provider.

One downstream channel can handle hundreds of cable modems. As the system grows, the CMTS can be upgraded with more downstream and upstream ports. If the HFC network is vast, the CMTS can be grouped into hubs for efficient management. Some usersFact|date=April 2008 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 is almost always a violation of the Terms of Service agreement.Fact|date=February 2007

See also

* List of cable Internet providers
* Cable modem

References


Wikimedia Foundation. 2010.

Игры ⚽ Нужна курсовая?

Look at other dictionaries:

  • cable internet — noun Internet connectivity received through coaxial cables, usually via the same medium as cable television …   Wiktionary

  • List of cable Internet providers — North America Canada Canadian cable operators offer varying levels of service based on different price points, though the actual marketing terms vary. Services offered by the major Canadian providers are included below. In 2007 Telenet bought UPC …   Wikipedia

  • Aurora Cable Internet — Infobox Company company name = Aurora Cable Internet company type = Public foundation = Aurora (1999) location = Aurora, Ontario key people = industry = Communications Services products = Cable TV, Internet, Telecommunications revenue = num… …   Wikipedia

  • Internet por Cable — Saltar a navegación, búsqueda En las telecomunicaciones, el Internet por cable es un tipo de acceso de banda ancha al Internet. Acceso al Internet por Cable El término acceso al Internet por cable o Cable Internet se refiere al uso de la… …   Wikipedia Español

  • Cable modem termination system — Cable modem terminations system A cable modem termination system or CMTS is a piece of equipment typically located in a cable company s headend or hubsite, and used to provide high speed data services, such as cable Internet or voice over… …   Wikipedia

  • Internet in Australia — Internet access was first available in Australia to universities via AARNet in 1989. The first commercial dial up ISPs (Internet Service Providers) appeared in capital cities soon after and by the mid 1990s almost the entire country had a wide… …   Wikipedia

  • Cable television — CATV redirects here. For CAT5 cable, see Category 5 cable. Coaxial cable is often used to transmit cable television into a residence. Cable television is a system of providing television programs to consumers via radio frequency (RF) signals… …   Wikipedia

  • Cable modem — Motorola SurfBoard SBV6120E EuroDOCSIS 3.0 cable modem A cable modem is a type of network bridge and modem that provides bi directional data communication via radio frequency channels on a HFC and RFoG infrastructure. Cable modems are primarily… …   Wikipedia

  • Cable Box — Numericable Logo de Numericable Dates clés 1985 : création par le groupe Lyonnaise des eaux de la société « Paris Câble » 1996 : Création du groupe Lyonnaise Communications …   Wikipédia en Français

  • Internet in Colombia — Colombia is still far behind Brazil, Mexico, and Argentina in terms of online usage. [http://lcweb2.loc.gov/frd/cs/profiles/Colombia.pdf Colombia country profile] . Library of Congress Federal Research Division (February 2007). This article… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”