Cable modem
A cable modem is a device that transfers data, typically Internet services, generally over a cable television infrastructure. The term cable internet (or simply cable) refers to the overall system where an internet service provider (ISP) uses these devices. The modem part of a cable modem device transfers digital information over an analogue network. Many cable modems have additional advanced functions such as routing, virtual private networking and firewalling.
Cable modem for broadband internet
Cable modems have the primary function of bringing high-speed Internet access to consumers. They can take advantage of the existing high bandwidth available on the cable-television network that providers have rolled out to the majority of urban residences in many developed countries. Prior to the availability of such cabling systems, standard Internet access involved relatively slow dial-up access via the public switched telephone network.
Users in a single locality share the available bandwidth provided by the single coaxial cable in the neighborhood. Therefore, depending on the usage of the service (known as contention) Internet connection speeds can vary from blisteringly fast to very slow. Note however that uncertainty affects any measurements of internet speed, as bottlenecks can occur anywhere outside a user's or an ISP's control.
It should be noted that this shared cable is often seen as a weak point of Internet over cable. However, from a contention point of view it is just like any other network, including DSL services. If it is planned well a cable network can offer the same quality of service as a well planned DSL network. A DSL network can also have contention that makes it far worse than a cable network.
The real main weakness of cable networks using a shared line, especially considering the recent increase in hacking tools for DOCSIS cable modems, is the risk of loss of privacy a shared line may offer. Depending on the cable provider however, encryption may or may not be enabled on the cable network. So even that problem can be resolved.
Because of the high speeds offered, cable Internet, along with ADSL, has acquired the name broadband.
Cable modems most commonly use DOCSIS standard (Data Over Cable Service Interface Specification).
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See also
Cable modem manufacturers
External links