CABLE INTERNET ACCESS

    Cable Internet provides access using a cable modem on hybrid fiber coaxial wiring originally developed to carry television signals. Either fiber-optic or coaxial copper cable may connect a node to a customer's location at a connection known as a cable drop. In a cable modem termination system, all nodes for cable subscribers in a neighborhood connect to a cable company's central office, known as the "head end." The cable company then connects to the Internet using a variety of means – usually fiber optic cable or digital satellite and microwave transmissions.Like DSL, broadband cable provides a continuous connection with an ISP.

 Downstream, the direction toward the user, bit rates can be as much as for business connections, and 250 Mbit/s for residential service in some countries. Upstream traffic, originating at the user, ranges from 384 kbit/s to more than 20 Mbit/s. Broadband cable access tends to service fewer business customers because existing television cable networks tend to service residential buildings and commercial buildings do not always include wiring for coaxial cable networks. In addition, because broadband cable subscribers share the same local line, communications may be intercepted by neighboring subscribers. Cable networks regularly provide encryption schemes for data traveling to and from customers, but these schemes may be thwarted

Digital Subscriber Line (DSL) service provides a connection to the Internet through the telephone network. Unlike dial-up, can operate using a single phone line without preventing normal use of the telephone line for voice phone calls. DSL uses the high frequencies, while the low (audible) frequencies of the line are left free for regular telephone communication.These frequency bands are subsequently separated by filters installed at the customer's premises.

DSL originally stood for "digital subscriber loop". In telecommunications marketing, the term digital subscriber line is widely understood to mean Asymmetric Digital Subscriber Line (ADSL), the most commonly installed variety of DSL. The data throughput of consumer  services typically ranges from  to in the direction to the customer (downstream), depending on technology, line conditions, and service-level implementation. In  the data throughput in the upstream direction, (i.e. in the direction to the service provider) is lower than that in the downstream direction (i.e. to the customer), hence the designation of asymmetric. With a symmetric digital subscriber line the downstream and upstream data rates are equal

Very-high-bit-rate digital subscriber line  is a digital subscriber line  standard approved in 2001 that provides data rates up to  downstream and upstream over copper wires and up to 85 Mbit/s down- and upstream on coaxial cable.VDSL is capable of supporting applications such as high-definition television, as well as telephone services and general Internet access, over a single physical connection.

(ITU-T G.993.2) is a second-generation version and an enhancement of VDSL. Approved in February 2006, it is able to provide data rates exceeding 100 Mbit/s simultaneously in both the upstream and downstream directions. However, the maximum data rate is achieved at a range of about 300 meters and performance degrades as distance and loop attenuation increases.

By Alphonce Bhoke BAPRM 42527