 Digital Subscriber Line Access Multiplexer
Digital Subscriber Line (DSL) is a technology that brings high-bandwidth to homes and small businesses. A DSL circuit is swifter than a regular phone connection and the wires connecting the subscriber’s premises are the same copper wires as used for an ordinary phone connection. DSL offers data download rates up to 6 MBPS. The term xDSL refers to the different variations of DSL such as ADSL, HDSL, iDSL and RADSL. A Digital Subscriber Line Access Multiplexer (DSLAM) is a network mechanism located at a telephone company office that receives signals from multiple customer DSL connections with the combination of Asynchronous Transfer Mode (ATM), frame relay or IP networks.
With the help of DSLAM, a company can offer DSL with ATM, which is very fast, to homes and businesses. A DSLAM enables connections to many customers and integrates them into a single, high-capacity connection to the Internet. Generally, DSLAMs offer ease of use and can sustain multiple types of DSL in a single central office and different varieties of protocol and modulation – such as both CAP and DMT – in the same type of DSL. Additionally, DSL is capable of providing some more functions including routing or dynamic IP address assignment for the subscribers.
The DSLAM makes a distinction between service through ADSL and through cable-modems. Cable-modem users generally share a network circuit that passes through a neighbourhood, adding users. This may lead to a decrease in performance in many instances. ADSL provides a dedicated connection from each user back to the DSLAM, which indicates that the addition of new users does not result in a reduction in the performance – till the total number of users begins to saturate the single, high-speed connection to the Internet. At this juncture, an upgrade by the service provider can result in additional performance for all the users connected to the DSLAM.
DSL has been regarded as a data-oriented service by the telecom industry. The massive growth in Internet connections to homes and businesses has been the major reason for DSL’s deployment as a replacement for both dial-up modems and fractional T1 data services. Although voice and data traffic almost match each other in terms of bits transmitted, voice services command 90 per cent of telecom service. In this scenario, the transmission of telephone calls over a data network with xDSL as the access method is broadly anticipated to become a reality over the next few years. | 
01-05-2006, 08:08 AM
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