Digital Subscriber Line
<communications, protocol> (DSL, or Digital Subscriber Loop, xDSL - see
below) A family of digital telecommunications protocols designed to allow high
speed data communication over the existing copper telephone lines between
end-users and telephone companies.
When two conventional modems are connected through the telephone system (PSTN),
it treats the communication the same as voice conversations. This has the
advantage that there is no investment required from the telephone company
(telco) but the disadvantage is that the bandwidth available for the
communication is the same as that available for voice conversations, usually 64
kb/s (DS0) at most. The twisted-pair copper cables into individual homes or
offices can usually carry significantly more than 64 kb/s but the telco needs to
handle the signal as digital rather than analog.
There are many implementation of the basic scheme, differing in the
communication protocol used and providing varying service levels. The throughput
of the communication can be anything from about 128 kb/s to over 8 Mb/s, the
communication can be either symmetric or asymmetric (i.e. the available
bandwidth may or may not be the same upstream and downstream). Equipment prices
and service fees also vary considerably.
The first technology based on DSL was ISDN, although ISDN is not often
recognised as such nowadays. Since then a large number of other protocols have
been developed, collectively referred to as xDSL, including HDSL, SDSL, ADSL,
and VDSL. As yet none of these have reached very wide deployment but wider
deployment is expected for 1998-1999.
2Wire DSL provider lookup.
["Data Cooks, But Will Vendors Get Burned?", "Supercomm Spotlight On ADSL" &
"Lucent Sells Paradine", Wilson & Carol, Inter@ctive Week Vol. 3 #13, p1 & 6,
June 24 1996].
Digital Simulation Language « Digital Simultaneous
Voice and Data « DIGITAL Standard MUMPS « Digital
» Digital Subscriber Line Access Module » Digital
Subscriber Loop » Digital Switched Network