DSL (Digital Subscriber Line)
Digital subscriber line (DSL, originally digital subscriber loop) is a
family of technologies that provide Internet access by transmitting
digital data over the wires of a local telephone network. In
telecommunications marketing, the term DSL is widely understood to mean
asymmetric digital subscriber line (ADSL), the most commonly installed
DSL technology. DSL service is delivered simultaneously with wired
telephone service on the same telephone line. This is possible because
DSL uses higher frequency bands for data. On the customer premises, a
DSL filter on each non-DSL outlet blocks any high frequency
interference, to enable simultaneous use of the voice and DSL services.
The bit rate of consumer DSL services typically ranges from 256 kbit/s
to over 100 Mbit/s in the direction to the customer (downstream),
depending on DSL technology, line conditions, and service-level
implementation. In ADSL, the data throughput in the upstream direction,
(the direction to the service provider) is lower, hence the designation
of asymmetric service. In symmetric digital subscriber line (SDSL)
services, the downstream and upstream data rates are equal.
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