Digital Subscriber Line or Digital Subscriber Loop (DSL) is a type of high-speed Internet technology that enables transmission of digital data via the wires of a telephone network. DSL does not interfere with the telephone line; the same line can be used for Internet and regular telephone services. The download speed of DSL is normally in the range of 384 Kbps to 20 Mbps. The most popular implementation of DSL today is Asymmetric Digital Subscriber Line (ADSL).
DSL splits the frequencies used in a solitary phone-line into two main bands. The high-frequency band is used to send ISP data, and the low-frequency band is used to send voice data.
DSL setup
DSL service needs a DSL modem, otherwise known as a DSL Transceiver, to be connected to the phone line or jack. The DSL modem then connects to the computer. On the telephone company's end, the phone line is connected to a Digital Subscriber Line Access Multiplexer (DSLAM). DSLAM is basically a network apparatus that attaches multiple DSL lines to a high-speed Internet backbone by the means of multiplexing methods.
The DSL modem, DSLAM, and the computer must be in sync with each other for the DSL service to perform correctly. The sync process is as follows:
- When the DSL modem is turned on, it goes through a self-test.
- The DSL modem then checks its connection with the computer via the Ethernet or USB port.
- The DSL modem then tries to sync with the DSLAM.
The sync process usually takes place within a few seconds. DSL modems usually have a light indicator label marked as DSL or LINK. If the sync process is successful, the light indicator will remain lit with a green color.
DSL technologies
DSL technologies have evolved over a period of time, taking into consideration the constraints of distance between telephone exchanges and subscribers. Newer technologies such as VDSL and GDSL have immensely increased the data rate of DSL. The types of DSL technologies are as follows:
- ISDN Digital Subscriber Line (IDSL)
- High Data Rate Digital Subscriber Line (HDSL/HDSL2)
- Symmetric Digital Subscriber Line (SDSL/SHDSL)
- Symmetric High-speed Digital Subscriber Line (G.SHDSL)
- Asymmetric Digital Subscriber Line (ADSL)
- Asymmetric Digital Subscriber Line 2 (ADSL2)
- Asymmetric Digital Subscriber Line 2 Plus
- Asymmetric Digital Subscriber Line Plus Plus (ADSL++)
- Rate-Adaptive Digital Subscriber Line (RADSL)
- Very High Speed Digital Subscriber Line (VDSL)
- Very High Speed Digital Subscriber Line 2
- Etherloop (Ethernet Local Loop)
- Uni-DSL (Uni Digital Subscriber Line or UDSL)
- Gigabit Digital Subscriber Line (GDSL)
- Universal High bit rate Digital Subscriber Line (UHDSL)
