ADSL, SDSL, and G.lite
ADSL, SDSL, and G.lite.
xDSL, a term that encompasses the broad range of digital subscriber line (DSL) services, has the potential to revolutionize Internet access and telecommuting by offering a low-cost, high-speed data transport option for both individuals and businesses. xDSL provides data services more than 100 times faster than today’s top-speed, 56-kbps analog modems, using the local loop, the existing outside-plant telephone cable network that runs right to your home or office.
By last count, our Tech Support experts identified 16 distinct references to DSL services (including DSL itself), many of which prove to be redundant references to the same technology. Three popular types of xDSL are ADSL, SDSL, and G.lite.
ADSL (Asymmetric DSL) provides transmission speeds ranging from downstream/upstream rates of 9 Mbps/640 kbps over a relatively short distance to 1.544 Mbps/16 kbps as far away as 18,000 feet. The former speeds are more suited to a business, the latter more to the computing needs of a residential customer.
More bandwidth is usually required for downstream transmissions, such as receiving data from a host computer or downloading multimedia files. ADSL’s asymmetrical nature provides more than sufficient bandwidth for these applications.
The lopsided nature of ADSL is what makes it most likely to be used for high-speed Internet access. And the various speed/distance options available within this range are one more point in ADSL’s favor. Like most DSL services standardized by ANSI as T1.413, ADSL enables you to lease and pay for only the bandwidth you need.
SDSL (Symmetric DSL) represents the two-wire version of HDSL—which is actually symmetric DSL, albeit a four-wire version. According to Newton’s Telecom Dictionary, SDSL has also come to be known within the ANSI standards organization as HDSL2.
Essentially offering the same capabilities as HDSL, SDSL offers T1 rates (1.544 Mbps) at ranges up to 10,000 feet and is primarily designed for business applications.
G.lite, also known as ADSL lite, is a simplified xDSL offering standardized as G.992.2 by the ITU. Unlike some xDSL offerings, G.lite is the closest thing to plug-and-play DSL. Other DSL services require a truck roll—an on-site visit from telco service personnel to configure customer premises equipment, install a DSL modem and a splitter (which keeps the voice and data channels separate), and install an Ethernet card in the customer’s computer.
In theory, G.lite can eliminate the need for on-site installation by providing the customer with everything to set up the system themselves—no splitter is required.
Essentially consumer-grade DSL, G.lite is a direct response to the cable modem challenge. Initially driven by the Universal ADSL Working Group (UAWG), a consortium led by Microsoft®, Intel®, and Compaq® to standardize a mass-market version of DSL that could be implemented quickly and affordably, G.lite offers customers a variety of slower-speed DSL service levels to choose from to suit their particular system requirements.
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