Symmetric or SingleDigital Subscriber Line (SDSL)

The goal of the DSL family was to continue to support and use the local cable plant. Therefore, providing high-speed communications on a single cable pair became paramount.

Most local loops already employ single cable pair today; thus, it is only natural to assume that providers would want this capability.

SDSL was developed to provide high-speed communications on that single cable pair, but at distances no greater than 10,000 feet.

Despite this distance limitation, SDSLwas designed to deliver 1.544 Mbps on the single cable pair.

Typically, however,the providers provision SDSL at 768 Kbps. This creates a dilemma for the carriers because HDSL can do the same things as SDSL.