What is Symmetric DSL?

Symmetric DSL, more commonly known as SDSL, is one kind of Digital Subscriber Line (DSL).

SDSL provides bandwidth between 72kb/s and 2,320kb/s.

Symmetric DSL is called "symmetrical" because the upstream and downstream connections have the same bandwidth.

SDSL requires only one pair of wired copper line to support a connection. These wires may reach as long as 3 kilometers.

Unlike Asymmetric DSL, Symmetric DSL uses the entire available bandwidth of the two copper wires. This means that regular analog telephone service through the PSTN is not possible over the same wires.

Symmetric DSL is a type of DSL technology which focuses on rate adaptation.

SDSL is usually more expensive than ADSL, but less expensive than a T1/E1 leased line. SDSL outperforms ADSL for dedicated data connections where upstream and downstream traffic is similar.

Symmetric DSL is slowly being replaced with G.SHDSL (Single-Pair High-speed Digital Subscriber Line).