Symmetric digital subscriber line

Definition
Symmetric Digital Subscriber Line (SDSL) can have two meanings:


 * In the wider sense, it is a collection of Internet access technologies based on DSL that offer symmetric bandwidth upstream and downstream. It is considered the opposite of asymmetric digital subscriber line (ADSL) technologies where the upstream bandwidth is lower than the downstream bandwidth.
 * In the narrow sense, SDSL is a particular DSL variant that supports data only on a single line and does not support analog calls.