Symmetric Digital Subscriber Line Symmetric Digital Subscriber Line ( SDSL ) is a Digital Subscriber Line ( DSL ) variant with E1 -like data rates ( 72 to 2320 kbit/s ) . It runs over one pair of copper wires , with a maximum range of about 3 kilometers . The main difference between ADSL and SDSL is that SDSL has the same upstream data transfer rate as downstream ( symmetrical ) , whereas ADSL always has smaller upstream bandwidth ( asymmetrical ) . It is quite expensive . SDSL was never properly standardised until Recommendation G.991.2 ( ex-G.shdsl ) was approved by ITU-T . SDSL is often confused with G.SHDSL and unfortunately , in Europe G.SHDSL was standardized by ETSI using the name 'SDSL' . This ETSI variant is compatible with the ITU -T G.SHDSL standardized regional variant for Europe . Equipment routing SDSL support is usually proprietary equipment which only speaks to SDSL equipment from the same vendor , or to SDSL equipment from other vendors that use the same DSL chipset . Most new installations use G.SHDSL equipment instead of SDSL . See also Symmetric High-speed Digital Subscriber Line ( G.SHDSL ) Digital Subscriber Line ( DSL ) Asymmetric Digital Subscriber Line ( ADSL ) ISDN This computer network -related article is a stub . You can help Wikipedia by expanding it . Categories : Computer network stubs | Digital Subscriber Line In other languages : Bosanski | Deutsch | Español | Français | Nederlands | Norsk ( bokmål ) | Polski | Português | Svenska | Türkçe 