Single-pair high-speed digital subscriber line

The industry standard for SHDSL is defined by ITU-T recommendation G.991.2. This was first published in February 2001. SHDSL equipment is also known by the standard's draft name of G.SHDSL. Major updates to G.991.2 were released in December 2003. Equipment conforming to the 2003 version of G.991.2 is often referred to by the standard's draft name of G.SHDSL.bis or just SHDSL.bis. The updated G.991.2 features: • Optional support for up to four copper pair connections (M-pair) • Optional extensions to allow user data rates up to 5696 kbit/s per pair, described in Annexes F and G • Optional support for dynamic rate repartitioning, allowing flexible change of the SHDSL data rate without service interruption, described in Annex E.10.3 • New payload definitions including Ethernet packet transfer mode (PTM), described in Annex E.11 SHDSL supersedes the older HDSL symmetric DSL technology defined in ITU-T G.991.1. SHDSL has largely been replaced by VDSL2 because of greater bandwidth, less interference and greater utilization. In Europe, a variant of SHDSL was standardized by the European Telecommunications Standards Institute (ETSI) using the name 'SDSL'. This ETSI variant is compatible with the ITU-T SHDSL standardized regional variant for Europe and must not be confused with the usage of the term SDSL in North America to refer to symmetric digital subscriber line. ==External links==