HDSL

The HDSL is a  Symmetrical connection technology DSL INTERNET, transfer speed Internet to the PC (dowload) Is the same as computer to the Web. It is the first DSL to have been developed it in 1990. The resulting solution HDSL leased lines (T1 in the U.S. and E1 in Europe) since it uses some of these connections (the son), her son uses 4 of the 24 available in T1 and 6 instead of 32 in E1.

This technique achieves a throughput up to 2 Mbps over twisted pair telephone three and 1.5 Mbps on four son. For cons, the flow can down to 384 kb / s according to the quality of the telephone line and distance from the point access (limited to 4.5 km but it can be increased with repeaters).

Network Technology HDSL 2, now deployed in Europe, use one pair for speed equivalent (2 Mb / s for Europe or 1.5 Mb / s for the Americas) on a distance of 2500 meters maximum. This type of Internet connection does not allow to use the phone on the same line.

These two technical Internet connection are being replaced by the ADSL 2 and VDSL (asymetric) or SDSL (depend of versions)

Related terms: adsl - SHDSL -ISDN