DSL (Digital Subscriber Line, Digital Subscriber Line) is a combination of transmission technologies that use general traditional telephone lines as transmission media. It includes HDSL, ADSL, ADSL2+, VDSL, VDSL2, G.Fast, etc., and is generally called xDSL technology. The main difference between them is the difference in signal transmission speed and effective distance, as well as the difference in symmetry due to the difference between the uplink rate and the downlink rate.


The xDSL technology supports symmetric and asymmetric transmission modes on the user loops of traditional telephone networks (POTS) and integrated services digital networks (ISDN), which solves the so-called “last one” that often occurs between network service providers and end users. “Mile” transmission bottleneck problem. Since telephone subscriber circuits have been laid in large numbers, how to make full use of the existing telephone network infrastructure and realize high-speed access through copper twisted pair has become the research focus of the industry. Therefore, xDSL technology has quickly gained attention, and in some countries And the region has been widely used.



ADSL standards was published by ITU-T :The International Telecommunication Union’s Telecommunication Standardization Department (ITU-T) has formulated a series of communication protocols such as ITU-T G.992/993 as the xDSL technical standard for xDSL technology to ensure that communication equipment between countries can communicate without hindrance.


– G.994 Handshake procedures for DSL
– G.992.1 (G.dmt) Annex A, B and C
– G.992.2 (G.lite) Annex A and C
– ANSI T1.413
– G.992.3 ADSL2 Annex A, B, C, J, L and M
– G.992.5 ADSL2+ Annex A, B, C, J and M
– G.993.1 VDSL
– G.993.2 VDSL2
– G.993.5 G.vector
– G.998.1 ATM bonding
– G.998.2 PTM bonding
– G.998.4 G.INP
– G.9700/01 G.Fast
– G.993.2Amd 7-Alternative Electrical Length Estimation Method (AELEM)



Outside connection of local network
Comercial website building up
Integrated with Video conference setup
Wireless internet access
Connection with IP-VPN network building up