DSL – Digital Subscriber Line
A technology that allows digital signals to be transferred on standard telephone lines. There are different types of DSL, with the newer being faster.
ADSL / ADSL2+ – Asymmetric DSL
A technology that allows a maximum 1.5Mbps download and 256kbps upload speed for version 1.
The newer 2+ variant is rated at 24Mbps download and 1Mbps upload. However you must be very close to the exchange to achieve max speed. Hence, a more realistic speed for the majority of the population should average at 10Mbps download and 600kbps upload.
SHDSL – Symmetric High Bit-Rate DSL
This variant of DSL allows much a symmetric experience where the upload speed and download speed is the same at 2Mbps. Circuits may be bonded to create a 4Mbps link. However, to achieve 2Mbps the distance of the circuit must be no greater than 3km. Once the circuit exceeds this distance, the circuit will run at slower speeds. Maximum distance from exchange is 6km where the speed will fall down to 192kbps.
VDSL / VDSL2 – Very High Bit-rate DSL
A high speed, short distance DSL technology which allows speed of upto 18Mbps download and 16Mbps upload within the high rise building. The second variants of VDSL will allow speeds of 50Mbps to 100Mbps within the same building. This technology is very popular in countries like Korea where the internet is used for mass distribution of video and TV.