ADSLVDSL

ADSLVDSL refers to two families of digital subscriber line (DSL) technologies that deliver broadband over existing copper telephone lines: ADSL (asymmetric digital subscriber line) and VDSL (very-high-bit-rate digital subscriber line). Both use the same basic concept of originating from a central office or street cabinet and terminating at a customer’s modem, often sharing lines with voice service via filters or splitters.

ADSL is designed so that downstream speeds (to the user) are higher than upstream speeds, reflecting typical residential usage. Variants include ADSL2 and ADSL2+, which improve efficiency and maximum data rates. Typical ADSL speeds on standard loops are up to a few megabits per second downstream and lower upstream, while ADSL2+ can push downstream toward two dozen megabits per second on shorter loops. The actual rate depends on loop length, line quality, and service profiles.

VDSL offers substantially higher potential speeds over shorter copper distances. VDSL2, the common form today, can reach tens to around a hundred megabits per second downstream with corresponding upstream rates, but performance declines as loop length grows. Vectoring technology and bonding can improve performance and stabilize rates in some deployments. Real-world speeds vary with loop length, line condition, and network configuration.

Both ADSL and VDSL coexist with traditional voice service and typically require a DSL modem (customer premises equipment) and a DSLAM at the service provider end. In many deployments, fiber is brought to a cabinet (FTTC) and copper delivers the last mile to homes, which makes ADSL and VDSL practical interim/fixed solutions where fiber access is not available.