xDSL Technology
1. Designations are not acronyms, but CCITT recommendation numbers
2. 192 Kbps divides into two B channels (64 kbps), one D channel
(16 kbps) and link administration.
3. "Duplex" means data of the same rate both upstream and downstream
4. Requires two twisted-pair lines
5. Requires three twisted-pair lines
6. A new system called SDSL, for Single Line DSL, operates at 1.5
or 2.0 Mbps duplex over one line
7. Also called BDSL, VADSL, or, at times, ADSL. VDSL is ANSI
8. "Down" means downstream, from the network to the subscriber.
9. Future VDSL systems may have upstream rates equal to downstream,
but on much shorter lines.