User guide

342
-----U-----
UTP. Unshielded twisted pair cable.
-----V-----
VDSL. Very high rate Digital Subscriber Line. VDSL transmits high speed
data over short reaches of twisted-pair copper telephone lines, with a range
of speeds depending upon actual line length. Both data channels will be
separated in frequency from bands used for POTS and ISDN, enabling ser-
vice providers to overlay VDSL on existing services. At present the two high
speed channels will also be separated in frequency.
VJ. Van Jacobson. Abbreviation for a compression standard documented in
RFC 1144.
VLAN. Virtual Local Area Network. A network of computers that behave as if
they are connected to the same wire even though they may be physically
located on different segments of a LAN. VLANs are configured in software
rather than hardware.
-----W-----
WAN. Wide Area Network. Private network facilities, usually offered by pub-
lic telephone companies but increasingly available from alternative access
providers (sometimes called Competitive Access Providers, or CAPs), that
link business network nodes.
WWW. World Wide Web.
-----X-----
XAuth. Extended Authentication. An extension to the Internet Key Exchange
(IKE) protocol, for IPSec tunnelling. Requires SafeHarbour IPsec tunneling
feature key.