19216811.liveChapter 7: Glossary
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twisted pair
The ordinary copper telephone wiring used by telephone companies. It
contains one or more wire pairs twisted together to reduce inductance and
noise. Each telephone line uses one pair. In homes, it is most often
installed with two pairs. For Ethernet LANs, a higher grade called Category
3 (CAT 3) is used for 10BASE-T networks, and an even higher grade called
Category 5 (CAT 5) is used for 100BASE-T networks. See
10BASE-T,
100BASE-T, Ethernet
.
unnumbered interfaces
An unnumbered interface is an IP interface that does not have a local
subnet associated with it. Instead, it uses a
router-id
that serves as the
source and destination address of packets sent to and from the router.
Unlike the IP address of a normal interface, the router-id of an
unnumbered interface is allowed to be the same as the IP address of
another interface. For example, the WAN unnumbered interface of your
device uses the same IP address of the LAN interface (192.168.1.1).
The unnumbered interface is temporary – PPP or DHCP will assign a ‘real’
IP address automatically.
upstream
The direction of data transmission from the user to the Internet.
USB
Universal Serial Bus
A serial interface that lets you connect devices such as printers, scanners,
etc. to your computer by simply plugging them in. The
CopperJet
can be
equipped with a USB interface for connecting to a stand-alone PC.
VC
Virtual Circuit
A connection from your DSL router to your ISP.
VCI
Virtual Circuit Identifier
Together with the Virtual Path Identifier (VPI), the VCI uniquely identifies a
VC. Your ISP will tell you the VCI for each VC they provide. See
VC
.
VPI
Virtual Path Identifier
Together with the Virtual Circuit Identifier (VCI), the VPI uniquely identifies
a VC. Your ISP will tell you the VPI for each VC they provide.
See
VC
.
WAN
Wide Area Network
Any network spread over a large geographical area, such as a country or
continent. With respect to the CopperJet, WAN refers to the Internet.
Web browser
A software program that uses Hyper-Text Transfer Protocol (HTTP) to
download information from (and upload to) web sites, and displays the
information, which may consist of text, graphic images, audio, or video, to
the user. Web browsers use Hyper-Text Transfer Protocol (HTTP). Popular
web browsers include Netscape Navigator and Microsoft Internet Explorer.
See
HTTP, web site, WWW
.
Web page
A web site file typically containing text, graphics and hyperlinks (cross-
references) to the other pages on that web site, as well as to pages on
other web sites. When a user accesses a web site, the first page that is
displayed is called the
home page
. See
hyperlink, web site
.
Web site
A computer on the Internet that distributes information to (and gets
information from) remote users through web browsers. A web site typically
consists of web pages that contain text, graphics, and hyperlinks. See
hyperlink, web page
.
WWW
World Wide Web. Also called
(the) Web.
Collective term for all web sites
anywhere in the world that can be accessed via the Internet.