Netcom NB9, NB9W

NB9/NB9W ADSL2+ VoIP Router 79

YML790 Rev8

splitterless A type of DSL installation where no splitter is installed, saving the cost of a service call by the telephone company.

Instead, each jack in the home carries both voice and data, requiring a microﬁlter for each telephone to prevent

interference from the data signal. ADSL is usually splitterless; if you are unsure if your installation has a splitter, ask

your DSL provider. See also splitter, microﬁlter.

subnet A subnet is a portion of a network. The subnet is distinguished from the larger network by a subnet mask which selects

some of the computers of the network and excludes all others. The subnet’s computers remain physically connected

to the rest of the parent network, but they are treated as though they were on a separate network. See also network

mask.

subnet mask A mask that deﬁnes a subnet. See also network mask.

TCP See TCP/IP.

TCP/IP Transmission Control Protocol/Internet Protocol The basic protocols used on the Internet. TCP is responsible for dividing

data up into packets for delivery and reassembling them at the destination, while IP is responsible for delivering the

packets from source to destination. When TCP and IP are bundled with higher-level applications such as HTTP, FTP,

Telnet, etc., TCP/IP refers to this whole suite of protocols.

Telnet An interactive, character-based program used to access a remote computer. While HTTP (the web protocol) and FTP

only allow you to download ﬁles from a remote computer, Telnet allows you to log into and use a computer from a

remote location.

TFTP Trivial File Transfer Protocol. A protocol for ﬁle transfers, TFTP is easier to use than File Transfer Protocol (FTP) but not

as capable or secure.

TTL Time To Live A ﬁeld in an IP packet that limits the life span of that packet. Originally meant as a time duration, the TTL

is usually represented instead as a maximum hop count; each router that receives a packet decrements this ﬁeld by

one. When the TTL reaches zero, the packet is discarded.

twisted pair The ordinary copper telephone wiring long 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 also 10BASE-T, 100BASE-T, Ethernet.

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 My ADSL Modem is equipped with a USB interface for connecting to a stand-alone PC.

VC Virtual Circuit A connection from your ADSL 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 also 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 also VC.

WAN Wide Area Network Any network spread over a large geographical area, such as a country or continent. With respect to

the My ADSL Modem, 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 also 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 also 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 also 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.