Administration Manual ip500pbxw – English
153
subnet
A subnet is a portion of a network. The subnet is distinguished from the larger network by a subnet
mask that 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 network mask.
subnet mask
A mask that defines a subnet. See network mask.
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.
TKIP
Temporal Key Integrity Protocol (TKIP) provides WPA with a data encryption function. It ensures
that a unique master key is generated for each packet, supports message integrity and sequencing
rules and supports re-keying mechanisms.
triggers
Triggers are used to deal with application protocols that create separate sessions. Some
applications, such as NetMeeting, open secondary connections during normal operations, for
example, a connection to a server is established using one port, but data transfers are performed
on a separate connection. A trigger tells the device to expect these secondary sessions and how to
handle them.
Once you set a trigger, the embedded IP address of each incoming packet is replaced by the
correct host address so that NAT can translate packets to the correct destination. You can specify
whether you want to carry out address replacement, and if so, whether to replace addresses on
TCP packets only, UDP packets only, or both.
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 system 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 units such as printers, scanners, etc. to your computer by
simply plugging them in.
VC
Virtual
Circuit
A connection from your DSL router to your Service Provider.
VCI
Virtual Circuit Identifier
Together with the Virtual Path Identifier (VPI), the VCI uniquely identifies a VC. Your Service
Provider 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 Service
Provider 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 ip500pbxw, WAN refers to the Internet.
