3Com HomeConnect 3CP4130 User Manual page 43

Hub
A conduit for information between devices that are part of a network. A hub
contains a number of ports which all participating devices (computers, printers,
scanners, etc.) in the network plug into. The hub then receives and directs
information to all segments of the LAN.
LAN
A computer network that spans a relatively small area. Most LANs are confined
to a single building or group of buildings. However, one LAN can be connected
to other LANs over any distance via telephone lines and radio waves. A system of
LANs connected in this way is called a wide-area network (WAN). Computers
connected to a LAN are able to share, not only data, but also expensive devices,
such as laser printers and scanners. Ethernet LANs are most common for PCs.
Data transmission is very fast on a LAN, but the distances and numbers of
computers that can be connected are limited.
LED (light emitting diode)
An electronic device or signal that lights up when electricity is passed through it.
Your Dual Link modem uses LEDs to indicate the status of important operations.
Modem (modulator-demodulator)
A modem is a device or program that enables a computer to transmit data over
telephone lines. The modem converts data which is stored digitally (in the
computer) to analog data (which is required for transmission over telephone lines)
and vice versa. Simply stated, "digital" data is based on discrete "on-off"
switching (1 and 0) whereas analog data consists of infinitely variable data, such
as sound waves.
Nac file
A "Nac file" is a file with the extension .nac. The file extension was coined by
U.S. Robotics from the words Network Application Code or Network Application
Card. It contains information essential to network communications and resides in
the Flash memory of your modem Dual Link. If you choose to install the "Instant
Update" utility from your modem's installation CD, the utility will search for and
download from the 3Com web site any update to the Nac file. Once you've
received an updated Nac file, you would install to the modem using the DL
manager.
NIC (network interface card)
An expansion board or adapter that you install or insert into a computer in order
to make it capable of communicating to a network. A common example is an
Ethernet LAN adapter.
IP (Internet Protocol)
Specifies the format of packets (pieces of data) and the addressing scheme. Most
networks combine IP with a higher-level protocol called Transport Control
Protocol (TCP), which establishes a virtual connection between a destination and
a source. IP by itself is like a postal system. Using it, you can "address a package
and drop it in the mail," but there's no direct link between you and the recipient.
TCP/IP, on the other hand, establishes a connection between two hosts so that
they can send messages back and forth for a period of time.