Appendix A: Glossary
Firewall
A hardware or software device that prevents unauthorized
access to a private network from the Internet. The DG9450
provides a built-in firewall.
Gateway
The device, usually a router, that connects devices on a given IP
subnet to other IP subnets.
Headend
The "central office" in an HFC network. The headend houses
both video and data equipment. In larger cable networks, a
"master" headend often feeds several "remote" headends to
provide distributed services.
HTTP
HyperText Transfer Protocol.
Hub
A box with several Ethernet connectors. Ethernet hubs provide
a common point of contact for all connected devices.
IP address
A number assigned to your computer by your service provider,
used to identify your computer to other systems on the
Internet.
ISDN
Integrated Services Digital Network. A digital telephony
standard that provides communication speeds about twice as
fast as standard dialup.
LAN
Local Area Network. A network that allows computers in a single
location (such as a building) to communicate with one another.
LED
Light Emitting Diode. A semi-conductor diode that emits light
when current is passed through it.
MAC address
A number that uniquely identifies any device connected to a
network. Your service provider uses your Data Gateway's MAC
address to authorize access to the Internet. The MAC address is
printed on a label affixed to your Data Gateway.
Protocol
A set of rules and formats that determines the communication
behavior of network entities at a given layer.
Proxy
A device or program that stands in between a server (for
example, a web site) and a client (your browser), providing
a way to relieve some of the burden from the server. For
example, your service provider may have a web proxy that
keeps copies of popular web pages; the proxy can send you
those pages instead of fetching them directly from the web site,
resulting in faster page loading and less network congestion.
RF
Abbreviation for Radio Frequency. Some literature refers to
coax as "RF cable" and the connectors as "RF connectors."
RJ-11
A standard 2-conductor modular connector, commonly used in
North America for connecting telephones.
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