User manual

Glossary-10 Adit 3200 - Release 1.6
Glossary
modem
modem MOdulator-DEModulator, a device that takes digital computer signal, converts it to analog,
and sends it across the phone line. Another modem on the reverse does the exact opposite
action. Modems transfer data at different speeds or rates, called baud.
multiplexer Electronic equipment which allows two or more signals to pass over one communications
circuit. The circuit may be analog or digital
MUX See multiplexer
NetBIOS Network Basic Input/Output System.NetBIOS is a program that allows applications on
different computers to communicate within a Local Area Network (LAN).
network A set of computers linked to one another for data sharing, or the link itself.
Network Time Protocol
(NTP)
Network Time Protocol, developed to maintain a common sense of time among Internet
hosts around the world. Many systems on the Internet run NTP, and have the same time
(relative to Greenwich Mean Time).
Non-Return to Zero
(NRZ)
A binary encoding scheme in which ones and zeros are represented by opposite and
alternating high and low voltages and where there is no return to a zero (reference) voltage
between encoded bits.
Open Shortest Path First
(OSPF)
Short for Open Shortest Path First, an interior gateway routing protocol developed for IP
networks based on the shortest path first or link-state algorithm.
Routers use link-state algorithms to send routing information to all nodes in an
internetwork by calculating the shortest path to each node based on a topography of the
Internet constructed by each node. Each router sends that portion of the routing table (keeps
track of routes to particular network destinations) that describes the state of its own links,
and it also sends the complete routing structure (topography).
The advantage of shortest path first algorithms is that they results in smaller more frequent
updates everywhere. They converge quickly, thus preventing such problems as routing
loops and Count-to-Infinity (when routers continuously increment the hop count to a
particular network). This makes for a stable network.
Note: OSPF Version 2 is defined in RFC 1583. It is rapidly replacing RIP on the Internet.
packet A packet consists of the data to be transmitted and certain control information.
PAP Password Authentication Protocol
PAT Port Address Translation
PHY PHY as in physical specifications. OSI Physical Layer, which provides for transmission of
cells over a physical medium connecting two ATM devices.
ping Packet InterNet Grouper. PING is a program used to test whether a particular network
destination on the Internet is online (i.e. working) by repeatedly bouncing a "signal" off a
specified address and seeing how long that signal takes to complete the round trip. No
return signal - site is down or unreachable. Portion is returned - trouble with the connection.
PLAR Private Line, Automatic Ringdown. A leased voice circuit that connects two single
instruments together. When either handset is lifted, the other instrument automatically
rings.