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Glossary - 5
IP. Internet Protocol. The IP part of the TCP/IP communications protocol. IP implements the network layer (layer 3) of the
protocol, which contains a network address and is used to route a message to a different network or subnetwork. IP
accepts “packets” from the layer 4 transport protocol (TCP or UDP), adds its own header to it and delivers a “datagram”
to the layer 2 data link protocol. It may also break the packet into fragments to support the maximum transmission unit
(MTU) of the network.
IP Address. (Internet Protocol address) The address of a computer attached to an IP network. Every client and server
station must have a unique IP address. A 32-bit address used by a computer on a IP network. Client workstations have
either a permanent address or one that is dynamically assigned to them each session. IP addresses are written as four
sets of numbers separated by periods; for example, 204.171.64.2.
IPX/SPX. Internet Package Exchange/Sequential Packet Exchange. A communications protocol for Novell. IPX is Novell’s
Layer 3 protocol, similar to XNS and IP, and used in NetWare networks. SPX is Novell's version of the Xerox SPP
protocol.
K
Key. A key is the specific code used by the algorithm to encrypt or decrypt the data. Also see, Encryption and Decrypting .
L
LASER. Light Amplification by Stimulated Emission of Radiation.The laser is an intense light source. Light from a laser is
all the same frequency, unlike the output of an incandescent bulb. Laser light is typically coherent and has a high energy
density.
Laser Diode. A gallium-arsenide semiconductor type of laser connected to a power source to generate a laser beam. This
laser type is a compact source of coherent light.
Laser Scanner. A type of bar code reader that uses a beam of laser light.
LCD. See Liquid Crystal Display .
LED Indicator. A semiconductor diode (LED - Light Emitting Diode) used as an indicator, often in digital displays. The
semiconductor uses applied voltage to produce light of a certain frequency determined by the semiconductor's particular
chemical composition.
Light Emitting Diode. See LED .
Liquid Crystal Display (LCD). A display that uses liquid crystal sealed between two glass plates. The crystals are excited
by precise electrical charges, causing them to reflect light outside according to their bias. They use little electricity and
react relatively quickly. They require external light to reflect their information to the user.
M
MDN. Mobile Directory Number. The directory listing telephone number that is dialed (generally using POTS) to reach a
mobile unit. The MDN is usually associated with a MIN in a cellular telephone -- in the US and Canada, the MDN and