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Glossary

SCALANCE WLC711

User Guide, V8.11, 07/2012, C79000-G8976-C260-03 A-5

Gigabit Ethernet The high data rate of the Ethernet standard, supporting data rates of 1 gigabit (1,000

megabits) per second.

GUI Graphical User Interface

Heartbeat message A heartbeat message is a UDP data packet used to monitor a data connection, polling to see

if the connection is still alive.

In general terms, a heartbeat is a signal emitted at regular intervals by software to

demonstrate that it is still alive. In networking, a heartbeat is the signal emitted by a Level 2

Ethernet transceiver at the end of every packet to show that the collision-detection circuit is

still connected.

Host (1) A computer (usually containing data) that is accessed by a user working on a remote

terminal, connected by modems and telephone lines.

(2) A computer that is connected to a TCP/IP network, including the Internet. Each host has

a unique IP address.

HTTP Hypertext Transfer Protocol is the set of rules for transferring files (text, graphic images,

sound, video, and other multimedia files) on the World Wide Web. A Web browser makes

use of HTTP. HTTP is an application protocol that runs on top of the TCP/IP suite of

protocols. (RFC2616: Hypertext Transfer Protocol -- HTTP/1.1)

HTTPS Hypertext Transfer Protocol over Secure Socket Layer, or HTTP over SSL, is a Web protocol

that encrypts and decrypts user page requests as well as the pages that are returned by the

Web server. HTTPS uses Secure Socket Layer (SSL) as a sublayer under its regular HTTP

application layering. (HTTPS uses port 443 instead of HTTP port 80 in its interactions with

the lower layer, TCP/IP.) SSL uses a 40-bit key size for the RC4 stream encryption

algorithm, which is considered an adequate degree of encryption for commercial exchange.

IBSS Independent Basic Service Set. See BSS. An IBSS is the 802.11 term for an adhoc network.

See adhoc network.

ICMP Internet Control Message Protocol, an extension to the Internet Protocol (IP) defined by

RFC792. ICMP supports packets containing error, control, and informational messages. The

PING command, for example, uses ICMP to test an Internet connection.

ICV ICV (Integrity Check Value) is a 4-byte code appended in standard WEP to the 802.11

message. Enhanced WPA inserts an 8-byte MIC just before the ICV. (See WPA and MIC)

IE Internet Explorer.

IEEE Institute of Electrical and Electronics Engineers, a technical professional association,

involved in standards activities.

IETF Internet Engineering Task Force, the main standards organization for the Internet.

Infrastructure Mode An 802.11 networking framework in which devices communicate with each other by first

going through an Access Point (AP). In infrastructure mode, wireless devices can

communicate with each other or can communicate with a wired network. (See ad-hoc mode

and BSS.)

Internet or IP telephony IP or Internet telephony are communications, such as voice, facsimile, voice-messaging

applications, that are transported over the Internet, rather than the public switched telephone

network (PSTN). IP telephony is the two-way transmission of audio over a packet-switched

IP network (TCP/IP network).

An Internet telephone call has two steps: (1) converting the analog voice signal to digital

format, (2) translating the signal into Internet protocol (IP) packets for transmission over the

Internet. At the receiving end, the steps are reversed. Over the public Internet, voice quality

varies considerably. Protocols that support Quality of Service (QoS) are being implemented

to improve this.

Table A-1 Networking Terms and Abbreviations (continued)

Term Explanation

1 2 ... 470 471 472 473 474 475 476 477 478 479 480 ... 491 492

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