User's Manual

Broadcast SSID: Used to allow an access point to respond to clients on a wireless network by

sending probes.

Data Rate (Information Rate): Not all bits carry user information. Each group (packet) of bits

contains headers, trailers, echo control, destination information, and other data required by the

transmission protocol. It is important to understand the difference between bit rate and data rate,

since the overhead information may consume more than 40% of the total transmission. This

difference is common to many such data systems, including Ethernet.

Direct-Sequence Spread Spectrum (DSSS) and Frequency-Hop Spread Spectrum (FHSS):

Two incompatible technologies used in radio transmission.

Extensible Authentication Protocol (EAP): An authentication protocol that supports multiple

authentication methods, such as Kerberos, passwords, or smart cards. Cisco's authentication

protocol, LEAP, is based on EAP, an extension to PPP (Point-to-Point Protocol).

Encryption: Scrambling data so that only the authorized recipient can read it. Usually a key is

needed to decrypt the data.

Extended Service Set IDentifier (ESSID): A type of unique identifier applied to both the AP

and the wireless PC Card that is attached to each packet. This allows the AP to recognize each

wireless client and its traffic.

Frequencies: Strike a piano key and you generate a tone. Pick up the tone with a microphone

and your tone turns in to a “vibrating” or “cycling” electronic signal. The rate of vibration

depends on the key struck. In electronics we refer to this rate of vibration as the number of

“cycles per second.” The formal term for this value is Hertz. As we move up in rate, such as in

the Broadcast Band, we can use Kilohertz (KHz) to represent 1,000 Hz, or Megahertz (MHz) to

represent 1,000,000 Hz. Continuing much further upward, we finally reach 1,000,000,000 Hz,

which we can fortunately shorten to a Gigahertz (GHz). These frequencies are the home of both

802.11a (5 GHz) and 802.11b (2.4 GHz).

Independent Basic Service Set Identifier (IBSSID): Used to identify a wireless network

configured to allow each wireless client to communicate directly with each other without an

access point.

Independent Network: A network that provides (usually temporarily) peer-to-peer connectivity

without relying on a complete network infrastructure.

Infrastructure Mode: A wireless network centered around an access point. In this environment,

the access point not only provides communication with the wired network but also mediates

wireless network traffic in the immediate neighborhood.

Institute of Electrical and Electronics Engineers (IEEE): An organization involved in setting

computing and communications standards.

ISM Bands: A series of frequency bands, set aside by the FCC for Industrial, Scientific and

Medical applications. Users of these bands operate equipment on a shared basis, meaning that

they must expect, and accept interference from other legal users. Products manufactured for

ISM Band use must be approved by the FCC, but the user does not have to be licensed. In

addition to WLAN, ISM bands support cordless phones, microwave ovens, baby monitors, toys,

ham radio transceivers, and other wireless services.

Kerberos: An authentication system enabling protected communication over an open network

using a unique key called a ticket.

Media Access Control (MAC) Address: A hardwired address applied at the factory. It uniquely

identifies network hardware, such as a wireless PC Card, on a LAN or WAN.