Cisco IOS Software Configuration Guide for Cisco Aironet Access Points, 12.2(13)JA
Glossary
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Glossary

Table Of Contents


Glossary

802.11
The IEEE standard that specifies carrier sense media access control and physical layer specifications for 1- and 2-megabit-per-second (Mbps) wireless LANs operating in the 2.4-GHz band.
802.11a
The IEEE standard that specifies carrier sense media access control and physical layer specifications for wireless LANs operating in the 5-GHz frequency band.
802.11b
The IEEE standard that specifies carrier sense media access control and physical layer specifications for 5.5- and 11-Mbps wireless LANs operating in the 2.4-GHz frequency band.


A
 
access point
A wireless LAN data transceiver that uses radio waves to connect a wired network with wireless stations.
ad hoc network
A wireless network composed of stations without Access Points.
antenna gain
The gain of an antenna is a measure of the antenna's ability to direct or focus radio energy over a region of space. High gain antennas have a more focused radiation pattern in a specific direction.
associated
A station is configured properly to allow it to wirelessly communicate with an Access Point.


B
 
backoff time
The random length of time that a station waits before sending a packet on the LAN. Backoff time is a multiple of slot time, so a decrease in slot time ultimately decreases the backoff time, which increases throughput.
beacon
A wireless LAN packet that signals the availability and presence of the wireless device. Beacon packets are sent by access points and base stations; however, client radio cards send beacons when operating in computer to computer (Ad Hoc) mode.
BOOTP
Boot Protocol. A protocol used for the static assignment of IP addresses to devices on the network.
BPSK
A modulation technique used by IEEE 802.11b-compliant wireless LANs for transmission at 1 Mbps.
broadcast packet
A single data message (packet) sent to all addresses on the same subnet.


C
 
CCK
Complementary code keying. A modulation technique used by IEEE 802.11b-compliant wireless LANs for transmission at 5.5 and 11 Mbps.
CCKM
Cisco Centralized Key Management. Using CCKM, authenticated client devices can roam from one access point to another without any perceptible delay during reassociation. An access point on your network provides wireless domain services (WDS) and creates a cache of security credentials for CCKM-enabled client devices on the subnet. The WDS access point's cache of credentials dramatically reduces the time required for reassociation when a CCKM-enabled client device roams to a new access point.
cell
The area of radio range or coverage in which the wireless devices can communicate with the base station. The size of the cell depends upon the speed of the transmission, the type of antenna used, and the physical environment, as well as other factors.
client
A radio device that uses the services of an Access Point to communicate wirelessly with other devices on a local area network.
CSMA
Carrier sense multiple access. A wireless LAN media access method specified by the IEEE 802.11 specification.


D
 
data rates
The range of data transmission rates supported by a device. Data rates are measured in megabits per second (Mbps).
dBi
A ratio of decibels to an isotropic antenna that is commonly used to measure antenna gain. The greater the dBi value, the higher the gain, and the more acute the angle of coverage.
DHCP
Dynamic host configuration protocol. A protocol available with many operating systems that automatically issues IP addresses within a specified range to devices on the network. The device retains the assigned address for a specific administrator-defined period.
dipole
A type of low-gain (2.2-dBi) antenna consisting of two (often internal) elements.
domain name
The text name that refers to a grouping of networks or network resources based on organization-type or geography; for example: name.com—commercial; name.edu—educational; name.gov—government; ISPname.net—network provider (such as an ISP); name.ar—Argentina; name.au—Australia; and so on.
DNS
Domain Name System server. A server that translates text names into IP addresses. The server maintains a database of host alphanumeric names and their corresponding IP addresses.
DSSS
Direct sequence spread spectrum. A type of spread spectrum radio transmission that spreads its signal continuously over a wide frequency band.


E
 
EAP
Extensible Authentication Protocol. An optional IEEE 802.1x security feature ideal for organizations with a large user base and access to an EAP-enabled Remote Authentication Dial-In User Service (RADIUS) server.
Ethernet
The most widely used wired local area network. Ethernet uses carrier sense multiple access (CSMA) to allow computers to share a network and operates at 10, 100, or 1000 Mbps, depending on the physical layer used.


F
 
file server
A repository for files so that a local area network can share files, mail, and programs.
firmware
Software that is programmed on a memory chip.


G
 
gateway
A device that connects two otherwise incompatible networks together.
GHz
Gigahertz. One billion cycles per second. A unit of measure for frequency.


I
 
IEEE
Institute of Electrical and Electronic Engineers. A professional society serving electrical engineers through its publications, conferences, and standards development activities. The body responsible for the Ethernet 802.3 and wireless LAN 802.11 specifications.
infrastructure
The wired Ethernet network.
IP address
The Internet Protocol (IP) address of a station.
IP subnet mask
The number used to identify the IP subnetwork, indicating whether the IP address can be recognized on the LAN or if it must be reached through a gateway. This number is expressed in a form similar to an IP address; for example: 255.255.255.0.
isotropic
An antenna that radiates its signal in a three-dimensional sphere.


M

 

MAC
Media Access Control address. A unique 48-bit number used in Ethernet data packets to identify an Ethernet device, such as an access point or your client adapter.
modulation
Any of several techniques for combining user information with a transmitter's carrier signal.
multipath
The echoes created as a radio signal bounces off of physical objects.
multicast packet
A single data message (packet) sent to multiple addresses.


O
 
omni-directional
This typically refers to a primarily circular antenna radiation pattern.
Orthogonal Frequency Division Multiplex (OFDM)
A modulation technique used by IEEE 802.11a-compliant wireless LANs for transmission at 6, 9, 12, 18, 24, 36, 48, and 54 Mbps.


P
 
packet
A basic message unit for communication across a network. A packet usually includes routing information, data, and sometimes error detection information.


Q
 
Quadruple Phase Shift Keying
A modulation technique used by IEEE 802.11b-compliant wireless LANs for transmission at 2 Mbps.


R
 
range
A linear measure of the distance that a transmitter can send a signal.
receiver sensitivity
A measurement of the weakest signal a receiver can receive and still correctly translate it into data.
RF
Radio frequency. A generic term for radio-based technology.
roaming
A feature of some Access Points that allows users to move through a facility while maintaining an unbroken connection to the LAN.
RP-TNC
A connector type unique to Cisco Aironet radios and antennas. Part 15.203 of the FCC rules covering spread spectrum devices limits the types of antennas that may be used with transmission equipment. In compliance with this rule, Cisco Aironet, like all other wireless LAN providers, equips its radios and antennas with a unique connector to prevent attachment of non-approved antennas to radios.


S
 
slot time
The amount of time a device waits after a collision before retransmitting a packet. Short slot times decrease the backoff time, which increases throughput.
spread spectrum
A radio transmission technology that spreads the user information over a much wider bandwidth than otherwise required in order to gain benefits such as improved interference tolerance and unlicensed operation.
SSID
Service Set Identifier (also referred to as Radio Network Name). A unique identifier used to identify a radio network and which stations must use to be able to communicate with each other or to an access point. The SSID can be any alphanumeric entry up to a maximum of 32 characters.


T
 
transmit power
The power level of radio transmission.


U
 
UNII
Unlicensed National Information Infrastructure—regulations for UNII devices operating in the 5.15 to 5.35 GHz and 5.725 to 5.825 GHz frequency bands.
UNII-1
Regulations for UNII devices operating in the 5.15 to 5.25 GHz frequency band.
UNII-2
Regulations for UNII devices operating in the 5.25 to 5.35 GHz frequency band.
UNII-3
Regulations for UNII devices operating in the 5.725 to 5.825 GHz frequency band.
unicast packet
A single data message (packet) sent to a specific IP address.


W
 
WDS
Wireless Domain Services (WDS). An access point providing WDS on your wireless LAN maintains a cache of credentials for CCKM-capable client devices on your wireless LAN. When a CCKM-capable client roams from one access point to another, the WDS access point forwards the client's credentials to the new access point with the multicast key. Only two packets pass between the client and the new access point, greatly shortening the reassociation time.
WEP
Wired Equivalent Privacy. An optional security mechanism defined within the 802.11 standard designed to make the link integrity of wireless devices equal to that of a cable.
WLSE
Wireless LAN Solutions Engine. The WLSE is a specialized appliance for managing Cisco Aironet wireless LAN infrastructures. It centrally identifies and configures access points in customer-defined groups and reports on throughput and client associations. WLSE's centralized management capabilities are further enhanced with an integrated template-based configuration tool for added configuration ease and improved productivity.
WNM
Wireless Network Manager.
workstation
A computing device with an installed client adapter.
WPA
Wi-Fi Protected Access (WPA) is a standards-based, interoperable security enhancement that strongly increases the level of data protection and access control for existing and future wireless LAN systems. It is derived from and will be forward-compatible with the upcoming IEEE 802.11i standard. WPA leverages TKIP (Temporal Key Integrity Protocol) for data protection and 802.1X for authenticated key management.