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CCNA wireless 640-722
Official terms for Cisco CCNA wireless 640-722
174
Computer Networking
Professional
04/18/2015

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Term
802.1x
Definition
An IEEE standard that defines port-based access control for wired and wireless networks
Term
Absorption
Definition
The effect of an RF signal meeting a material that absorbs or attenuates the signal strength by some amount
Term
Access point (AP)
Definition
A device that provides wireless service for clients within its coverage area or cell
Term
Active scanning
Definition
A method used by wireless clients to actively scan for available APs by sending probe request frames
Term
Ad hoc network
Definition
See independent basic service set (IBSS)
Term
Air-quality index (AQI)
Definition
A scale from 0 to 100 that indicates how usable an 802.11 channel is, based on the number and intensity of interfering sources
Term
Amplifier
Definition
An active device that adds gain to an RF signal
Term
Amplitude
Definition
The height from the top peak to the bottom peak of a signal?s waveform; also known as the peak-to-peak amplitude
Term
Anchor controller
Definition
High availability offered by controllers running software release 7.3 or later and configured as failover pairs. One controller is active and supports the AP and client load, and the other controller is a hot standby. Stateful information about APs is synchronized between the active and standby units for an efficient failover.
Term
AP SSO
Definition
A logical link that can be configured to terminate CAPWAP tunnels from lightweight APs
Term
AP-manager interface
Definition
He process by which a wireless device becomes a functioning member of a BSS
Term
Asymmetric power problem
Definition
The scenario where the AP and a client use differing transmit power levels such that the messages sent by device 1 are received and understood by device 2, but the replies from device 2 are too weak to be understood by device 1.
Term
Attenuator
Definition
A passive device that introduces additional loss to an RF signal
Term
Authentication server (AS)
Definition
An 802.1x entity that authenticates users or clients based on their credentials, as matched against a user database. In a wireless network, a RADIUS server is an AS. A WLC can also be an AS.
Term
Authenticator
Definition
An 802.1x entity that exists as a network device that provides access to the network. In a wireless network, a WLC acts as an authenticator.
Term
Autonomous AP
Definition
A wireless AP operating in a standalone mode, such that it can provide a fully functional BSS and connect to the DS
Term
Back off timer
Definition
The random amount of time a wireless client must wait before attempting to transmit a frame
Term
Band
Definition
A contiguous range of frequencies
Term
Bandwidth
Definition
The range of frequencies used by a single channel or a single RF signal
Term
Barker 11 code
Definition
An 11-bit sequence of encoded bits that represent a single data bit
Term
Basic service set (BSS)
Definition
Wireless service provided by an AP to one or more associated clients
Term
Basic service set identifier (BSSID)
Definition
A unique MAC address that is used to identify the AP that is providing a BSS
Term
Beam width
Definition
A measure of the angle of a radiation pattern in both the E and H planes, where the signal strength is 3 dB below the maximum value
Term
Block acknowledgment
Definition
A feature used in 802.11n that permits a burst of data frames to be followed by a single acknowledgment message, improving throughput
Term
BSS basic rate
Definition
A basic data rate that is required to be supported between an AP and a wireless client
Term
CAPWAP Discovery Request
Definition
A message sent by a lightweight AP to discover one or more wireless LAN controllers. Any controllers that receive the request should return a CAPWAP Discovery Response message to the AP.
Term
CAPWAP Join Request
Definition
A message sent by a lightweight AP to a specific WLC indicating the AP?s desire to join or associate with the controller. If the AP is accepted, the WLC returns a CAPWAP Join Response message.
Term
Carrier signal
Definition
The basic, steady RF signal that is used to carry other useful information
Term
CCX Lite
Definition
A CCX certification program that is organized in modules, according to specific applications for wireless devices
Term
Cell (or BSA)
Definition
The area of wireless coverage provided by an AP; also known as the basic service area
Term
Channel
Definition
An arbitrary index that points to a specific frequency within a band
Term
Channel aggregation
Definition
An 802.11n feature that allows two 20-MHz OFDM channels to be aggregated or bonded into a single 40-MHz channel
Term
Channel reuse
Definition
The pattern of APs and their channels, arranged such that neighboring Aps never use the same channels
Term
Chip
Definition
A bit produced by a coder
Term
Cisco Clean Air
Definition
Wireless technology used to detect, classify, report, and react to non-802.11 interference
Term
Cisco Compatibility Extensions (CCX)
Definition
A wireless device certification that verifies compatibility with a set of Cisco developed features. CCX is defined in five versions.
Term
Clear channel assessment (CCA)
Definition
The process a wireless devices uses to determine whether a channel is clear and available to use
Term
Client SSO
Definition
High availability offered by controllers running Software Release 7.5 or later and configured as failover pairs. Stateful information about clients associated with the primary controller is synchronized to the secondary standby unit for a transparent failover.
Term
Cluster ID
Definition
A unique identifier that a WLC assigns to a non-802.11 device found to be interfering with an AP. See also pseudo-MAC address.
Term
Co-channel interference
Definition
RF signal interference caused by two or more transmitters using the same frequency or channel
Term
Coder
Definition
A function that converts data bits into multiple encoded bits before transmission, to provide resilience against noise and interference
Term
Collision avoidance
Definition
The technique used by 802.11 devices to proactively avoid collisions on a channel
Term
Complementary Code Keying (CCK)
Definition
An encoding method that takes either 4 or 8 data bits at a time to create a 6-bit or 8-bit symbol, respectively. The symbols are fed into DQPSK to modulate the carrier signal.
Term
Contention window
Definition
The total amount of time a wireless client waits before transmitting a frame
Term
Controller interface
Definition
A logical connection that a wireless controller uses internally
Term
Controller port
Definition
A physical connection to an external switched network
Term
Counter/CBC-MAC Protocol (CCMP)
Definition
A wireless security scheme based on 802.11i that uses AES counter mode for encryption and CBC-MAC for data integrity
Term
Coverage hole
Definition
An area that is left without good RF coverage. A coverage hole can be caused by a radio failure or a weak signal in an area.
Term
DBd
Definition
The gain of an antenna, measured in dB, as compared to a simple dipole antenna
Term
DBi
Definition
The gain of an antenna, measured in dB, as compared to an isotropic reference antenna
Term
DBm
Definition
The power level of a signal measured in dB, as compared to a reference signal power of 1 milliwatt
Term
DCA
Definition
Dynamic channel allocation; an RRM algorithm that monitors APs in an RF group and adjusts their channel assignment based on poor RF conditions
Term
Decibel (dB)
Definition
A logarithmic function that compares one absolute measurement to another
Term
Delivery traffic indication message (DTIM)
Definition
A beacon sent at regular intervals that indicates whether buffered broadcast and multicast frames will be sent for clients that have been in a power save mode
Term
Demodulation
Definition
The receiver?s process of interpreting changes in the carrier signal to recover the original information being sent
Term
Differential binary phase shift keying (DBPSK)
Definition
A modulation method that takes 1 bit of encoded data and changes the phase of the carrier signal in one of two ways
Term
Differential quadrature phase shift keying (DQPSK)
Definition
A modulation method that takes 2 bits of encoded data and changes the phase of the carrier signal in one of four ways
Term
Diffraction
Definition
The effect of an RF signal approaching an opaque object, causing the electromagnetic waves to bend around the object
Term
Dipole
Definition
An omnidirectional antenna composed of two wire segments
Term
Direct sequence spread spectrum (DSSS)
Definition
A wireless LAN method where a transmitter uses a single fixed, wide channel to send data
Term
Directional antenna
Definition
A type of antenna that propagates an RF signal in a narrow range of directions
Term
Distributed coordination function (DCF)
Definition
The method used by each wireless device to coordinate the use of a wireless channel
Term
Distribution system (DS)
Definition
The wired Ethernet that connects to an AP and transports traffic between a wired and wireless network
Term
Distribution system port
Definition
A physical interface that connects a wireless controller to a switched network and carries both AP and management traffic
Term
Duty cycle
Definition
A measure of the percentage of time a device transmits on a given frequency
Term
Dynamic interface
Definition
An internal logical link that connects a VLAN to a WLAN. Traffic passing through a dynamic interface also passes through a VLAN on a distribution system port.
Term
Dynamic rate shifting
Definition
A mechanism used by an 802.11 device to change the modulation coding scheme (MCS) according to dynamic RF signal conditions
Term
EAP Flexible Authentication by Secure Tunneling (EAP-FAST)
Definition
A Cisco authentication method that is based on EAP and uses a PAC as a credential for outer authentication and a TLS tunnel for inner authentication
Term
EAP-TLS
Definition
An authentication method that uses digital certificates on both the server and the supplicant for mutual authentication. A TLS tunnel is used during client authentication and key exchanges.
Term
Effective isotropic radiated power (EIRP)
Definition
The resulting signal power level, measured in dBm, of the combination of a transmitter, cable, and an antenna, as measured at the antenna
Term
Enterprise mode
Definition
802.1x EAP-based authentication requirement for WPA or WPA2
Term
E plane
Definition
The ?elevation? plane passing through an antenna that shows a side view of the radiation pattern
Term
Event-Driven RRM (ED-RRM)
Definition
Using Cisco CleanAir to trigger the RRM DCA process automatically, as interference is detected
Term
Extended service set (ESS)
Definition
Multiple APs that are connected by a common switched infrastructure
Term
Extensible Authentication Protocol (EAP)
Definition
A standardized authentication framework that is used by a variety of authentication methods
Term
Foreign controller
Definition
The current controller a client is associated with after a Layer 3 intercontroller roam occurs. Traffic is tunneled from the foreign controller back to an anchor controller so that the client retains connectivity to its original VLAN and subnet.
Term
Free-space path loss
Definition
The degradation of an RF signal?s strength as it travels through free space
Term
Frequency
Definition
The number of times a signal makes one complete up and down cycle in 1 second.
Term
Frequency hopping spread spectrum (FHSS)
Definition
A wireless LAN method where a transmitter ?hops? between frequencies all across a band
Term
Fresnel zone
Definition
The elliptical shaped space between a transmitter and receiver that must be kept clear of objects, else the RF signal will be degraded
Term
Gain
Definition
A measure of how effectively an antenna can focus RF energy in a certain direction
Term
Guard interval (GI)
Definition
The amount of time required between OFDM symbols to prevent intersymbol interference. In 802.11n, the guard interval can be reduced from 800 ns to 400 ns.
Term
Hertz (Hz)
Definition
A unit of frequency equaling one cycle per second
Term
High throughput (HT)
Definition
The techniques defined in 802.11n and used to scale performance to a maximum of 600 Mbps
Term
H plane
Definition
The ?azimuth? plane passing through an antenna that shows a top-down view of the radiation pattern
Term
In phase
Definition
The condition when the cycles of two identical signals are in sync with each other
Term
Independent basic service set (IBSS)
Definition
An impromptu wireless network formed between two or more devices without an AP or a BSS; also known as an ad hoc network
Term
Infrastructure mode
Definition
The operating mode of an AP that is providing a BSS for wireless clients
Term
Intercontroller roaming
Definition
Client roaming that occurs between two APs that are joined to two different controllers
Term
Interframe space
Definition
The amount of time the 802.11 standard defines to separate adjacent frames on a channel
Term
Intersymbol interference (ISI)
Definition
Data corruption caused by OFDM symbols arriving too close together at a receiver, usually caused by signals that take different paths from transmitter to receiver
Term
Intracontroller roaming
Definition
Client roaming that occurs between two APs joined to the same controller
Term
IP Setup Utility (IPSU)
Definition
A Cisco software tool that can be used to find an autonomous AP?s IP address or to set its IP address and SSID
Term
Isotropic antenna
Definition
An ideal, theoretical antenna that radiates RF equally in every direction.
Term
Layer 2 roam
Definition
An intercontroller roam where the WLANs of the two controllers are configured for the same Layer 2 VLAN ID; also known as a local-to-local roam.
Term
Layer 3 roam
Definition
An intercontroller roam where the WLANs of the two controllers are configured for different VLAN IDs; also known as a local-to-foreign roam. To support the roaming client, a tunnel is built between the controllers so that client data can pass between the client?s current controller and its original controller.
Term
Lightweight EAP (LEAP)
Definition
A legacy Cisco proprietary wireless security method
Term
Link aggregation group (LAG)
Definition
A grouping or bundling of multiple physical links into a single logical link
Term
Link budget
Definition
The cumulative sum of gains and losses measured in dB over the complete RF signal path; a transmitter?s power level must overcome the link budget so that the signal can reach a receiver effectively
Term
Management frame protection (MFP)
Definition
A method developed by Cisco to protect wireless clients and APs from attacks involving spoofed management frames
Term
Management interface
Definition
A logical link that is used for normal management traffic. If an AP-manager interface is not configured, the management interface also terminates CAPWAP tunnels from APs.
Term
Maximal-ratio combining (MRC)
Definition
An 802.11n technique that takes multiple copies of a signal, received over multiple antennas, and combines them to reconstruct the original signal.
Term
Mesh network
Definition
A network of APs used to cover a large area without the need for wired Ethernet cabling; client traffic is bridged from AP to AP over a backhaul network
Term
Message integrity check (MIC)
Definition
A cryptographic value computed from the contents of a data frame and used to detect tampering.
Term
Mobility anchor
Definition
A wireless LAN controller that acts as the anchor or home base for remote wireless clients that are joined to a different controller
Term
Mobility group
Definition
A logical grouping of controllers that facilitates efficient client roaming and mobility
Term
Modulation
Definition
The transmitter?s process of altering the carrier signal according to some other information source
Term
Monopole
Definition
A very short omnidirectional antenna composed of a single wire segment set over a metal ground plane
Term
Multipath
Definition
Reflected copies of an RF signal arrive at a receiver after taking different paths through free space
Term
N+1 redundancy
Definition
High availability offered by N number of active controllers plus one idle standby controller.
Term
N+N redundancy
Definition
High availability offered by N number of active controllers. The AP load is distributed across the active controllers, so no additional backup controller is used.
Term
N+N+1 redundancy
Definition
High availability offered by N number of active controllers plus one idle standby controller.
Term
Narrowband
Definition
RF signals that use a very narrow range of frequencies
Term
Neighboring channel interference
Definition
RF signal interference caused by two or more transmitters using channels that are different, but do not completely overlap
Term
Network allocation vector (NAV)
Definition
An internal timer maintained by each wireless device that measures the number of timeslots before a transmission may be attempted
Term
Noise
Definition
Signals or RF energy that do not come from 802.11 sources
Term
Noise floor
Definition
The average power level of noise measured at a specific frequency
Term
Omnidirectional antenna
Definition
A type of antenna that propagates an RF signal in a broad range of directions in order to cover a large area
Term
Open authentication
Definition
An 802.11 authentication method that requires clients to associate with an AP without providing any credentials at all
Term
Open system authentication
Definition
A simple method used to verify that a wireless device uses 802.11 before it is permitted to join a BSS
Term
Orthogonal frequency-division multiplexing (OFDM)
Definition
A data transmission method that sends data bits in parallel over multiple frequencies within a single 20 MHz wide channel. Each frequency represents a single subcarrier.
Term
Out of phase
Definition
The condition when the cycles of one signal are shifted in time in relation to another signal
Term
Parabolic dish antenna
Definition
A highly directional antenna that uses a passive dish shaped like a parabola to focus an RF signal into a tight beam
Term
Passive scanning
Definition
A method used to scan for available APs by listening to their beacon frames
Term
Patch antenna
Definition
A directional antenna that has a planar surface and is usually mounted on a wall or column
Term
Personal mode
Definition
Pre-shared key authentication as applied to WPA or WPA2
Term
Phase
Definition
A measure of shift in time relative to the start of a cycle; ranges between 0 and 360 degrees
Term
Physical carrier sense
Definition
To determine whether a channel is available, a device simply listens to any signals that might be present.
Term
Point-to-point Bridge
Definition
An AP configured to bridge a wired network to a companion bridge at the far end of a line of sight path
Term
Polar plot
Definition
A round graph that is divided into 360 degrees around an antenna and into concentric circles that represent decreasing dB values. The antenna is always placed at the center of the plot.
Term
Polarization
Definition
The orientation (horizontal, vertical, circular, and so on) of a propagating wave with respect to the ground
Term
Primed controller address
Definition
The name or IP address of a controller that is configured in advance on an AP
Term
Protected access credential (PAC)
Definition
Special-purpose data that is used as an authentication credential in EAP-FAST
Term
Protected EAP (PEAP)
Definition
An authentication method that uses a certificate on the AS for outer authentication and a TLS tunnel for inner authentication. Clients can provide their credentials through either MS-CHAPv2 or GTC.
Term
Protection mechanism
Definition
Method of supporting backward compatibility between an advanced and a legacy wireless standard, such as 802.11g and 802.11b, respectively. For example, each 802.11g OFDM transmission is flagged with RTS/CTS messages sent in the lower-rate DSSS format.
Term
Pseudo-MAC address
Definition
A virtual MAC address that a controller assigns to each uniquely identified non-802.11 interferer so that it can be reported and displayed. See also cluster ID.
Term
Public Key Infrastructure (PKI)
Definition
An enterprise-wide system that generates and revokes digital certificates for client authentication
Term
Quadrature amplitude modulation (QAM)
Definition
A modulation method that combines QPSK phase shifting with multiple amplitude levels to produce a greater number of unique changes to the carrier signal. The number preceding the QAM name designates how many carrier signal changes are possible.
Term
Radiation pattern
Definition
A plot that shows the relative signal strength in dBm at every angle around an antenna
Term
Radio frequency (RF)
Definition
The portion of the frequency spectrum between 3 kHz and 300 GHz
Term
RADIUS server
Definition
An authentication server used with 802.1x to authenticate wireless clients
Term
Re-association
Definition
The process by which a wireless client changes its association from one BSS to another as it moves
Term
Received signal strength indicator (RSSI)
Definition
The measure of signal strength (in dBm) as seen by the receiver. RSSI is normally negative (0 to ?100) because the received signal is always a degraded form of the original signal that was sent.
Term
Reflection
Definition
The effect of an RF signal meeting a dense, reflective material, such that it is sent in a different direction
Term
Refraction
Definition
The effect of an RF signal meeting the boundary between two different materials, causing its trajectory to change slightly
Term
Repeater
Definition
A device that repeats or retransmits signals it receives, effectively expanding the wireless coverage area
Term
Rouge AP
Definition
A wireless AP that operates outside local administrative control
Term
RF group leader
Definition
A controller that is elected to handle all of the RRM algorithms for the entire RF group
Term
RF group
Definition
A logical grouping of wireless LAN controllers that operates as a single RF domain. RRM algorithms run on a per-RF group basis.
Term
RF group leader
Definition
A controller that is elected to handle all of the RRM algorithms for the entire RF group
Term
Roaming
Definition
The process a wireless client uses to move from one AP to another as it changes location
Term
Sensitivity level
Definition
The RSSI threshold (in dBm) that divides unintelligible RF signals from useful ones
Term
Service port
Definition
A physical nontrunking interface that connects a wireless controller to a switched network and carries only out-of-band management traffic
Term
Service set identifier (SSID)
Definition
A method used to authenticate a wireless device with a BSS by using a shared WEP key
Term
RRM
Definition
Radio Resource Management; a set of algorithms that are used to maintain a stable and optimum wireless network even in a changing RF environment
Term
Shared key authentication
Definition
A method used to authenticate a wireless device with a BSS by using a shared WEP key
Term
Signal-to-noise ratio (SNR)
Definition
A measure of received signal quality, calculated as the difference between the signals?s RSSI and the noise floor. A higher SNR is preferred.
Term
Spatial multiplexing
Definition
Distributing streams of data across multiple radio chains with spatial diversity
Term
Spatial stream
Definition
An independent stream of data that is sent over a radio chain through free space. One spatial stream is separate from others due to the unique path it travels through space.
Term
Spectrum analyzer
Definition
A device that sweeps through a range of frequencies and displays signals that it receives. The signal data can be processed and displayed in a variety of ways to assist in the analysis.
Term
Spread spectrum
Definition
RF signals that spread the information being sent over a wide range of frequencies
Term
Station (STA)
Definition
An 802.11 client device that is associated with a BSS
Term
Supplicant
Definition
An 802.1x entity that exists as software on a client device and serves to request network access
Term
Supported data rate
Definition
An 802.11 data rate that can be supported by a client when it associates with an AP
Term
Symbol
Definition
A complete group of encoded chips that represent a data bit
Term
Temporal Key Integrity Protocol (TKIP)
Definition
A wireless security scheme developed before 802.11i that provides a MIC for data integrity, a dynamic method for per-frame WEP encryption keys, and a 48-bit initialization vector. The MIC also includes a time stamp and the sender?s MAC address.
Term
TPC
Definition
Transmit power control; an RRM algorithm that adjusts the transmit power level of Aps to minimize cell overlap and interference
Term
Traffic indication map (TIM)
Definition
A list of the association IDs of wireless clients who are in a power save mode but have frames buffered. The TIM is included in beacon frames sent by an AP.
Term
Transmit beamforming (TxBF)
Definition
An 802.11n method to transmit a signal over multiple antennas, each having the signal phase carefully crafted, so that the multiple copies are all in phase at a targeted receiver
Term
Unscheduled automatic power save deliver (U-APSD)
Definition
The method defined in 802.11e and WMM that allows a wireless client to enter power save mode and then have buffered frames delivered whenever the client is ready to receive them
Term
Virtual carrier sense
Definition
The method by which a wireless device calculates that a channel is available, based on frame duration information that is used to set the NAV
Term
Virtual interface
Definition
A logical link used to support wireless clients with things like DHCP relay and web authentication
Term
Wavelength
Definition
The physical distance that a wave travels over one complete cycle
Term
Wi-Fi Protected Access (WPA)
Definition
A Wi-Fi Alliance standard that requires pre-shared key or 802.1x authentication, TKIP, and dynamic encryption key management; based on portions of 802.11i before its ratification
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