Chapter 1 Flashcards
Which WLAN organization standardizes how data is transmitted over the frequencies defined by the FCC?
IEEE (Institute of Electronic and Electrical Engineers)
Which 802.11 standards are used by 2.4GHz? 5GHz?
2.4GHz (802.11, b, g, n).
5GHz (802.11a, n, ac)
What does ISM stand for? U-NII?
2.4GHz Industrial, Scientific, Medical.
5GHz Unlicensed-National Information Infrastructure
Which channels are known as U-NII 2E?
Channels 100-144
What is it called when two nearby APs use overlapping channels?
Co-channel interference
Which standard introduced channel bonding? What does it do?
The 802.11n standard introduced channel bonding. Channel bonding uses the frequency ranges of two channels and treats them as a single, wider channel.
What is the difference between Wave 1 and Wave 2 APs?
Wave 1 uses 3 spatial streams and can bond up to 4 channels for 80MHz-wide channels. Wave 2 uses up to 4 spatial streams and can bond 8 channels for 160MHz-wide channels. Also introduces MU-MIMO.
What speed is considered VHT?
Speeds upwards of 150Mbps are considered VHT. 802.11n added the term HT.
What two features allow WLAN systems to operate in the radar spectrum?
802.11h features Dynamic Frequency Selection and Transmit Power control.
What is the standard that provides QoS?
802.11e is used for QoS
Name the priorities for traffic from highest to lowest
Voice, video, best-effort and scavenger
What traffic does WMM prioritize?
Wireless Multimedia prioritizes voice and video
Which security standard is implemented by WPAv2?
802.11i
What 3 features are supported by 802.11i?
Authentication, encryption and hashing. Hashing detects if an attacker captures a packet, modifies the data, and then resends it. (Man-in-the-middle attack)
What is 802.11k?
Radio measurement standard. It improves a client’s search for nearby APs by creating an optimized list of channels that it picks an AP from when the signal strength of the current AP weakens.
What is 802.11v?
Improved transition between access points using a technique called Basic Service Set transition-management.
What types of frames are used to establish, control and maintain client connections?
Management frames
What type of frames use RTS/CTS and ACK frames to access the channel and acknowledge receipt of frames?
Control frames
What levels are considered a typical noise floor?
Between -90 dBm and -100 dBm
What is a duty cycle?
How often an interferer is active over a given time period
What is the horizontal plane?
The azimuth is an overhead view as if you were hovering over the AP. Also known as the H-plane.
What is the vertical plane?
The elevation plane shows a vertical, side view. Also known as the E-plane
True or false? Antennas do not draw power from the AP so they do not “add power” to the signal.
True.
What unit is used to measure the gain of an antenna?
dBi
Where is an AP’s RF power specified at?
At its antenna connector.
What dBm is equal to 100mW?
20 dBm is equal to 100mW.
0dBm is equal to how many mW?
0dBm = 1mW
What is the formula for EIRP?
Tx Power - cable loss + antenna gain = EIRP = The total RF output power of an AP.
What is the difference between BSS and ESS?
The BSS is the AP WLAN and all associated clients in that AP’s coverage area. The ESS is that but configured across multiple APs.
What is a major differentiator between Aruba and other vendor’s WLANs?
A user’s access to resources can be different through Role Based Access Control (RBAC) and Firewall policies.
What SNR level is considered low?
Low SNR is defined as being 30 dBm or lower. This means if a client’s signal strength is -70 dB and the noise floor was -100 dB, you’d have an SNR of 30 dBm.
