Troubleshooting Wireless Networks (5.4) Flashcards
Bandwidth
o Theoretical speed of data going across the network
Throughput
o Actual speed of data on the network
CHECK PICTURE
Received Signal Strength Indication (RSSI)
▪ Estimated measure of the power level that a radio frequency client
device is receiving from a wireless access point or wireless router
Effective Equivalent Isotropic Radiated Power (EIRP)
▪ Maximum power radiated from an ideal isotropic antenna, given its
antenna gain, and the transmitter power of the radio frequency system
Decibels over isotropic (dBi)
▪ Tells signal strength being radiated from a wireless access point
Vertical Antenna
▪ Radio frequency waves extend outward in all directions away from the
antenna and the wireless access point at an equal power level
Dipole Antenna
▪ Produces radio frequency waves extending outward in two directions
Yagi Antenna
▪ A unidirectional antenna that sends the radio frequency waves in only
one direction
Parabolic Grid Antenna
▪ Allows the radio waves to be transmitted in only one direction over a
longer distance than a Yagi antenna
▪ Choose a parabolic or Yagi antenna for site-to-site connections
▪ For indoor use, you are more likely to use omnidirectional and
unidirectional antennas
Polarization
▪ The orientation of the electric field (or transmission) from the antenna
▪ Most Wi-Fi networks use vertical polarization
o Channel Utilization
▪ A statistic or measure of the amount of airtime utilization that occurs for
a particular frequency or channel
▪ Keep channel utilization under 30% to have a faster wireless network
▪ Access points and clients form a single broadcast domain when they
operate on the same channel
Clear Channel Assessment (CCA)
▪ Listens to see if another device is actively transmitting on the channel
before attempting to send frames on that channel
▪ High channel utilization leads to slower throughput for wireless networks
Site Survey
▪ Process of planning and designing a wireless network to provide the
required wireless solution
● Configure devices to use less utilized channels
● Ensure proper coverage of the entire work areas
● Ensure wireless network is not being blocked or interfering with
physical obstacles within the building
How does a site survey work?
- Wireless client sends a probe request to discover any 802.11
wireless networks in proximity to itself - Receiving access point checks to see if it can support the data rate
the client requested - Wireless client sends a low-level 802.11 authentication frame to
the access point to begin authentication - Access point receives authentication frame and responds with an
acknowledgement to continue the handshake - Wireless client chooses the access point it wants to associate with
and sends an association request - Access point processes the association request if the information
sent matches its capabilities - Client is fully connected and associated and can now conduct any
data transfer it needs and use the wireless network
Basics steps
● Scan airwaves ● Find access points ● Request association ● Authenticate ● Contact DHCP server ▪ Clients should be located in high signal strength areas to speed up the association process