19 - Troubleshooting Wireless Client Connectivity

Question 1

___ tools monitor the RF spectrum.

Answer 1

sprectrum analysis

Question 2

Performing ___ improves the performance, reliability, and security of wireless services, and keeps the cost of managing the network low by troubleshooting performance and connectivity issues quickly.

Answer 2

spectrum analysis

Question 3

Third party spectrum analysers include:

Answer 3

• Metageek Chanalyzer
o Can be used with its own RF spectrum adapter (wi-spy) or by connecting to a Cisco AP in spectrum expert mode
o Measures RF signals in the 2.4 and 5 GHZ spectrum. Can detect overlapping channels in the RF spectrum
o Windows based
• Ekahau Site Survey (ESS)
o Network planning tool to perform site surveys, analysis and report on existing wifi networks and support troubleshooting
o Can help analysie signal strength and SNR, noise and interference, roaming, RTT and packet loss, and spectrum power and channel utilisation in the area

Question 4

Cisco spectrum analysers include:

Answer 4

Cisco CleanAir
o Enabled from the WLC so that the AP can scan the RF. Not only identifies RF interference but also indicates which APs have reported the interference to better locate it.
Cisco Spectrum Expert GUI
o Helps identify potential interferers.
o Can use a laptop with a sensor card with either internal or external antennas or connect to a remote sensor.
Cisco Meraki RF Spectrum
o Have a dedicated radio for analysing the RF spectrum.
o From the Meraki dashboard, the 2.4 and 5 GHz spectrum can be analysed

Question 5

A ___ allows you to find wireless networks wherever they are and display Wi-Fi network-related information that includes network ranges, signal strength, channel numbers, and security levels such as secure or open.

Answer 5

Wi-Fi scanner

Question 6

There are several Wifi scanning tools that can be downloaded for laptops or handheld devices:

Answer 6

• MetaGeek insider (Windows, macOS)
• Wifi Analyser (Android)
• Apply AirPort Utility scanner (ios)

Question 7

__ breaks down network traffic to individual packets and decodes them to the appropriate Radio Frequency (RFC) or specification. There are two ways to obtain __s, spanning a port or using the wireless sniffer mode of an AP to obtain a wireless trace. When setting up an AP in wireless sniffer mode from a Cisco WLC, you simple enable sniffer mode, choose a channel, and specify the IP address of the capture analyser device.

Answer 7

Packet capture

Question 8

The ___ has a new monitoring dashboard that gives a single-window overview of the network devices that are connected to the controller.

Answer 8

controller GUI

Question 9

WLC show commands: Shows client MAC, AP associated to, WLAN ID, and radio

Answer 9

show client summary

Question 10

WLC show commands: Shows client username, associated AP, SSID, IP address, supported data rates, mobility state, security, and VLAN

Answer 10

show client detail

Question 11

WLC show commands: Shows the clients on a radio for an AP

Answer 11

show client ap 802.11{a | b} cisco_ap

Question 12

WLC show commands: Shows the clients on a radio for all APs

Answer 12

show client ap 802.11{a | b} all

Question 13

WLC show commands: Shows the latest trap log information

Answer 13

show traplog

Question 14

WLC show commands: Shows the message log and current log severity level

Answer 14

show logging

Question 15

WLC show commands: Shows radio networking settings (status, rates, supported, power, and channel)

Answer 15

show 802.11{a | b}

Question 16

WLC show commands: Shows WLAN information (name, security, status, and all settings)

Answer 16

show wlan

Question 17

WLC show commands: Shows AP detailed configuration settings by radio

Answer 17

show ap config 802.11{a | b} [summary] cisco_ap

Question 18

WLC show commands: Shows general AP configuration information

Answer 18

show ap config general

Question 19

WLC show commands: Shows all APs joined (MAC, IP, name, and join status)

Answer 19

show ap join stats summary all

Question 20

WLC show commands: Shows APs (model, MAC, IP address, country, and number of clients)

Answer 20

show ap summary

Question 21

WLC show commands: Shows WLAN IDs, interfaces, and SSID

Answer 21

show ap wlan 802.11{a | b} cisco_ap

Question 22

This command enables eight debug commands, plus a filter on the mac address that is provided. The eight debug commands show the most important details about client association and authentication.

Answer 22

debug client MAC

Question 23

___ represents the Nextgen cloud-based evolution of the Wireless Lan controller Config Analyser (WLCCA). It has new improved checks for WLCs, APs, Radio Frequency, Mobility Security, Mesh and Flex Configuration.

Answer 23

Wireless Config Analyser Express

Question 24

___ can be caused by adjacent 802.11 networks or other sources like microwave ovens, cordless phones, Bluetooth, TDD phones, wireless cameras and more, that operate in the same frequency

Answer 24

Interference

Question 25

What are the two potential reasons for interference?

Answer 25

cochannel interference, adjacent interference

Question 26

___ interference – AP coverage areas overlap and are configured in the same channel or channels with overlapping frequencies, connectivity issues can occur for clients in the overlapping area. To avoid this issue, change the channel number to a nonoverlapping channel or move the AP farther away.

Answer 26

cochannel

Question 27

___ interference – When APs are placed too close to each other or use high-output power levels, even when the APs are configured on nonoverlapping channels. Decrease the power of the AP to fix this issue.

Answer 27

adjacent channel

Question 28

If clients are reporting problems, a good place to start troubleshooting is at the Cisco __. The __ has a useful home screen called the monitoring dashboard that summarises its configuration.

Answer 28

WLC

Question 29

One section of the WLC GUI specifically helpful to troubleshooting client associations with an AP is the __ section of the __ menu

Answer 29

clients, monitor

Question 30

Network-side issues are typically evident when many users across the entire network are reporting connection problems. The first place to look in this case would be the __for a misconfiguration of some type.

Answer 30

Cisco WLC

Question 31

Client-side issues are typically evident when just one or two users are reporting a connection problem. In this case the ___ is probably not the problem but is something the user has done to their device.

Answer 31

wifi network

Question 32

The following are coming issues regarding VLAN and trunk misconfigurations:

Answer 32

• VLAN trunk between the switch and WLC is not configured to support the proper VLANs
• The switchport to which the AP is connected is configured to the wrong VLAN
• There is a mismatch between the native VLAN on the switch port and the native VLAN on the AP

Question 33

What are some common fixes AP discovery issues?

Answer 33

• Verify AP is getting a DHCP IP address
• Verify option 43 is set properly
• Verify the DNS server is reachable
• Verify the WLC management interface is reachable for Cisco AireOS (from APs)
• Verify the Cisco Wireless Control Module management interface is reachable for Cisco IOS XE (from APs)

Question 34

What are some common fixes AP join issues?

Answer 34

• The WLC and AP time are outside the certificate validity interval: verify that the WLC can reach the NTP server and has the correct date and time
• Mismatch is regulatory domain: The AP regulatory domain must match the WLC regulatory domain
• AP not able to join WLC, firewall blocking necessary ports: Configure to allow CAPWAP
• Error message-dropping primary discovery request from AP: Verify the maximum number of APs for the WLC has not be exceeded.

Question 35

Many of the WLAN components rely on the __ for proper operation. The operations include redundancy, logging, AP joins, mobility group connectivity and others

Answer 35

time synchronisation

Question 36

To ensure proper time synchronisation operation:

Answer 36

• Verify each component has an NTP server that is defined and reachable.
• Verify that the timezone and daylight savings are set correctly

Question 37

WLCs are grouped in a common RF group for ___.

Answer 37

Radio Resource Management (RRM)

Question 38

If a WLC cannot join an RF group with automatic RF grouping, it is most likely because:

Answer 38

• RF group size is above capacity
• RF group name that is assigned to the WLC is different (spelling)
• There is no network path for hello message