Troubleshooting Enterprise WLAN: Techniques and Tools

This article discusses troubleshooting techniques and tools for enterprise WLAN. It covers the components of WLAN and how to diagnose issues using bottom-up, top-down, and divide-and-conquer approaches. It also explores common CMD commands and tools for network troubleshooting. The article is relevant for networking courses and students in computer science and IT-related fields.

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Table of contents:
1. Introduction……………………………………………………………………………………………1.0
1.1 components of WLAN………………………………………………………………………..1.1
2. Task 1………………………………………………………………………………………………………..2.0
2.1 setting up of enterprise WLAN……………………………………………………………..2.1
2.2 confirm WLAN exists……………………………………………………………………………..2.2
2.3 Bottom-up approach…………………………………………………………………………….2.3
2.4 Top-down technique………………………………………………………………………………..2.4
2.5 Divide & conquer…………………………………………………………………………………….2.5
3 Task 2……………………...............................................................................................3.0
3.1 Tool, command and methodology……………………………………………………………..3.1

NETWORKING
1 Introduction.
Montemurro,2012. Found that Network administration is a comprehensive process ranging from basic
physical network set up and configuration to the complexed software based administration even to
programming in the administration. Software based are those that the admins use already made
software for administration, the common software used are the CISCO based such as the WLC, WLCM
and Aeronet but they are not open source, for learning purposes, simulation software such as fiddler
and wireshark are commonly used. Network administration also extends to programming where the
admin writes programs in the provided language commonly java and python to control the network
devices in a network and the most common one is the administration using one selected node as the
admin computer by use of the command prompt for windows and for linux series, they already have
terminal interface where the admin needs to type in commands for administration.
Generally, an enterprise WLAN is made up of three basic components;
Access point:
It is the primary part for any Wi-Fi client to connect to a wired network either internet or intranet. A Wi-
Fi client scans for SSIDs broadcasted from the Access point, chooses an SSID and then connects it to the
network via standard verification process. Access point literally is that point where the server router or
server machine is placed actually the Access Point or the AP is the device itself
Authentication server(AAA):
This avails verification service to Wi-Fi clients not only by the use of user ID or password as
conservatively undertaken, but likewise by the use of user data in SIM or USIM of the smart device.
provides a network service that applications use to validate the more often, normally account names
and passwords, of their users. When a client submits a valid set of credentials, it receives a
cryptographic ticket that it can successively be used to access various services.

Verification is used as the basis for approval, which is the resolve whether a honor may be given to a
certain user or process, confidentiality, which keeps information from becoming open to non-authorized
persons, and non-refutation, which is the inability to deny having done something that was permitted to
be done based on the verification.
Main authentication algorithms are passwords Kerberos, and pk-encryption.
Wireless Intrusion Prevention System(WIPS):
Luo,2014. Found that WIPS senses blush APs or unapproved Wi-Fi devices in a WLAN and foils them
from accessing or invading the network, WIPS sensors observing all the packets that traverse via all the
Wi-Fi frequency bands in real-time and placed through the network. WIPS likens the MAC address of all
wireless access points or the APs on a network against the known autographs of pre-authorized, known
wireless access points and notifies the network administrator when a inconsistency is found. To
circumvent MAC address tricking, other high-end WIPS are capable of analyzing the sole radio frequency
signatures that wireless devices generate and deny access to unknown radio fingerprints.
AP controller:
It is basically a supervision system that supervises all APs. It gathers information from distinct APs and
examines them ensuring and maintaining the service quality of the whole wireless network. WLAN AP
controllers functions as the switch for all the wireless traffic directing to a specific destination as
intended just as the normal switch.
Create the WLAN manually since there is no cmd command for the creation of the WLAN.
Apparently there is no working command prompt command that creates WLAN all that is available is the
netsh command which is only capable of managing or rather administering the network this therefore
suggests the use of manual way of creating the WLAN in the machine as the steps are prescribed below.
2 Task 1
2.1 Setting up the enterprise WLAN

2.2 Confirm the existence of the WLAN via CMD using the;
The enterprise WLAN created is called HCK hence if it exists it will show that name when the command
below is executed to show all the WLAN profiles.
netsh wlan show profile command.

Sure the WLAN HCK was created and it exists in the WLAN profile displayed from the above command.
Try connecting to the newly created WLAN access point in the cmd again.
2.3 Bottom-up approach.
Diagnosing the controller using Bottom-up approach.
Bottom-up technique of network troubleshooting begins from the physical components of the network
and navigates all the way to the OSI model of the network. If no problem is found at the preceding layer
the process is re-done in the successive layers until the problem is identified. This approach is very
effective if the problem is thought to be physical issue within the components of the network. This
approach in the newly created WLAN could be used once the connection to the network is done and this
requires an Access point so the WLAN needs an AP for this.

Diagnosing the Access point.
Sometimes the AP or the adapter may be corrupted and the solution to this is to delete the entire profile
and then creating a new profile, this is done the command prompt that is for windows but for Kali Linux
it can be done straightly from the shell.
1 Opening the command prompt and run as the administrator.
2 write the netsh command; netsh wlan delete profile name= HCK and press enter.
These kind of problems may emanate from the use of outdated drivers hence the drivers may need to
be re-installed.
After the driver re-installation and updating is finished, enter the following commands in the CMD still
running as the administrator: netsh winsock reset
netsh int ip reset
ipconfig /release
ipconfig /renew
ipconfig /flushdns
Note: There is a need to restart the computer or the router after every command.

Once the commands have been executed correctly, check the wireless adapter on the machines if they
are enabled if not enable them and reset the router to new settings then connect.
Bottom-up diagrammatical representation.
Application

Client and Guest Access.
Client guest issues can be well diagnosed by the CMD command
Netsh wlan show wlanreport command and receive a html format report from which one can hover
every session then see the performance and problems.
Transport
Network
Data link
Physical start

2.4 Top-down technique.
In this kind of technique of troubleshooting requires one to begin from the Application layer downwards
just from implication of the name. If a layer is not in the desired condition the administrator inspects the
layer beneath it preceding. It is chosen in probabilistic assumptions that the problem might be in the
Application layer or the OSI layer. This approach is most suitable for small networks where the nodes are
not very many and thus there is no much trunking and subnetting.
Application
layer
Transport
layer
Network layer
Data link
Physical
layer
start

Top-down approach of troubleshooting is best done by the CISCO’s WLCM which provides 802.11
networking solutions for wireless enterprise networks for cisco 3700, cisco 3800, cisco 2800 router
series. WLCM allows for the management of up to six Aps.
Check status of the WLCM.
Using the show version command in the CLI of the WLCM to show compatibility with the installed
raoter.
The CLI displays many information there but is needed is the version hence;
ROM: System Bootstrap, Version 12.4(1r) [hqluong 1r], RELEASE SOFTWARE (fc1)
2800-ISR-TSWEB uptime is 50 minutes
System returned to ROM by power-on
System image file is "flash:c2800nm-advsecurityk9-mz.124-11.T.bin"
To find the status of the port
by use of service-module wlan-controller slot/port status command.
For a well configured WLCM the expected output should be;
Cisco WLAN Controller 3.2.116.21
Note: Incase changes need to be effected in the CLI WLCM, the administrator enters adminn instead of
the custom admin to be able to make any configuration adjustments.
Top-down approach and the AP issues.
This troubleshooting could easily be done portable tools to diagnose the SSID such as the Aironet client
utility. For Primary connectivity use the straight-through DB-9 cable for console connectivity. Sometimes
radio emission interrupts the normal operations of a wireless network thus when troubleshooting it is
necessary to check the proximity of Aps in the WLAN connection, this could be solved by putting the Aps
some significant meters apart or literally reducing the radiation.
Top-down approach and the client/guest problems.
Client and guest problems majorly arises from the conflict over resources and sometimes usually the
client adapter does not communicate, to troubleshoot and solve this, ensure that the adapter card is set
at interrupt request levels that the rest of the devices do not use. If still there is an issue navigate to the
windows Device manager properties windows and unmark the use automatic settings box, then enter
the IRQ and I/O addresses. If the conflict or the problem persists rather there would be a need to reset
windows NT manually.
1. Check Start > Programs > Administrative Tools (Common) > Windows NT Diagnostics.
2. select the Resources tab in Windows NT Diagnostics.

3. The IRQ column, check which of the IRQ numbers are not provided in the Resources window.
4. select I/O Port in the Resources window.
The card requires 64 contiguous I/O addresses, for instance, 0101 through 014f hexadecimal.
1. select Start > Settings > Control Panel.
2. Double-click the Network in the control panel.
3. select the adapters in the Network window.
4. Select Aironet adapter in the panel.
5. pick Properties.
6. select Interrupt in the Property panel in the Adapter window.
select an IRQ value which is not provided in the Resources tab of the Windows NT Diagnostics.
7. select I/O Base address in the property panel in the Adapter Setup.
select an I/O address which is not provided in the Resources window
8. click OK
2.5 Divide and conquer.
Divide and conquer does not involve much intuition as it is with the other troubleshooting techniques.
The network administrator starts from whichever layer he/she wants to start from which is of course
convincingly to be the root of the problem. From the start point the administrator can go either upwards
or downwards depending on which layer is most suspected to be causing issues in the network.
3 Task 2
3.1 Tool, command and methodology.
The common network troubleshooting tool is the windows command prompt. The windows CMD is
usually used in the bottom-up approach of troubleshooting and it can be used in various ways ranging
client side to the server side and even WLAN interface management. The basic CMD commands are
ipconfig/all to show all that pertains the IP
Tracert to trace the path of a packet
Ping command to test the functionality of the IP or the node
These goes to the more advanced commands such as the winsock which now resets the WLAN as shown
in the pictures above.

Task 3.
New temporary user unable to access internet.
Usually this is not an issue in the WLAN, the issue is within that specific node or the computer. Number
one solution to this problem is to un-install the system network drivers an reinstall the drivers.
Steps:
1. click Windows key + X
2. select device manager.
3. Expand the network adapter.
4. Right click on the driver and uninstall.
5. Restart the machine and check.

References:
Luo, H. (2014). U.S. Patent No. 8,817,757. Washington, DC: U.S. Patent and Trademark Office.
Montemurro, M. (2012). U.S. Patent No. 8,244,241. Washington, DC: U.S. Patent and Trademark
Office.