CompTIA® Network+ Exam Notes : Troubleshooting Common Wireless Connectivity And Performance Issues

5. Network Troubleshooting and Tools

5.4 Troubleshoot common wireless connectivity and performance issues

Scenario 1: A small office has a wireless Access Point with several computers connected to it. However, some of the users complain that the connection was slow at times. What are the likely reasons?

Antenna Mismatch and Wireless phone: Note that the connectivity was slow or intermittent. If there were any mode/SSID mismatch, there wouldn't be any communication at all. It is also likely that the wireless phones, filing cabinets, and antenna mismatch errors are adding to the problem.

Antenna Types:

There are broadly two types of wireless networking antennas. These are

  • Omni antenna
  • Yagi antenna.

Omni antennas, as the name implies are omni (omni means "all") directional. They radiate power in all directions uniformly. On the other hand, Yagi antennas are directional. These antennas radiate more power in a given direction and require alignment. Wrong alignment or misalignment may result in total communication loss. Omni antennas are used for access point communication. The mobile user may be located at any point within the radio distance. Therefore, there is no directional preference, and hence Omni antennas are used. Yagi antennas are used for back-haul networks. To connect different access points. By using directional antenna, you can increase the distance/bandwidth between the communication points.

Two frequently used measurement units of antenna gain are

  • dBd
  • dBi

dBd refers to measurement with respect to a dipole antenna. dBi refers to the measurement with respect to an isotropic antenna. Normally, dBd is used for low frequencies (typically below 1GHz).

Scenario 2: Paul is a member of accounting group. All other members of the accounting group are able to print to a network printer. He is not able to print to the network printer. His group permissions are set correctly. However, he is able to access File services and other servers. What is the most likely problem?

Solution: Note that all other members of the group are able to access the network printer. Therefore, it can be safely assumed that there is no problem with the group permissions. Also, Paul is able to access file services, which means that the IP address, subnet mask, and default gateway are configured properly. The most likely reason is that the User permissions for Paul are not configured correctly for access to the network printer.

Scenario 3: A network administrator has newly installed wireless network using WAP enabled router in a restaurant. WEP is enabled for security purpose. However, wireless client computers are not able to access the Internet. The link LEDs on the wireless network cards are solid. What is the likely problem?

Solution: Check WEP settings

Note that the link LEDs are ON. Therefore, there is no problem with physical connectivity. The next step would be to check whether the WEP (Wired Equivalent Privacy) settings are okay. WEP settings on the router and the computers accessing the WAP should match, otherwise the client computers may not be able to communicate with the router.

Wrong SSID/SSID mismatch:

Scenario 4: Several client computers are connected to a network using WAP (Wireless Access Point). The WAP , in turn, is connected to a broadband Internet modem through a router. However, none of the computers on the wireless LAN are able to access the Internet during specific times. What is the likely reason?

Solution: Note that the wireless computers are able to communicate over the Internet intermittently. Therefore, the problem with IP address, MAC address or SSID can be ruled out. It is likely that the connectivity between the WAP and the router is intermittent, and needs to be checked.

Scenario 5: A user reports that the wireless network is slow and is able to see and access shared folders that not known to the user. Other wireless users do not see any problem. What is the likely reason?

Solution: It is most likely that the SSID is not configured properly on the users computer. If there is any problem with WAP device, other users would have had problems.

Scenario 6: Several client computers are connected to a network using WAP (Wireless Access Point). The WAP in turn is connected to a broadband Internet modem through a router. Only one of the computers is not able to access the Internet, nor able to see other computers on the wireless network. Other computers on the wireless LAN are functioning normally. Which of the following is the likely reason?

Solution: SSID (short for service set identifier) is a 32-character unique identifier attached to the header of packets when a host connects to a Wireless LAN. The SSID differentiates one WLAN (Wireless LAN) from another, so all access points and all devices attempting to connect to a specific WLAN must use the same SSID. An SSID is also referred to as a network name because essentially it is a name that identifies a wireless network.

If the connectivity between the WAP and the router is bad, then none of the computers on the wireless LAN would have worked.

Scenario 7: An office user is able to access local network drives over the WiFi, but unable to access the Internet. A sysadmin troubleshoots the issue and observes the following output of the ipconfig command:

output of ipconfig command

What would MOST likely allow the Internet to be accessed?

Solution: The user computer is connected to the WiFi as well as the LAN adapter. He should be able to access the Internet by disabling WiFi adapter. Most apps default to WiFi for accessing the Internet. Alternatively, you need ForceBindIP if you want to specifically force particular applications to use a particular adapter, rather than letting Windows sort it out itself.

Wireless Access Point Configuration and Security Mismatch:

Example 1. Configure the SSID of wireless access point to "netplus" Network Name (SSID) is basically the device's wireless network name and is one way of securing your wireless network. The SSID is shared by all devices in your wireless network and therefore, has to be unique since this will identify your wireless network from the rest.

To change the wireless network name of your router, follow the steps below.

images/pin-icon.png

Note: SSIDs are case sensitive and can contain up to 32 alphanumeric characters. Do not include spaces in your SSIDs.

Solution: 1. Click on AP1 in the network diagram , this will pop-up Graphical Device Interface (GDI) of AP1.

To change the wireless network name of your router step 1

2. In Wireless Access Point window click "Wireless" tab

To change the wireless network name of your router step 2

3. In Wireless tab window look for "Wireless Network Name" (SSID), and enter the SSID name "netplus" in the box provided. Click on "Save & Exit" button.

To change the wireless network name of your router step 3

Example 2: Configure the Ip address and subnet mask of wireless access point to 192.168.1.3 and 255.255.255.0 respectively.

Solution: Assigning a static IP address on an access point allows you to use the same IP address all the time regardless of where it is connected, making it easier to access its web-based setup page for any configuration changes. Besides, if the WAP is acting as a gateway, you need to assign the IP address to the WAP statically, as the connected workstations will have this IP address as their default gateway.

To configure IP address and subnet mask of wireless Access Point follow below steps

1. Click on AP1 in the network diagram , this will pop-up Graphical Device Interface (GDI) of AP1.

To configure IP address and subnet mask of wireless Access Point step 1

2. Set the IP address as 192.168.1.3 in Local IP address field and enter subnet mask as 255.255.255.0 and click "Save & Exit" button.

To configure IP address and subnet mask of wireless Access Point step 2
images/pin-icon.png

Note: The exercise is typical for a particular brand of home router and may differ slightly from device to device. When you are configuring any other brand/make routers, please read the manufacturer's documentation provided along with the device.

For more labs and examples you can download Network+ LabSim from the following link.

http://www.simulationexams.com/LabSim/network-lab-simulator.htm

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