Wi-Fi Technology is allowing to connect with your LAN network without wire over Mobile, Laptop with seamless Roaming without any wire connectivity. It is LAN technology which is used to connect Home, Campus, Building and Corporate network. But sometime we face connectivity issues with WiFi network. Some time Access Points also giving some indications by its LED status but we didn’t understand. Here we will discuss the how to troubleshoot such issues.
Here I am sharing 5 Practical things for Wi-Fi which cover all procedure from AP association to user level Troubleshooting which can be consider as user quick guide.
1.WLC, WAP and Client Association
Step 1 Make sure that the Wireless LAN controller is connected to the network.
- Make sure that access points have Layer 3 connectivity to the Wireless LAN controller Management and AP-Manager Interface.
- Configure the switch to which your access point is to attach.
- Make sure DHCP is enabled on the network. The access point must receive its IP address through DHCP.
- CAPWAP UDP ports must not be blocked in the network.
- The access point must be able to find the IP address of the controller. This can be accomplished using DHCP, DNS, or IP subnet broadcast.
Step 2 Apply power to the access point:
- The access point is 802.3af (15.4 W) compliant and can be powered by any 802.3af-compliant device.
- As the access point attempts to connect to the controller, the LEDs cycle through a green, red, and amber sequence, which can take up to 5 minutes.
Note If the access point remains in this mode for more than five minutes, the access point is unable to find the Master Cisco wireless LAN controller. Check the connection between the access point and the Cisco wireless LAN controller and be sure that they are on the same subnet.
- If the access point shuts down, check the power source.
- After the access point finds the Cisco wireless LAN controller, it attempts to download the new operating system code if the access point code version differs from the Cisco wireless LAN controller code version. While this is happening, the Status LED blinks dark blue.
- If the operating system download is successful, the access point reboots.
Step 3 Configure the access point if required. Use the controller CLI, controller GUI.
Step 4 If the pre-installation configuration is successful, the Status LED is green indicating normal operation. Disconnect the access point and mount it at the location at which you intend to deploy it on the wireless network.
Step 5 If your access point does not indicate normal operation, turn it off and repeat the pre-installation configuration.
(Reference: WWW.Cisco.com).
2. Wireless LAP LED Status Indications
Once access point connected with Network and WLC then its start registering process. All Access point start blinking their LED during this registration and every Light Wright Access Point ( LAP) LED blinking status as an Indication of the Current status of AP registration.
(Reference: WWW.Cisco.com).
3. The Controller Discovery Process
Access points must be discovered by a controller before they can become an active part of the network. The access point supports these controller discovery processes:
- Layer 3 CAPWAP discovery—Can occur on different subnets than the access point and uses IP addresses and UDP packets rather than MAC addresses used by Layer 2 discovery.
- DHCP server discovery—This feature uses DHCP option 43 to provide controller IP addresses to the access points. Cisco switches support a DHCP server option that is typically used for this capability.
- DNS discovery—The access point can discover controllers through your domain name server (DNS). For the access point to do so, you must configure your DNS to return controller IP addresses in response to CISCO-CAPWAP-CONTROLLER.localdomain, where localdomain is the access point domain name. Configuring the CISCO-CAPWAP-CONTROLLER provides backwards compatibility in an existing customer deployment. When an access point receives an IP address and DNS information from a DHCP server, it contacts the DNS to resolve CISCO-CAPWAP-CONTROLLER.localdomain. When the DNS sends a list of controller IP addresses, the access point sends discovery requests to the controllers.
4. Configuration Issues
- SSID Mismatch
- Security Mismatch
- Disabled WLAN
- Unsupported Data-Rates
- Disabled Clients
- 1.SSIDMismatchAlways cross validate all SSID and other configuration with LLD and configuration document
• Make Ensure that the SSID (Service Set Identifier) settings are consistent across all access points and wireless devices as per network requirement and design.
• Implement standardized naming conventions and guidelines for SSID configuration.
• Communicate the correct SSID to users and provide instructions on how to connect to the network.2. Security Mismatch• Evaluate the current security protocols and encryption methods in use.
• Implement strong security process and protocol, such as WPA2-PSK (Wi-Fi Protected Access 2 – Pre-Shared Key) or WPA3 (if supported).
• Frequently update and patch firmware and software to address security vulnerabilities.
• Educate users about the importance of protected Wi-Fi connections and the risks associated with using unsafe networks.3. Disabled WLAN• Explore & Inspect the cause of the disabled WLAN and restore functionality promptly.
• Implement monitoring systems to detect and alert when the WLAN becomes disabled.
• Develop contingency plans for temporary outages, such as utilizing alternative network connections or providing backup access points.
• Establish protocols for prompt response and resolution of WLAN outages.4. Unsupported Data Rates• Perform an audit of the wireless devices and their supported data rates.
• Upgrade or replace devices that do not support the required data rates.
• Adjust the wireless network settings to accommodate the supported data rates of the devices in use.
• Regularly evaluate and update the network infrastructure to support the latest industry standards and data rates.5. Disabled Clients
• Analysis the reasons for disabled clients, such as device settings, software conflicts, or connectivity issues or any hardware issue etc.
• Provide clear instructions to users on how to troubleshoot and enable their Wi-Fi connections.
• Offer technical support and assistance to users experiencing disabled Wi-Fi connections.
• Implement monitoring systems to identify disabled clients and proactively address the issues.
5. DHCP/ IP address problems
Here are the reasons and steps to resolve these issues:
- If the type of authentication configured is one of Layer 2 security solutions, such as 802.1x or WPA, the client must successfully authenticate to obtain a valid IP address. First check if the client is successfully authenticated.
Note: An exception is if the client is configured for Layer 3 security solutions, such as web authentication, or the web passthrough client is assigned an IP address before authentication.
- Each WLAN defined on the WLC is mapped to a dynamic interface of the WLC, which is configured with a VLAN that belongs to a unique subnet. Clients that associate to this WLAN are assigned IP addresses from the interface subnet of the VLAN. Check if the IP subnet and gateway of this WLAN are defined on the DHCP server for the client to obtain an IP address on this subnet. Refer to the documentation of the appropriate vendor to configure the DHCP server.
Note: As a prerequisite, check whether the DHCP server is reachable from the WLC and if the DHCP service is turned on.
- Make sure that the IP address of the DHCP server is defined correctly in the interface of the WLC that is mapped to the WLAN. In order to check this, click the Controller menu in the GUI. Click the Interfaces menu on the left-hand side, and check the DHCP server field. On the same page, check that the interface is mapped to a physical port that is up and active. In order to troubleshoot DHCP related issues, use the commands debug DHCP packet enable and debug dhcp message enable on the WLC.
Note: You can also configure WLC as a DHCP server. For more information on how to configure the DHCP sever on the WLC.
- WLC usually connects to the wired network through a switch. Check if switch ports that are connected to the WLC and the DHCP server are configured as trunk and that the appropriate VLANs are allowed on those ports. For more information on how to configure the Cisco switches.
- Static clients are not allowed to associate to the WLAN if the DHCP Address. Assignment field is enabled for the WLAN. This option necessitates that all clients that associate to this WLAN must obtain IP addresses through DHCP. In order to check if this option is enabled, click the WLANs menu in the WLC GUI. A list of WLANs configured on the WLC displays. Click the appropriate WLAN. Go to the Advanced tab and locate the DHCP Address Assignment field.
- Some DHCP servers, such as a Cisco PIX firewall, do not support DHCP relay services. They accept only broadcast DHCP packets, not any unicast packets from a DHCP relay agent, so ensure that the DHCP clients are directly connected to the interface on which the server is enabled.
Note: Check the appropriate vendor document for DHCP relay support.
(Reference: WWW.Cisco.com)
Conclusion
Every organization has their own network requirement and design and above mentioned all process are standard process and procedure to implement and troubleshoot Wi-Fi issue.
But the risk and issues may differ based on your organization’s network infrastructure, policies, and requirements. So, always troubleshoot your network issues based on your network requirement and design.
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