- About This Document
Instructions for Maintenance Engineers
Routine Maintenance
Troubleshooting: Common Information Collection and Fault Diagnostic Commands
Troubleshooting: AC Hardware
Structure Faults
Device Power Module Faults
AC Startup Failures
Optical Module Faults
- General Troubleshooting Procedure
- Information on All Optical Modules Fails to Be Displayed, but Services Are Normal
- The Transmit Power of an Optical Module Is Low
- An Optical Module Does Not Send Optical Signals
- The Transmit Power of an Optical Module Is Normal, but a Large Number of Bit Errors and Packet Loss Exist
Port Faults
PoE (PSE) Faults
Memory Faults
Troubleshooting: AP Hardware
Software Fault Troubleshooting (V200R007 and Later Versions)
STA Experience Fault Troubleshooting
- Troubleshooting: The Network Access Speed Is Slow
- Troubleshooting: The Link Setup Rate Is Low
- Troubleshooting: STA Packet Loss (Wireless Side)
- Troubleshooting: A STA Fails to Ping the Gateway (Wired Packets Are Lost)
- Troubleshooting: Received Signal Strength of a STA Is Weak
- Troubleshooting: A STA Cannot Search for Wi-Fi Signals
- Troubleshooting: STAs Cannot Communicate with Each Other
- Troubleshooting: STA Roaming Fails
- Troubleshooting: Signal Interference Occurs
- Troubleshooting: AI Roaming Does Not Take Effect
AP Joining Fault Troubleshooting
STA Access Authentication Fault Troubleshooting
- Troubleshooting: A STA Fails to Connect to the WLAN
- Troubleshooting: A STA Goes Offline Unexpectedly
- Troubleshooting: A STA Fails to Obtain an IP Address
- Troubleshooting: 802.1X Authentication Failures
- Troubleshooting: HTTP-based External Portal Authentication Failures
- Troubleshooting: Failures in External Portal Authentication Using the Portal Protocol
- Troubleshooting: Portal Redirection Failures
- Troubleshooting: Built-in Portal LDAP or AD Authentication Failures
- Troubleshooting: Failure to Access the Built-in Portal Page
- Troubleshooting: Administrators' AAA Authentication Issues
Device Upgrade Fault Troubleshooting
Device Management Fault Troubleshooting
Reliability Fault Troubleshooting
- Troubleshooting: Link Switchover or Revertive Switchover Occurs
- Troubleshooting: AP Does Not Switch Links In a Timely Manner
- Troubleshooting: AP Selects the Active AC Incorrectly
- Troubleshooting: Dual Links Cannot Be Set Up
- Troubleshooting: HSB Between Two Links Becomes Ineffective
- Troubleshooting: VRRP HSB Becomes Ineffective
- Troubleshooting: Wireless Configuration Synchronization Fails
WLAN Service Fault Troubleshooting
Cloud Management Fault Troubleshooting
- Troubleshooting: A Cloud AP or AC Fails to Go Online
- Troubleshooting: A Cloud AP Fails to Be Upgraded
- Troubleshooting: Cloud APs Fail to Be Calibrated
- Troubleshooting: STAs Fail to Roam Between Cloud APs
- Troubleshooting: Configurations Fail to Be Delivered to Cloud APs
- Troubleshooting: A STA Receives Weak Signals (Cloud AP Scenario)
- Troubleshooting: Signal Interference Occurs (Cloud AP Scenario)
Typical Troubleshooting Cases
Hardware
Software
- Wired Users Can Connect to the Printer but Wireless Users Cannot11
- Revertive Switchover Does not Take Effect
- Wireless Configuration Synchronization Does Not Take Effect
- 802.1X Authentication Failed When the AC Is Connected to the Agile Controller-Campus Server
- Some STAs Fail 802.1X Authentication
- After a STA Successfully Connects to the SSID and Opens a Browser, the Portal Authentication Page Cannot Be Displayed
- An Exception Occurs During the AP5030DN Upgrade and Mode Switching
- Built-in Portal Authentication Failed
- How Do I Customize the Disclaimer Page for Built-in Portal Authentication?
- Some STAs Cannot Connect to the Wi-Fi Network Due to Radar Interference
- The Containment Effect of WIDS Is Poor
Common WLAN Delivery Cases
- Improper Transmit Power Planning
- Improper Channel Planning
- Dense or Sparse Installation of APs
- Obstacles Around Co-Located APs
- Interference in the Installation Environment
- Incorrect Antenna Selection
- Incorrect Installation Direction of Antennas
- Insufficient Antenna Power
- Uninstallation of an RF Load on a Radio Port
- Poor Quality or Improper Installation of Network Cables and Insufficient Optical Fiber Power
- Improper Grounding of Devices
- Lack of Dust-Proof Measures in the Device Installation Environment
- Lightning Strike Due to a Lack of Surge Protectors
- Lack of Waterproof Processing for APs
- Lack of Heat Dissipation Design During AP Installation
- Insufficient Power Supply to APs
- Current Leakage in the Installation Environment
- Wall Plate APs Are Not Installed on Walls
- Incorrect PoE Injector Installation Position
TechNotes: How an AP Joins an AC and Troubleshooting Any Join Failures
- Overview
- Before You Start
- AP Join Process
Configuring an AP to Go Online
Common Causes and Troubleshooting Methods for APs' Failures to Go Online
- Recommended Troubleshooting Roadmap for APs' Failures to Go Online
- An AP Fails to Start
- The Network Between the AP and AC Fails
- An Error Occurs in Configuring a Static IP Address for an AP
- No IP Address Is Allocated to an AP
- The AC's IP Address Is Not or Incorrectly Specified on an AP
- The CAPWAP Source Interface or Address Is Not Configured on the AC
- An AP Is Not Working in Fit Mode
- The Number of APs Connected to the AC Exceeds the Maximum
- DTLS Negotiation Failed
- The MAC Address and SN of an AP Specified on the AC Are Inconsistent with Those of the AP
- An AP Is Blacklisted
- The Versions of the AP and AC Do Not Match
- The AP Upgrade Fails
- An AP Fails to Initialize the Configuration
- Further Information: How to Configure Basic WLAN Services After APs Go Online
TechNotes: Troubleshooting WLAN Password Issues
- Introduction
- Prerequisites
- Default User Names and Passwords for WLAN ACs and APs
Recovering the Console Password
- Logging In to a Device Using Telnet or STelnet and Changing the Console Password
- Clearing the Console Password in the BIOS Menu and Changing the Console Password
- Changing the Password of a Fit AP on an AC
- Changing the Password of a Fit AP in the Uboot View
- Clearing the Console Port Password in the Uboot View and Changing the Console Password
- Recovering the Password for Bluetooth Serial Port Login After Skipping the Startup Based on the Bluetooth Serial Port Password
- Recovering the Password of an AT
Recovering a Telnet Password
Recovering the BootROM Password
- Related Information: How to Log In to a WLAN AC or AP
TechNotes: AP Mode Switching - Overview, Configuration Examples, and Troubleshooting
- Introduction
- Understanding Modes Supported by APs
- Understanding APs Support Mode Switching
- How to Check the Current Working Mode of an AP
- How to Switch the Working Mode of an AP
AP Mode Switching Examples
- Example for Switching the AP Working Mode by One Click
- Example for Switching a Fit AP with Factory Defaults to the Fat Mode by One Click
- Example for Switching a Fit AP to the Fat Mode Using SFTP
- Example for Switching a Fit AP to the Fat Mode Using FTP
- Example for Switching an Online Fit AP to the Fat Mode Through the AC
- Example for Switching a Fit AP to the Fat Mode Using Uboot
- Troubleshooting
- Related Information: How to Use the AP After Its Mode Is Switched
TechNotes: VLAN Deployment Guide for WLAN
TechNotes: WLAN Performance Test Guide
Help Topic: WLAN Common Configuration Errors
User Experience Issues
STAs Cannot Obtain IP Addresses
Layer 3 Roaming Issues
STA Access Issues
APs Cannot Go Online
Reliability Issues
- The Active and Standby ACs Have Different Configurations
- Configurations Delivered to APs Do Not Take Effect
- A Network Fault Occurs When Multiple Backup Modes Are Configured
- HSB Is Configured Incorrectly
- A Revertive Switchover Error Occurs
- Multiple Masters Coexist in a VRRP Group
- The VRRP Group Status Changes Frequently
NAC Access Issues
Device Management Issues
Help Topic: WLAN Network Optimization
FAQ
Protocols and Basic Concepts
- What Are the Differences Between 802.11a/b/g/n/ac/ac Wave2/ax Standards?
- What Are Interference Sources on WLANs? How Is the Interference Strength?
- What Are WLAN Reliability Features?
- What Are the Relationship and Difference Between WLAN and Wi-Fi?
- What Are MIMO, MRC, Beamforming, STBC, and Spatial Multiplexing?
- What Are the Differences Between H20 and H40, How Is the 11n 40 MHz Channel Is Partitioned, and What Are the Meanings of Plus and Minus?
- What Is the WLAN Coverage Range?
- What Are the ESS, BSS, and SSID?
- What Is the Working Process of 802.11n Short GI?
- What Are the Advantages and Disadvantages of FHSS and DSSS?
- Is the WLAN Rate the Upstream or Downstream Rate?
- What Are the Physical Rate, Theoretical Rate, and Actual Rate in the 802.11 Standard?
- What Is the Relationship Between WMM and 802.11e?
- What Are the Implementations of 802.11n Frame Aggregation Technologies, MSDU and MPDU?
- Does an AP Listen to and Send Frames over One Channel?
- How Does a STA Synchronize the Channel When the Associated AP Switches to Another Channel?
- What Are Radar Channels? How Do They Affect Other Channels?
- What Is EIRP?
- Can an AP (Single Radio) with Different SSIDs Work at Different Channels?
- How Does an AP Adjust the Rate?
- How Do I Query the Power of an AP on an AC?
- What Are the Maximum Link Setup Rate, Real-time Packet Sending Rate, and Bandwidth of a STA?
- Description of Common Logs on ACs
- What Are System Users of WLAN devices?
Product FAQs
Networking
- What Are the Differences in AP-side Switch Interface Configuration and Intermediate Switch Configuration in Direct and Tunnel Forwarding Modes?
- What Are Advantages and Disadvantages of Direct Forwarding and Tunnel Forwarding?
- What Cautions Should Be Taken When Configuring Option 43 on the AC?
- What Cautions Should Be Taken When Configuring the Layer 2 Access Network Between APs and the Gateway on a WLAN Network?
- What Are the Differences in APs' Layer 2 and Layer 3 Access to ACs?
- What Is the Registration Procedure When a Fit AP and an AC Are Connected Directly or over a Layer 2 Network?
- What Is the Registration (in DNS Mode) Procedure When an AC and a Fit AP Are Connected Across a Layer 3 Network?
- What Is the Registration (in Option 43 Mode) Procedure When an AC and a Fit AP Are Connected Across a Layer 3 Network?
- Can a Central AP Be Connected to a Common AP and Function as a Switch?
- Can a Central AP Be Connected to RUs Through a Switch?
- What Are Precautions for Deploying a Central AP?
- What Are Precautions for Deploying the WLAN Standby Plan?
- What Are Precautions for Deploying the WLAN Hot Standby Plan?
- After VRRP HSB Is Deployed on ACs, the AP Status on the Active AC Is Normal. Is the AP Status on the Standby AC Automatically Backed Up?
- Does the Virtual IP Address in a VRRP HSB Scenario Exist?
- In a VRRP Scenario, Advertisement Packets Cannot Be Forwarded Between the Active and Standby ACs, and the Standby AC Fails to Become the Active AC. Why?
- VRRP Is Configured on the Downlinks of ACs but Not on the Uplinks of ACs. If a Downlink Fails, Will User Services Be Interrupted? If So, Can the Services Be Recovered?
- In a VRRP HSB Scenario, When the Active AC Is Restarted, an Active/Standby Switchover Is Triggered Normally. After the Original Active AC Is Restarted, All APs Become Faulty and Services Are Interrupted. Why?
- In a VRRP HSB Scenario, Portal Authentication Fails. Why?
- What Is the Difference Between Direct Forwarding and Tunnel Forwarding During STA Login?
- Do I Need to Create a Service VLAN on an AC When the AC Is Deployed in Bypass Mode and Service Data Is Forwarded in Direct Mode?
WLAN Network Planning and Optimization FAQs
DHCP
- Can a DHCP Server (BAS, High-End Router, or High-End Switch) Allocate IP Addresses to APs?
- Why Do IP Address Conflicts Occur on an AC? What Measures Should Be Taken in This Case?
- Why Does an AP Restart Repeatedly or Its IP Address Change Frequently?
- How Can I Know Whether an AP Has Obtained an IP Address?
- What Measures Should Be Taken When an AP Fails to Obtain an IP Address Using DHCP?
- What Measures Should Be Taken When an AC Fails to Respond to the Discovery Packet Sent by an AP After the AP Obtains an IP Address?
- How Do APs Obtain the AC IP Address? What Is the Recommended Method?
- How Can I Configure an AC as a DNS Server?
Access Authentication
- What Is Centralized Authentication?
- Does the Device Support NAC Access Authentication for IPv6 Users?
- Does the Device Support the Portal 2.0 Protocol of CMCC?
- Why Is the Portal Login Page Not Displayed Automatically After a Client Connects to the Wi-Fi?
- Why the Administrator Cannot Log In to the Device After the Authentication Mode in the Default Authentication Scheme Is Set to Non-authentication in an Anonymous Login Scenario?
- Which Terminal Types Can Be Identified Using the Terminal Type Identification Function? How Can I View Information About the Identified Terminals?
- Does a STA Blacklist Force STAs to Go Offline?
- How Do I Perform Configurations to Free Portal Users from Reauthentication When Portal Authentication and Roaming Have Been Enabled and Wi-Fi Coverage Holes Exist?
- iPhones Running iOS6.0 or Later Fail to Associate with a WLAN Using Portal Authentication. iPads Are Disconnected Immediately After Being Authenticated. How Do I Solve These Problems?
- In Portal Authentication, Why Does the Redirected Authentication Page Fail to Be Triggered on Some Websites (Such as Google and Baidu)?
- How Can I Check that a STA Successfully Connects to the WLAN?
- How Can I View Historical Online and Offline Records of an STA on the AC?
- How Can I Collect Statistics on User Service Interruption?
- How Can I Collect Statistics on APs' Failures to Get Online?
- How Do I Configure an AP to Go Online Using a Static IP Address?
- Why Cannot Users Associate with APs When WPA-PSK Authentication Is Used?
- Why Cannot STA Associate with an AP When WEP Authentication Is Used?
- What Are Advantages and Disadvantages of WAPI Authentication?
- What Is the Difference Between Portal Authentication and 802.1X Authentication?
- What Authentication Protocols Are Supported During STA Login? Which One Is Recommended and Why?
- How Can I View Device Authentication Specifications?
- Is VLAN-based Authorization Supported by MAC Address Authentication and Portal Authentication?
- What RADIUS Attributes Need to Be Delivered for VLAN-based Authorization?
- What Are the Restrictions of an Authorization ACL?
- Which 802.1X Authentication Modes Are Supported by the Device?
- What Are the Differences Between Fast Roaming and Non-Fast Roaming?
- Does the Device Support Built-in Portal Page Customization? What Are the Requirements for Page Elements?
- How Do I Use Redirection Parameters?
- Does the AD/LDAP Base DN Support Chinese Characters?
- How Do Different Authentication Modes Support AD/LDAP Authentication?
STA
- Why Is the Channel Switching Sometimes Slow During STA Roaming? How Can I Improve the Roaming Sensitivity of a Wireless NIC?
- Does the STA Need to Be Reauthenticated or Re-logged In During STA Roaming? Do the STA's Subnet Properties (Including the IP Address, Home VLAN, ACL, and Priority) Change?
- How Can I Separate Two STAs that Connect to the Same AP and SSID?
- STA Receives Strong Signals from an AP, But the Network Speed Is Slow. How Can I Locate the Problem?
- Why Is the Association Rate Displayed on Wireless Terminals Low?
- Why Does a STA Fail to Associate with an AP When WEP and TKIP Encryption Is Configured in 802.11n Mode?
- The Laptop Uses the 802.11b/g NIC. How Can I Associate It with a 802.11n AP?
- I Bought a Wi-Fi NIC. The Vendor States It Is an 802.11a/b/g/n Network Card, But Why Did I Fail to Search 5 GHz AP Signals (AP Works on Channel 149) Using This NIC?
- Why Did STA Fail to Search 802.11n Signals After the AP Is Enabled with 802.11n?
- Does BT Download Occupy High Bandwidth and Reduce WLAN Efficiency?
- Does an Online 802.11b/g Terminal Affect the Rate of an Online 802.11n Terminal?
- After iPhones or iPads Running Some Versions (Such as iOS 7.0.4) Associate with an AP, No Signal Bar Is Displayed. How Do I Solve the Problem?
- An Apple Terminal Goes Offline After the Screen Is Locked. When the Screen Is Turned On, the Terminal Does Not Automatically Associate with the WLAN. Why?
- Android and Windows Terminals Can Properly Access the Web Server on the Intranet but iOS Terminals Cannot. Why?
- In Portal Authentication Mode, iPhones in iOS 6.0 or Higher Versions Cannot Associate with APs, and iPads Are Disconnected Immediately After Passing Authentication. How Can I Solve This Problem?
- iPhones Cannot Obtain IP Addresses Whereas Other Terminals Can. How Can I Solve This Problem?
- Why Roaming in Direct Forwarding Mode Fails After IP Source Guard (IPSG) Is Configured on a GE Port?
- What Should I Do If iTunes Exits Unexpectedly When User Terminals Obtain Service Information Through iTunes?
- How Do I Configure Multicast Packet Suppression to Reduce Impact of a Large Number of Low-Rate Multicast Packets on the Wireless Network?
- License
Others
- What Is the Function of a WLAN AC Source or CAPWAP Source?
- Why Is Displayed Radio Member Traffic Information Inaccurate?
- What Are the Requirements for a Radio to Join a Load Balancing Group?
- How Is a BSSID Generated? (V200R005C10 and Earlier Versions)
- What Are the Timeout Mechanism of CAPWAP Link and Timeout Period Calculation?
- Does Huawei Provide a Comprehensive Solution for Managing APs of Different Manufacturers?
- What Is the Function of the WLAN QoS Profile?
- What Is the Difference Between the WMM Mandatory Switch and WMM Function Switch?
- Is the Scanned Air Port MAC Address of the SSID Sent by Huawei APs in Multicast Mode the Same as the AP's MAC Address?
- Why Does a Manually Configured Radio Channel Not Take Effect?
- After an 802.3at AP in V200R008C10 Is Connected to a Switch in V200R001, V200R002, or V200R003, the AP Works in 802.3af Mode. How Can I Enable the AP to Work in 802.3at Mode?
- Why No Data Is Displayed on the AP Spectrum Chart?
- What Are the Differences Between Wi-Fi Tag Location and Terminal Location?
- Do Channel and Power Changes Cause Service Interruption on STAs During Automatic Radio Calibration?
- How Do I Check the MAC Address of a WLAN Device?
- Can a Root Node on a WDS Network Send Signals of WDS VAPs and Service VAPs at the Same Time?
- How Do I Save Logs to the Log System?
- How Can I Obtain the Paibo terminal location Plug-in and Related Documentation?
- How Can I Obtain the Surfilter terminal location Plug-in and Related Documentation?
- What Are the Differences Between CA, Local, and Self-Signed Certificates?
- Which Certificate Formats Are Supported?
- How Do I Manually Import Certificates and an RSA Key Pair?
- How Do I Set Parameters Such as the CIR and CBS When Configuring Rate Limiting?
- What Is Configuration Rollback? What Is Version Rollback?
Software Fault Troubleshooting (V200R005 and Earlier Versions)
Troubleshooting: AP Fails to Go Online
Troubleshooting: AP Upgrade Fails
Troubleshooting: User Experience Issues
Troubleshooting: STA Fails to Go Online
- Common Causes
- Process Tracing
- STA Process Tracing on the AC
- Association Failure
- Portal Authentication Failure
- 802.1x Authentication
- MAC Address Authentication Failure
- STA Fails to Obtain an IP Address
- STA Services Are Interrupted
- Why Signals Are Unavailable for a STA?
- Collecting STA Online Information
- Troubleshooting Cases
Troubleshooting: STA Roaming Errors Occur
Troubleshooting: Reliability Issues
Troubleshooting: WDS Link Failure
Troubleshooting: Mesh Link Failure
Software Fault Troubleshooting (V200R006)
Troubleshooting: AP Fails to Go Online
Troubleshooting: AP Upgrade Fails
Troubleshooting: User Experience Issues
Troubleshooting: STA Fails to Go Online
Troubleshooting: STA Roaming Errors Occur
Troubleshooting: Reliability Issues
Troubleshooting: WDS Link Failure
Troubleshooting: Mesh Link Failure
Troubleshooting: Spectrum Analysis Failure
Troubleshooting: WLAN Location Failure
- Troubleshooting: Memory Failure