【Typical Case】Troubleshooting AP Online Failure in the Ruijie WLAN Public Network Scenario

Keywords:

AP failed to go online, AP went online on a public network
Networking Diagram
An AC isdeployed at the headquarters of a customer, and an AP is deployed at a remotebranch of the customer. An IPsec VPN tunnel is established between the egressrouters at the headquarters and branch, and the AP communicates with the ACthrough the IPsec VPN.

Symptom
The APpings the AC successfully, but cannot go online on the AC.
Device Model and Firmware

Device Type	Device Model	Firmware Version
Ruijie  WLAN	Ruijie  AP/AC	RGOS  11.9(6)W3B1

Cause Analysis
1. As the AP can ping the AC, it can be confirmedthat network connectivity is not the issue.
2. The customer uses the public network, with packets traversing VPN tunnels. It issuspected that packets become too large after tunnel encapsulation, leading to the discard of CAPWAP packets. Therefore, the CAPWAP MTU needs to be adjusted.

How Can I Modify the MTU Used  for Tunnel Establishment on the AC? Ruijie(config)#ac-controller Ruijie(config-ac)#capwap  ctrl-mtu ? Ruijie(config-ac)#capwap  ctrl-mtu 1300  (range: 1– 1500) Ruijie(config-ac)#end Ruijie#write

However,the AP still fails to go online even when the MTU is changed to 1300.
3. To bring an AP online, it requires a specifiedAC IP address. Typically, DHCP servers provide Option 138 to assign the AC IPaddress. Since the remote branch is located in a home environment, it issuspected that the home router may not support Option 138. Therefore, considermanually assigning the AC IP address on the AP.

Q: How  do I configure a static IP address for an AP in Fit AP mode?      A: To configure a static IP address for an  AP in Fit AP mode   Correct operation:    Reference  command: (Changing this parameter will cause the AP to re-establish a  tunnel.)   (1)  Log in to the AP through the console or Telnet, enter the global  configuration mode (the enable password is apdebug), and configure the static IP address, default route, and  AC IP address.   Ruijie(config)#acip  ipv4 1.1.1.1      Configure  the IP address of the AC.   Ruijie(config)#apip  ipv4 172.16.1.34 255.255.255.0 172.16.1.109   (2)  After a tunnel between the AP and AC is established, log in to the AC to  configure a static IP address for the AP.     Ruijie(config)#ap-config  220e          Ruijie(config-ap)#acip  ipv4 1.1.1.1        Configure  the IP address of the AC.     Ruijie(config-ap)#ip  address 172.16.1.34 255.255.255.0 172.16.1.109    Configure  the IP address, subnet mask, and gateway for the AP. After the configuration  is saved, the AP re-establishes a tunnel. The  two configurations will not be lost after the configurations are saved and  the AP is restarted.    [It is strictly forbidden to  modify the IP address of the fit AP by using the int bvi x and ip add xx  commands. Any configuration changes made this way cannot be saved and will be  lost upon AP restart.]

When the user runs the acip ipv4 (AC IP address) command on the AP to obtain the AC IPaddress, the following notification is displayed:

5. Manually switch the AP to Fit mode, restart it, and verify if it remains in cloud mode. Upon reviewing the AP configurations,WIS Cloud settings are found. It is suspected that the AP has been online onthe WIS Cloud and is still bound to the WIS Cloud. During startup, the fit AP communicates with the WIS Cloud, and automatically switches to the cloud modeafter successful communication.

3.Solution
After the customer logs in to the WIS cloud, unbinds the AP, and switches the AP back to fit mode, the AP successfully goes online.