An experience case where APs in a certain site fail to go online after registration through the S5560 switch

AC-S5560 switch-AP, Layer 2 registration

Feedback from a certain site indicates that the AP cannot go online after registering with the AC. After checking the version and license, there is no problem, and the AP can also obtain an IP address through DHCP normally. There is no problem with the connectivity between AC and AP.

1)      The AP cannot be registered to the AC. Check the version and license according to the conventional thinking. If there is no problem with the AP AC connectivity, you need to turn on the debug switch to analyze the registration process.

<ac>debug wlan capwap all all

After the debugging switch is turned on, there is no debug information on the AC

2)      Turn on the debug switch on the AP to analyze the AP registration process

<ap> debug wlan capwap all

The debugging information printed by the AP shows that the AP broadcasts a discovery registration request, but does not receive a response from the AC.

3)      Analysis of suspicious points: AC and AP ping packet test is ok, indicating that there is no problem with the link. Theoretically, the broadcast message of the AP can be delivered to the AC normally. However, according to the debug information of the AC, the broadcast registration request has not been received on the AC., indicating that the broadcast registration request message was dropped on the intermediate link.

Considering that the S5560 can also be used as a fusion AC, it is suspected that the S5560 has enabled the fusion AC function and intercepted the registration request message of the AP.

4)      Verification method: debug wlan capwap all all on the S5560, and it is found that the registration request of the received AP is printed on the switch.

5)      Problem location: The broadcast registration request of the AP passes through the S5560. Since the wireless function is enabled on the S5560, the switch does not perform Layer 2 forwarding after receiving the broadcast registration request message but directly sends it to the CPU for processing. Since the AP is not configured on the switch The serial number does not process the registration request, and the message will not be forwarded at Layer 2 again, so the broadcast registration request of the AP cannot be delivered to the AC.

(choose one of the two):

1)      The AP uses option 43 or specifies wlan ac ip to perform unicast registration requests and does not perform broadcast registration requests. Since the destination address of the unicast is not the S5560, the switch does not send the packet to the CPU for processing after receiving the packet, and directly performs Layer 2 transparent transmission.

2)      The switch directly uninstalls the wireless feature package, does not enable the wireless function, and normally releases the registration packets of the AP.