Most APs cannot go online, online APs often go offline and the tunnel status frequently changes

Most APs cannot go online, online APs often go offline and the tunnel status frequently changes

TroubleshootingSteps

(1) Check the network topology, wirelessconfiguration, version, and log.

The version configurations are consistent.

log:

Oct 16 00:24:27: %CAPWAP-5-RETRANS_MAX: (*2)(peer - 47) [172.17.6.30 : 10000] reach maximum retransmit count [5], msg is[configuration update request], seq is [1], elem length is [34].

Oct 16 00:24:27: %CAPWAP-6-PEER_NOTIFY_DOWN: (*2) Peer <172.17.6.30 : 10000 : 5869.6cea.d18d> DOWN, reason<Retransmit MAX>.

The intermediateline may have a fault.

(2) Log on to the failed AP to check the APmode and confirm whether any IP address is obtained. Check whether the large packet can be communicated on the tunnel used for the AP to ping the AC.

Packet loss is rare during AC ping on the AP.The intermediate line mayhave a loop or the broadcast traffic is too large.

(3) Log on to the AC and run the clear counters command to clear theinterface traffic statistics. After show int counters summary is collected for three consecutive times, the broadcast packets at the interconnected interface increases quickly, as shownin the following figure:

(4) Log on to the interconnected core devicesand run the clear counters commandto clear the interface traffic statistics. After show int counters summary is collected for three consecutive times,the following figures are displayed:

A great amount of broadcast packets increaseat the Te1/3/20, indicating that a loop may exist.

(5) After confirming that the deviceconnected to the Te1/3/20 interface is the AP of the access switch, down theTe1/3/20 interface to check whether all the APs under the Te1/3/20 interface goonline one after another and the network is recovered.

(6) Log on to the access switch and enableRLDP. It is found that one interface is in down state. Check connection statusof the associated device. The result shows that the switch is a private switchand has a loop.

Cause

The switch connected to the access switch hasa loop at a single port.

Solution

shutdown the loop interface.

Summary

(1) When a tunnel cannot be established or isestablished repeatedly for some APs, a loop may exist. Even if no loop exists,packet loss is impossible when you ping the AC on the AP.

(2) After a similar fault occurs, check thefault scope and active-standby configuration consistency.

(3) If the load balancing policy isincorrectly configured in VAC, the AP may often go online and offlinefrequently or cannot go online.

(4) In case a loop exists, enable the treegeneration or RLDP function and query the switch logs to check the informationof the failed port having the loop.