WX3500X两个无线组下的AP不定时掉线

AC旁挂核心，交换机连接AP，终端通过AP接入网络

E2和E3组下的AP不定期掉线，其他AP正常上线.

E2-APXX                        10.100.X.X   Run       12-21 16:06:15

E2-APXX                        10.100.X.X   Run       12-21 16:06:14

E3-AP0XX                       10.100.X.X   Run       12-21 15:16:40

E3-APXX                        10.100.X.X   Run       12-21 15:16:36

E2-APXX                        10.100.X.X   Run       12-21 15:09:43

P1-APXX                        10.100.X.X    Run       12-21 08:36:00

N1-APXX                        10.100.X.X    Run       12-16 18:36:57

M1-APXX                        10.100.X.X     Run       12-16 18:36:56

E2和E3组下的AP不定期掉线，其他AP正常上线

查看AC诊断中的隧道down原因，大部分都是

Failed to retransmit message和Processed join request in Run state

capwap会定时重传，发现重传失败，说明AC与AP之间的链路不稳定。

==== display wlan ap statistics tunnel-down-record  ==== 

AP name                        AP ID  Tunnel down at  Tunnel Down Reason  

E3-APXX                        145    12-22/08:05:53  Failed to retransmit messa

                                                      ge                        

E3-APXX                        133    12-22/07:51:51  Failed to retransmit messa

                                                      ge                       

E2-APXX                        135    12-22/07:46:08  Processed join request in

                                                      Run state                

E3-APXX                        134    12-22/04:26:38  Processed join request in

                                                      Run state                

E2-APXX                        126    12-22/03:18:02  Failed to retransmit messa

经过现场排查发现E2和E3组下的交换机都是在一台接入交换机中。

检查交换机发现有大量的TC报文导致ARP超限速

%Dec 22 10:48:23:381 2022 STP/6/STP_NOTIFIED_TC: Instance 0's port Bridge-Aggregation1 was notified a topology change.

%Dec 22 10:48:26:351 2022 STP/6/STP_NOTIFIED_TC: Instance 0's port Bridge-Aggregation1 was notified a topology change.

%Dec 22 10:48:49:995 2022 STP/6/STP_NOTIFIED_TC: Instance 0's port Bridge-Aggregation1 was notified a topology change.

STP_NOTIFIED_TC，这是远端相连设备通知本设备某接口所在生成树实例或VLAN的拓扑发生变化后产生的TC报文。

===============debug rxtx softcar show slot 1=============== 

ID  Type                RcvPps Rcv_All    DisPkt_All Pps  Dyn Swi Hash Am APps

0   ROOT                0      0          0          300  S   On  SMAC 0 0

1   ISIS                0      0          0          200  D   On  SMAC 8 512

2   ESIS                0      0          0          100  S   On  SMAC 8 512

3   CLNP                0      0          0          100  S   On  SMAC 8 512

…

30  ARP                 1      101020     36686      500  S   On  SMAC 8 4096

31  ARP_REPLY           0      1276       0          500  S   On  SMAC 8 4096

现场TC报文过多导致ARP超限速，导致中间链路不稳定。

现场排除TC报文后正常上线。