AP注册不上线（现网中存在其它厂商的控制器）
在网络中存在两台控制器MSG360(192.168.0.223)和TP-LINK AC(192.168.0.253)
AP是华三的WAP712C

1、排错思路：
1）DHCP是在MSG360上，首先在AP查看是否能获取地址
AP可以获取地址
此处配置没有记录

2）在AP上查看capwap debug信息
从AP的debug信息可以看出，虽然MSG360(192.168.0.223)有发送discovery response过来，但是AP还是选择了TP-LINK AC(192.168.0.253)作为控制器进行注册，因为是TP-LINK的控制器，AP注册不上去，所以AP报错提示：Failed to load SSL certificates,uiAPID = 1. 然后进入Enter Sulking state，后变成 Enter Idle state。

WAP712C的capwap debug信息：

*Jan  1 00:04:42:931 2014 H3C CWC/7/RCV_PKT: Received discovery response with SeqNum 0 from AC at 192.168.0.223:5246.
*Jan  1 00:04:42:931 2014 H3C CWC/7/RCV_PKT: Verbose info for discovery response from AC 192.168.0.223:5246, length=128.00 10 02 00 00 00 00 00 00 00 00 02 00 00 73 0000 01 00 31 00 00 FF FF 00 02 00 14 00 02 00 0200 00 00 00 00 04 00 04 00 00 00 41 00 00 00 0000 05 00 03 39 39 00 00 00 00 00 01 00 00 06 0440 A9 2E 3B A8 00 04 00 12 57 69 72 65 6C 65 7373 43 6F 6E 74 72 6F 6C 6C 65 72 04 18 00 05 0100 00 00 0A 04 18 00 05 02 00 00 00 0D 00 25 000F 00 00 63 A2 00 80 00 01 04 00 00 00 02 00 01
.
*Jan  1 00:04:42:932 2014 H3C CWC/7/RCV_PKT: Received discovery response with SeqNum 0 from AC at 192.168.0.223:5246.
*Jan  1 00:04:42:932 2014 H3C CWC/7/RCV_PKT: Verbose info for discovery response from AC 192.168.0.223:5246, length=128.00 10 02 00 00 00 00 00 00 00 00 02 00 00 73 0000 01 00 31 00 00 FF FF 00 02 00 14 00 02 00 0200 00 00 00 00 04 00 04 00 00 00 41 00 00 00 0000 05 00 03 39 39 00 00 00 00 00 01 00 00 06 0440 A9 2E 3B A8 00 04 00 12 57 69 72 65 6C 65 7373 43 6F 6E 74 72 6F 6C 6C 65 72 04 18 00 05 0100 00 00 0A 04 18 00 05 02 00 00 00 0D 00 25 000F 00 00 63 A2 00 80 00 01 04 00 00 00 02 00 01
.
*Jan  1 00:04:44:932 2014 H3C CWC/7/TMR: Discovery Interval timer expired.uiAPID = 1.
*Jan  1 00:04:44:933 2014 H3C CWC/7/EVENT: Discovered AC by method of IPv4 broadcast successfully.
*Jan  1 00:04:44:933 2014 H3C CWC/7/EVENT: AP selected AC IP 192.168.0.253 Priority 0 successfully.
*Jan  1 00:04:44:935 2014 H3C CWC/7/ERROR: Failed to load SSL certificates,uiAPID = 1.
*Jan  1 00:04:44:935 2014 H3C CWC/7/FSM: Enter Sulking state.
*Jan  1 00:04:46:932 2014 H3C CWC/7/TMR: Silent Interval timer expired.
*Jan  1 00:04:46:933 2014 H3C CWC/7/FSM: Enter Idle state.
*Jan  1 00:04:46:933 2014 H3C CWC/7/EVENT: Start ipv4 dhcp opt43 discover.
*Jan  1 00:04:46:933 2014 H3C CWC/7/EVENT: Start ipv4 broadcast discover.
*Jan  1 00:04:46:942 2014 H3C CWC/7/EVENT: Open capwap client udp port:50048
*Jan  1 00:04:46:942 2014 H3C CWC/7/FSM: Enter Discovery state.
*Jan  1 00:04:46:943 2014 H3C CWC/7/EVENT: Fill discover req.wtu=1.model=WAP712C.wt drv info:[].subslot=0.licensetype=1.ret=0x40010001.
*Jan  1 00:04:46:943 2014 H3C CWC/7/EVENT: Fill discover req.ap=1.model=WAP712C.licensetype=1.carry wt info is unnecessary.
*Jan  1 00:04:46:944 2014 H3C CWC/7/SND_PKT: Sent discovery request with SeqNum 0 to AC 255.255.255.255:5246.
*Jan  1 00:04:46:944 2014 H3C CWC/7/SND_PKT: Verbose info for discovery request sent to AC 255.255.255.255:5246, length=155.00 10 02 00 00 00 00 00 00 00 00 01 00 00 8E 0000 14 00 01 00 00 26 00 3A 00 00 63 A2 00 00 0007 57 41 50 37 31 32 43 00 01 00 14 32 31 39 3830 31 41 30 58 35 39 31 38 31 47 30 30 30 4B 3100 03 00 05 56 65 72 2E 41 00 04 00 06 48 BD 3D63 AD 60 00 27 00 28 04 04 01 01 00 00 00 00 63A2 00 00 00 01 41 00 00 63 A2 00 01 00 05 52 3232 32 31 00 00 63 A2 00 02 00 04 37 2E 31 31 0029 00 01 0E 00 2C 00 01 02 04 18 00 05 01 00 0000 0A 04 18 00 05 02 00 00 00 0D
.

2、解决方案：

在网络中存在两个AC的情况，可以在MSG360上配置二次AC发现功能

1）二次AC发现功能作用：

二次发现AC功能用于向AP提供建立CAPWAP隧道的目的AC的IP地址。开启该功能后，AC发送的Discovery response报文中会携带CAPWAP Control IP Address消息元素，AP收到Discovery response报文后，将向消息元素中的IP地址发送Discovery request报文，达到二次发现AC的目的。

2）直接在AC1全局模式下配置：

system-view
wlan global-configuration
control-address enable    #<==默认情况下二次发现AC功能处于关闭状态