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December 9, 2025

Cisco AP Config Snippets (WLC Join, TFTP, IOS)

Work notes for configuring Cisco Wireless APs. Common checks and image load steps.

Check IP and CAPWAP join state

show capwap ip config show capwap client config 

Common join blockers:

  • Bad time/NTP (check controller time or allow time sync on CAPWAP)
  • DHCP Option 43 missing (add controller IP via DHCP or statically set below)
  • Stale controller list (clear it and set manually)

Set static controller(s):

capwap ap controller ip address <WLC-IP-1> capwap ap controller ip address <WLC-IP-2> # optional capwap ap hostname <AP-NAME> # set a friendly hostname 

Clear old controller info:

clear capwap private-config 

Load firmware from TFTP (ROMMON-style)

ap: set IP_ADDR 10.1.128.120 ap: set NETMASK 255.255.255.0 ap: set DEFAULT_ROUTER 10.1.128.1 ap: set TFTP_SERVER 10.1.250.46 ap: set TFTP_FILE ap3g2-k9w8-tar.default ap: tftp_init ap: ether_init ap: flash_init ap: tar -xtract tftp://10.1.250.46/ap3g2-k9w8-tar.default flash: ap: boot 

Bootloader environment (alternate)

uboot>> setenv ipaddr 10.1.128.120 # AP IP uboot>> setenv serverip 10.1.250.46 # TFTP server (your PC) uboot>> setenv netmask 255.255.255.0 setenv gatewayip 10.1.128.1 uboot>> printenv uboot>> tftpboot 0x80000000 ap3g3-k9w8-tar.default uboot>> bootm 0x80000000 

From IOS on the AP

archive download-sw /overwrite /force-reload tftp://10.1.250.46/ap3g3-k9w8-tar.default archive download-sw /overwrite /force-reload tftp://10.1.250.46/AIR-AP1830-K9-8-10-196-0.tar # If you don’t need to force/overwrite: archive download-sw /reload tftp://10.1.250.46/AIR-AP1830-K9-8-10-196-0.tar 

Convert to Lightweight (CAPWAP) from Autonomous

On autonomous IOS (k9w7), point at the recovery/default image:

archive download-sw /force-reload /overwrite tftp://10.1.250.46/ap3g2-k9w8-tar.default 

Factory reset / clear config

write erase delete flash:private-multiple-fs reload 

On some models:

clear capwap private-config reload 

DHCP Option 43 (Cisco controller) quick ref

Option 43 hex for one WLC IP (example 10.1.250.10):
f1:04:0a:01:fa:0a

Multiple controllers: concatenate f1:<len>:<ip1><ip2>... where <len> is total bytes of IP list. Use a DHCP option 43 calculator if unsure.

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