In summary:
- Boot
- Discovery
- Join
- Code Current? No? Get new code and reboot
- Get Configuration
- Run
WLC Discovery
Methods of WLC discovery including:
- Broadcast if WLC is on same VLAN as AP
- Flash memory i.e. the AP remembers the last WLC it connected to
- DHCP specifically option 43 – IP address of WLC
- DNS looks for hostname CISCO-CAPWAP-CONTROLLER
Example configuration for Option 43 on a router:
ip dhcp pool vlan20
network 172.16.20.0 255.255.255.0
dns-server 172.16.20.1
default-router 172.16.20.1
option 43 hex f104.ac10.0a05
f104.ac10.0a05 is not a MAC address – it is a TLV (Type, Length Value)
f1 = data type
04 = 4 bytes of data
ac10.0a05 = 172.16.10.5 in hex.
Order of Precedence
- IP address of first WLC (if configured)
- IP address of secondary WLC (if configured)
- IP address of tertiary WLC (if configured)
- IP address of master WLC (if configured)
- Least busy WLC.
The Join Process
Two channels between the WLC and the AP.
- Control Channel – DTLS (encryption) UDP 5245. Responsible for code upgrades, configuration and heartbeats
- Client Data – UDP 5247
