Batumi:
Here is a link: http://tiny.cc/34ohcw that shows supported discovery mechanisms.
The question in your picture is a bit old. Layer 2 discovery is very old and no longer supported since a while. Only old versions have layer 2 discovery mode (you can choose to use layer 2 or layer 3 in old versions). current versions all have layer 3 discovery and you can not change that.
The process (in layer 3 discovery)is the following:
- AP boots up and requests an IP address.
- AP tries to discover WLC by the means mentioned in the above link. (your question only metnions broadcast discovery request method it seems but it is not the only one).
- WLCs that receive the discovery requests will reply with discovery response to the AP.
- AP chooses one of the WLCs it discovered. your question mentions it will choose the WLC with least number of APs associated. this is only correct if all WLCs have same importance to the AP. but if the AP is configured for WLC IP address statically this option will be taken anyway. If no static WLC but one of the WLCs discovered is a master WLC this option then will be taken. If none of the above and the AP was joining one of the discovered WLCs before and it is still remembering it will probably (saying probably because no one confirmed this from Cisco AFAIK) join that WLC.
- After an AP decides what WLC to join it sends a unicast packet (join request) to the WLC AP MANAGER IP address. (AP manager IP address is included in discovery response message the WLC sent to the AP in discovery response message mentioned above).
- The WLC replies with a join response, a TLS tunnel created between WLC and AP and the data start communicating (sending image if different between WLC and AP or sending the config from WLC to the AP).
I hope this is clear to you.
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