What Are the Differences Between APs' Layer 2 and Layer 3 Access to ACs?
In Layer 2 access mode, an AP broadcasts a probe frame to discover ACs. In Layer 3 access mode, an AP discovers ACs using DHCP Option 43 or DNS. When Option 43 is used, an AP obtains an AC's IP address when the AP obtains its own IP address. Then the AP sends a unicast probe frame to the AC to discover the AC. When DNS is used, an AP obtains its own IP address, the DNS server's IP address, and AC's domain name. Then the AP sends a domain name resolution request to the DNS server. After the DNS server resolves the AC's IP address based on the domain name, the AP can send a unicast packet to the AC to discover the AC.