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3.6.3. CAPWAP

CAPWAP (Control And Provisioning of Wireless Access Points) is the tunnel protocol between lightweight APs and the WLC. Everything flows through this tunnel—control messages, management, and optionally client data.

Traffic TypeUDP PortEncryptionContents
Control5246DTLS (mandatory)AP config, client handoff, management
Data5247DTLS (optional)Client traffic (in Local mode)

What happens when the WLC becomes unreachable: Lightweight APs enter a limited "survivability" mode—existing clients stay connected, but no new clients can join, and you can't make configuration changes. That's why WLC redundancy matters. Some deployments use FlexConnect specifically so branches can survive WLC outages.

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⚠️ Exam Trap: If CAPWAP ports (5246/5247 UDP) are blocked by a firewall between the AP and WLC, the AP can't join the controller. This is a common troubleshooting scenario.