The Control and Provisioning of Wireless Access Points (CAPWAP) is a protocol used in split-mac wireless architectures to manage access points (APs) in a centralized manner. It is a lightweight protocol that allows for secure communication between the wireless LAN controller and the APs. CAPWAP is used in wireless networks that employ a centralized controller, and it provides a number of advantages over other management protocols.
In a CAPWAP-enabled wireless network, the APs are split into two logical components: the Control and Provisioning of Wireless Access Points (CAPWAP) protocol and the Access Point Protocol (APP). The CAPWAP protocol is responsible for the centralized management of the network, while the APP handles the data traffic.
Advantages of CAPWAP:
With CAPWAP, adding new APs to a wireless network is a simple process. The administrator can configure the new APs from the centralized controller, and they will automatically join the network.
CAPWAP provides a high level of security, ensuring that all communication between the APs and the controller is encrypted and secure.
How CAPWAP Works:
When an AP is powered on and connected to the network, it sends a discovery request message to the network, looking for a WLC. The AP can use various methods to discover the WLC, including Domain Name System (DNS) resolution, Dynamic Host Configuration Protocol (DHCP) option 43, or a locally stored IP address.
Once the AP discovers the WLC, it sends a join request message to the WLC. The WLC will then send a join response message to the AP, which includes the configuration parameters for the AP, such as the SSIDs and security policies. The AP will then establish a CAPWAP tunnel with the WLC over the UDP port 5246. This tunnel is used to carry all the CAPWAP messages between the AP and the controller.
The CAPWAP protocol has several message types, including Discovery, Join, Configuration, and Data. The Discovery message type is used by the AP to discover the WLC, while the Join message type is used to join the network. The Configuration message type is used to configure the APs, and the Data message type is used to transmit the wireless frames between the AP and the WLC.
Protocol and Port:
CAPWAP operates on the transport layer of the OSI model and uses the User Datagram Protocol (UDP) on port 5246 and 5247 for encrypted and unencrypted traffic respectively. The CAPWAP protocol encapsulates the wireless frames and sends them over the network to the WLC, which de-encapsulates the frames and forwards them to the wired network.
Conclusion
In summary, CAPWAP is a protocol used in split-mac wireless architectures to provide centralized management of APs in a wireless network. It provides a number of advantages, including centralized management, scalability, and security. CAPWAP works by splitting the AP into two logical components, the CAPWAP protocol and the APP, and establishing a CAPWAP tunnel between the AP and the controller for communication.
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