Exam 350-401 topic 1 question 935 discussion

CAPWAP is used between AP and WLC , Tunnels between 2 WCL = EoIP Ethernet Over IP

This document clears up this question and question 914. The tunnel is called a "mobility tunnel" but only CAPWAP can be used between 9800 and AireOS WLCs. Two AireOS WLCs must use EoIP instead of CAPWAP, but the tunnel is still a "mobility" tunnel (why Q914 can't be A:CAPWAP and must be C:mobility). https://www.cisco.com/c/en/us/td/docs/wireless/controller/technotes/8-8/b_c9800_wireless_controller-aireos_ircm_dg.pdf

A. CAPWAP (Control and Provisioning of Wireless Access Points) Explanation: CAPWAP is the protocol used for communication between access points and wireless controllers. It encapsulates both control and data traffic, enabling seamless roaming between access points, even across different Layer 3 networks. During Layer 3 roaming between a Cisco AireOS WLC and a Cisco IOS XE WLC, CAPWAP tunnels help maintain the client session without requiring reauthentication or disruption. Other options (IPsec, VPN, Ethernet over IP) are not designed for seamless roaming in the context of wireless controller-client communication.

Key : L3 tunnel for roaming → CAPWAP

A is correct

"A Layer 3 intercontroller roam involves building an additional CAPWAP tunnel between the client’s initial WLC and the WLC to which it has roamed. The tunnel transmits the data to and from the client just like it is still associated with the original IP subnet and WLC. When a Layer 3 roam happens, the original WLC is called the anchor controller, and the current WLC where the roamed client is reassociated is called the foreign controller. The client is anchored to the original WLC even if it roams to different controllers." https://study-ccnp.com/wlan-intercontroller-layer-2-layer-3-roaming/