Which tunnel type enables seamless Layer 3 client roaming between a Cisco AireOS WLC and a Cisco IOS XE WLC?

The Mobility tunnel type is specifically designed to facilitate seamless Layer 3 client roaming between Cisco Wireless LAN Controllers (WLCs), including a mix of AireOS and IOS XE platforms. It encapsulates client traffic and tunnels it between WLCs, allowing clients to retain their IP address and session state as they move across different subnets. IPsec and VPN are general-purpose secure tunneling protocols but don't inherently provide the Layer 3 roaming intelligence required for seamless client mobility in a wireless network. Ethernet over IP (EoIP) tunnels Layer 2 frames over an IP network, but it's not the primary or most efficient solution for Layer 3 client roaming between WLCs in a Cisco wireless architecture.