What encryption method is used by default for user traffic in Remote AP tunnel mode?

In Remote AP (RAP) tunnel mode, user traffic is encrypted using link layer encryption protocols, specifically WPA2 or WPA3 (which are forms of link layer encryption). This method ensures that all data transmitted between the client and the access point is secured at the data link layer, providing effective protection against eavesdropping and unauthorized access.

Using link layer encryption is advantageous because it encapsulates the data as it travels over the wireless network, allowing for secure transmission without requiring additional layers of encryption like IPSec, which is not the default method in this context. While other methods of encryption exist, such as those using IPSec or data link layer encryption more generally, the correct answer highlights the specific utilization of the user's link layer encryption as the default for maintaining the confidentiality and integrity of the user traffic in Remote AP tunnel mode.