What type of messages does the control part of L2TP handle?

The control part of L2TP (Layer 2 Tunneling Protocol) is specifically focused on handling control messages that are crucial for establishing and maintaining tunnels between two endpoints. This process includes managing the setup of the tunnel, negotiating parameters, and maintaining the state of the session throughout its lifecycle. Control messages facilitate the communication necessary for establishing a connection, such as initiating a session, terminating it, and coordinating link maintenance.

In a typical L2TP session, the control messages are essential for signaling and ensuring that both sides of the connection agree on how to interact and what tunnels to maintain. This aspect is distinct from other types of messages that may be transmitted, such as data messages, which are the actual user data traveling through the tunnel, or authentication messages, which verify the identity of users before allowing access to resources. Connection supervision is a broader term that might refer to the ongoing management of a connection but is not specific enough to the role of control messages in the context of L2TP. Thus, it is the control messages that are fundamental to the operation of L2TP, making this the correct answer.