Microsoft Certified Systems Engineer (MCSE) Question:

Voluntary Tunneling:
Users computer is an end point of the tunnel and acts as tunnel client. Here the client or user issues a request to configure and create a voluntary tunnel. They require a dial up or LAN connection. Example of dial up connection is internet at home where a call is made to the ISP and connection is obtained.

Compulsory tunneling:
In compulsory tunneling, instead of the user a vpn remote access server configures and creates a tunnel. Hence, the end point is the Remote sever not the user.