In the voluntary tunnel model, a tunnel is created by the user, typically by the use of an L2TP-enabled client.
As a result, the user sends L2TP packets to the ISP, which forwards them on to the LNS. In voluntary tunneling the ISP does not need to support L2TP, and the L2TP tunnel initiator effectively is on the same system as the remote client. In this model, the tunnel extends across the entire PPP session from the L2TP client to the LNS.