L2TP tunnel and session

An L2TP tunnel is a virtual point-to-point connection between an LAC and an LNS. Multiple L2TP tunnels can be established between an LNS and an LAC. An L2TP tunnel can carry one or more L2TP sessions. Each L2TP session corresponds to a PPP session and is multiplexed on an L2TP tunnel. An L2TP session is established between the LAC and LNS when an end-to-end PPP session is established between a remote system and the LNS. Data frames for the PPP session are transmitted over the tunnel between the LAC and LNS.