Definition du sigle "LNS"

   L2TP Access Concentrator (LAC)

      A node that acts as one side of an L2TP tunnel endpoint and is a

      peer to the L2TP Network Server (LNS).  The LAC sits between an

      LNS and a remote system and forwards packets to and from each.

      Packets sent from the LAC to the LNS requires tunneling with the

      L2TP protocol as defined in this document.  The connection from

      the LAC to the remote system is either local (see: Client LAC) or

      a PPP link.



   L2TP Network Server (LNS)

      A node that acts as one side of an L2TP tunnel endpoint and is a

      peer to the L2TP Access Concentrator (LAC).  The LNS is the

      logical termination point of a PPP session that is being tunneled

      from the remote system by the LAC.

5.0 Protocol Operation

   The necessary setup for tunneling a PPP session with L2TP consists of   two steps, (1) establishing the Control Connection for a Tunnel, and
   (2) establishing a Session as triggered by an incoming or outgoing
   call request. The Tunnel and corresponding Control Connection MUST be   established before an incoming or outgoing call is initiated. An L2TP
   Session MUST be established before L2TP can begin to tunnel PPP
   frames. Multiple Sessions may exist across a single Tunnel and
   multiple Tunnels may exist between the same LAC and LNS.