The Tunnel Authentication via RADIUS on Tunnel Terminator feature allows the Layer 2 Tunneling
Protocol (L2TP) network server (LNS) to perform remote authentication and authorization with
RADIUS on incoming L2TP access concentrator (LAC) dialin connection requests. This feature also
allows the L2TP LAC to perform remote authentication and authorization with RADIUS on incoming
L2TP LNS dialout connection requests.

Before the introduction of this feature, the LNS could only perform L2TP tunnel authentication and
authorization locally. These processes can be difficult to maintain across numerous LNSs, especially if
the number of virtual private dialup network (VPDN) groups is large, because the LAC information must
be configured under the VPDN group configurations of the LNS. Remote RADIUS authentication and
authorization allows users to store the LAC configurations on the RADIUS server, thereby avoiding the
need to store information locally. Thus, the new LAC information can be added to the RADIUS server
as necessary, and the group of LNSs can authenticate and authorize by using a common user database on
RADIUS.

Release

Modification

12.2(15)B

This feature was introduced on the Cisco 6400 series, Cisco 7200 series,
and Cisco 7400 series.

12.3(4)T

This feature was integrated into Cisco IOS Release 12.3(4)T.