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Cisco 10000 Series Router Software Configuration Guide
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Chapter 5      Configuring the Layer 2 Tunnel Protocol Access Concentrator and Network Server
L2TP Network Server
Required Configuration Tasks for LNS
To configure the Cisco 10000 series router as an LNS, perform the following required configuration 
tasks:
  • Configuring the Virtual Template Interface, page 5-29
  • Configuring the LNS to Initiate and Receive L2TP Traffic, page 5-29
Note You must also configure the LAC and RADIUS server to communicate with the LNS. For more 
information, see the 
“Required Configuration Tasks for LAC” section on page 5-7 or see your RADIUS 
documentation. 
Configuring the Virtual Template Interface 
To configure a virtual template interface, enter the following commands:
Configuring the LNS to Initiate and Receive L2TP Traffic
To configure the Cisco 10000 router, acting as the LNS, to initiate and receive L2TP traffic, enter the 
following commands:
Command Purpose
Step 1
Router> enable
Enters privileged EXEC mode.
Step 2
Router# config terminal
Enters global configuration mode.
Step 3
Router(config)# interface virtual-template 
number
Creates a virtual template interface and enters interface 
configuration mode.
Step 4
Router(config-if)# ip vrf forwarding <name>
Maps the virtual template interface to a VRF routing table.
Step 5
Router(config-if)# ip unnumbered loopback 
<number>
Enables IP without assigning a specific IP address on the 
LAN.
Step 6
Router(config-if)# ppp authentication {pap | 
chap | ms-chap}
Enables PAP or CHAP authentication on the virtual 
template interface, which is applied to VAIs.
Command Purpose
Step 1
Router> enable
Enters privileged EXEC mode.
Step 2
Router# config terminal
Enters global configuration mode.
Step 3
Router(config)# vpdn enable
Enables VPDN networking on the router and informs the 
router to look for tunnel definitions in a local database 
and on a remote authorization server (home gateway) if 
one is present.
Step 4
Router(config)# vpdn-group group-name
Defines a local group name for which you can assign other 
VPDN variables. Enters VPDN group configuration mode.
Step 5
Router(config-vpdn)# accept-dialin 
Configures the LNS to accept tunneled PPP connections 
from the LAC and creates an accept-dialin VPDN 
subgroup.