L2TP Access Concentrator
▀ Supported LAC Service Configurations for PDSN Simple IP
▄ Cisco ASR 5x00 Packet Data Network Gateway Administration Guide
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How The Attribute-based L2TP Configuration Works
The following figure and the text that follows describe how Attribute-based tunneling is performed using the system.
Figure 38.
Attribute-based L2TP Session Processing for SIP
1.
A subscriber session from the PCF is received by the PDSN service over the R-P interface.
2.
The PDSN service attempts to authenticate the subscriber. The subscriber could be configured either locally or
remotely on a RADIUS server. Figure above shows subscriber authentication using a RADIUS AAA server.
3.
The RADIUS server returns an Access-Accept message, which includes attributes indicating that session data is
to be tunneled using L2TP, and the name and location of the LAC service to use. An attribute could also be
provided indicating the LNS peer to connect to.
4.
The PDSN service receives the information and then forwards the packets to the LAC service, configured within
the Destination context.
5.
The LAC service, upon receiving the packets, encapsulates the information and forwards it to the appropriate
PDN interface for delivery to the LNS.
6.
The encapsulated packets are sent to the peer LNS through the packet data network where they will be un-
encapsulated.
Configuring Attribute-based L2TP Support for PDSN Simple IP
This section provides a list of the steps required to configure attribute-based L2TP support for use with PDSN Simple IP
applications. Each step listed refers to a different section containing the specific instructions for completing the required
procedure.
