Cisco ASR 5x00 Packet Data Network Gateway Administration Guide ▄
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Appendix G
L2TP Access Concentrator
This chapter describes the Layer 2 Tunneling Protocol (L2TP) Access Concentrator (LAC) functionality support on
Cisco® ASR 5x00 chassis and explains how it is configured.
The product Administration Guides provide examples and procedures for configuration of basic services on the system.
It is recommended that you select the configuration example that best meets your service model, and configure the
required elements for that model, as described in the respective product Administration Guide, before using the
procedures in this chapter.
Important:
The L2TP Access Concentrator is a licensed Cisco feature. A separate feature license may be
required. Contact your Cisco account representative for detailed information on specific licensing requirements. For
information on installing and verifying licenses, refer to the
Managing License Keys
section of the
Software
Management Operations
chapter in the
System Administration Guide
.
When enabled though the session license and feature use key, the system supports L2TP for encapsulation of data
packets between it and one or more L2TP Network Server (LNS) nodes. In the system, this optional packet
encapsulation, or tunneling, is performed by configuring L2TP Access Concentrator (LAC) services within contexts.
Important:
The LAC service uses UDP ports 13660 through 13668 as the source port for sending packets to the
LNS.