L2Tp Lac Support - Cisco ASR 5000 series Product Overview

▀ Features and Functionality - Optional Enhanced Software Features
Control and configuration of the above is specified as part of the subscriber configuration on the PDSN, e.g., IPv6
address prefix and parameters for the IPv6 router advertisements. RADIUS VSAs may be used to override the
subscriber configuration.
Following IPv6 PDP context establishment, the PDSN can perform either manual or automatic 6to4 tunneling,
according to RFC 3056, Connection of IPv6 Domains Via IPv4 Clouds.

L2TP LAC Support

The system configured as a Layer 2 Tunneling Protocol Access Concentrator (LAC) enables communication with L2TP
Network Servers (LNSs) for the establishment of secure Virtual Private Network (VPN) tunnels between the operator
and a subscriber's corporate or home network.
Description
The use of L2TP in VPN networks is often used as it allows the corporation to have more control over authentication
and IP address assignment. An operator may do a first level of authentication, however use PPP to exchange user name
and password, and use IPCP to request an address. To support PPP negotiation between the PDSN and the corporation,
an L2TP tunnel must be setup in the PDSN running a LAC service.
L2TP establishes L2TP control tunnels between LAC and LNS before tunneling the subscriber PPP connections as
L2TP sessions. The LAC service is based on the same architecture as the PDSN and benefits from dynamic resource
allocation and distributed message and data processing. This design allows the LAC service to support over 4000 setups
per second or a maximum of over 3G of throughput. There can be a maximum up to 65535 sessions in a single tunnel
and as many as 500,000 L2TP sessions using 32,000 tunnels per system.
The LAC sessions can also be configured to be redundant, thereby mitigating any impact of hardware of software
issues. Tunnel state is preserved by copying the information across processor cards.
Important:
chapter in System Enhanced Feature Configuration Guide.
L2TP LNS Support
The system configured as a Layer 2 Tunneling Protocol Network Server (LNS) supports the termination secure Virtual
Private Network (VPN) tunnels between from L2TP Access Concentrators (LACs).
Description
The LNS service takes advantage of the high performance PPP processing already supported in the system design and is
a natural evolution from the LAC. The LNS can be used as a standalone, or running alongside a PDSN service in the
same platform, terminating L2TP services in a cost effective and seamless manner.
▄ Cisco ASR 5000 Series Product Overview
For more information on L2TP Access Concentrator support, refer L2TP Access Concentrator
CDMA2000 Wireless Data Services
OL-22938-02