Feature history for ip reassembly, Layer 2 access concentrator – Cisco 10000 User Manual

Page 166

Advertising

5-2

Cisco 10000 Series Router Software Configuration Guide

OL-2226-23

Chapter 5 Configuring the Layer 2 Tunnel Protocol Access Concentrator and Network Server

Layer 2 Access Concentrator

Feature History for IP Reassembly

Layer 2 Access Concentrator

The Cisco 10000 series router supports the Layer 2 access concentrator (LAC) feature. When configured
as the LAC, the Cisco 10000 series router functions as the service provider’s network access server.
Remote subscribers use a local or point-to-point connection to initiate a PPPoA or PPPoE session to the
LAC. The LAC terminates the physical connection and forwards the PPP session to the provider’s Layer
2 Tunnel Protocol network server (LNS).

The LAC connects to the LNS using a local area network or a wide area network such as public or private
ATM. The LAC directs subscriber sessions into Layer 2 Tunnel Protocol (L2TP) tunnels based on the
domain of each session. The LAC acts as one side of an L2TP tunnel endpoint and is a peer to the LNS
on the other side of the tunnel. The LAC forwards packets to and from the LNS and a remote system.

Acting as the LNS, you can configure the Cisco 10000 series router to terminate the PPP sessions and
route the client IP packets onto the ISP or corporate network toward their final destination (

Figure 5-1

You can also configure the LNS to place the sessions in VRFs before routing the packets, as shown in

Figure 5-2

The LAC feature is described in the following topics:

•

Tunnel Sharing, page 5-4

•

Tunnel Service Authorization, page 5-4

•

Sessions per Tunnel Limiting, page 5-5

•

Session Load Balancing, page 5-6