# Configuring an L2TP LAC

An L2TP access concentrator (LAC) receives packets from a remote client and forwards them to an L2TP network server (LNS), on a remote network. You can configure your E Series router to function as an LAC.

This chapter includes the following topics that provide information for configuring an L2TP LAC on the E Series router:

- LAC Configuration Prerequisites
- Modifying L2TP LAC Default Settings for Managing Destinations, Tunnels, and Sessions
- Generating UDP Checksums in Packets to L2TP Peers
- Specifying a Destruct Timeout for L2TP Tunnels and Sessions
- Preventing Creation of New Destinations, Tunnels, and Sessions
- Shutting Down Destinations, Tunnels, and Sessions
- Specifying the Number of Retransmission Attempts
- Configuring Calling Number AVP Formats
- Mapping a User Domain Name to an L2TP Tunnel Overview
- Mapping User Domain Names to L2TP Tunnels from Domain Map Tunnel Mode
- Mapping User Domain Names to L2TP Tunnels from Tunnel Group Tunnel Mode
- Configuring the RX Speed on the LAC
- Managing the L2TP Destination Lockout Process
- Managing Address Changes Received from Remote Endpoints
- Configuring LAC Tunnel Selection Parameters