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Knowledge Base > The CDRouter Cookbook > A DHCP relay setup

A DHCP relay setup

In some cases it may be necessary to include an additional router in the test setup. CDRouter supports this type of scenario when the DUT's WAN connection mode is static or DHCP only.

In the example test setup shown below, an additional router is used to route between an ATM network and an Ethernet network. In this case the DUT is a DSL CPE that is connecting to an ATM-based DSLAM. The router eliminates the need for installing a separate ATM interface in the CDRouter host system. Note that the ATM/Ethernet router must be configured as a DHCP relay agent in this setup.

Test Setup

CDRouter Configuration

To configure CDRouter for DHCP relay, three additional testvars, wanIspGateway, wanIspAssignGateway, and IPv4hopCount must be included in the CDRouter configuration file. A sample CDRouter configuration based on the test setup above is provided here: 

  # -- Sample CDRouter DHCP relay configuration

  testvar wanMode DHCP

  testvar wanIspIp 10.0.0.1
  testvar wanIspGateway 10.0.0.2
  testvar wanIspMask 255.255.255.0

  testvar wanIspAssignIp 4.0.0.2
  testvar wanIspAssignGateway 4.0.0.1
  testvar wanNatIp 4.0.0.2

  testvar wanIspNextIp 4.0.0.10

  testvar IPv4 hopCount 2

Requirements

  • CDRouter or CDRouter-Multiport
  • Two dedicated Ethernet network interfaces
  • One DSL router
  • One ATM-based DSLAM
  • One router with an ATM and Ethernet interface

Benefits

  • Allows more complex network topologies to be tested with CDRouter
  • Can be used to eliminate some hardware requirements, such as an ATM interface when an ATM-based DSLAM is used

Additional Information

Please see Chapter 5 of the CDRouter User's Guide for more information.