CDRouter Support

A dual-stack router providing IPv6 connectivity via native DHCPv6 on the WAN

knowledge-base version 12.13


Dual-stack CPE devices typically enable IPv6 connectivity via native IPv6 connections on the WAN or via tunneling protocols that transmit encapsulated IPv6 packets over the IPv4 WAN. Protocols such as DHCPv6 (with and without prefix delegation), PPPoE (running DHCPv6 or autoconf for address resolution), autoconf, or static IPv6 addressing can be used to provide native IPv6 connectivity on the WAN, whereas the most common tunneling protocols are 6to4 and 6rd. This recipe focuses on dual-stack CPE devices with native connections to the IPv6 WAN. A dual-stack recipe based on 6to4 tunneling over the IPv4 WAN can be found here.

Testing dual-stack devices with CDRouter is straightforward. The physical setup is the same as it would be for testing an IPv4 only device - CDRouter connects via Ethernet or wireless to the LAN side of the DUT, and via Ethernet, ATM, or T1/E1 to the WAN side of the DUT. However, when testing a dual-stack enabled device the logical test environment is quite different, as shown in the diagram below. The simulated WAN ISP is now dual-stack, as are a number of other simulated network elements, such as the DNS server(s) and ACS (if applicable). In this example the WAN ISP includes a DHCPv6 server which provides both address and prefix information to the DUT’s WAN DHCPv6 client.

The diagram and example configuration below assume DHCP for IPv4 connectivity on the WAN, and DHCPv6 with prefix delegation for IPv6 connectivity on the WAN. It is also assumed that the CPE is providing IPv6 addresses to all LAN clients via SLAAC (autoconf). The same basic methodology shown here applies to other native IPv6 connection modes such as PPPoE, autoconf, and static IPv6 addressing.

Test Setup

CDRouter Configuration

# -- IPv4 Configuration:

# WAN configuration
testvar wanInterface               eth2
testvar wanMode                    DHCP
testvar wanIspIp         
testvar wanIspAssignIp   
testvar wanNatIp         
testvar wanIspNextIp     
testvar wanIspMask       
testvar wanDnsServer     
testvar wanBackupDnsServer

# LAN configuration
testvar lanInterface               eth1
testvar lanMode                    DHCP
testvar lanIp            
testvar lanMask          

# DHCP Client
testvar dhcpClientStart  
testvar dhcpClientEnd    

# other configuration options
testvar remoteHostIp     

# -- IPv6 Configuration:

testvar supportsIPv6               yes

# IPv6 WAN configuration
testvar ipv6WanMode                DHCP
testvar ipv6WanIspIp               3001::1 
testvar ipv6WanIspAssignIp         3001::2
testvar ipv6WanIspNextIp           3001::3
testvar ipv6WanIspPrefixLen        64

testvar ipv6WanDnsServer           3001:51a:cafe::2
testvar ipv6WanBackupDnsServer     3001:51a:cafe::3

# DHCPv6 Prefix Delegation
testvar dhcpv6WanEnablePD          yes 
testvar dhcpv6WanAssignPrefix      3001:dddd::
testvar dhcpv6WanAssignNextPrefix  3001:ddde::
testvar dhcpv6WanAssignPrefixLen   48 
testvar dhcpv6PDLatency            30

# LAN configuration
testvar ipv6LanMode                autoconf
testvar ipv6LanIp                  ::1
testvar ipv6RAInterval             300
testvar ipv6LanSubnetId            1

# other configuration options
testvar ipv6RemoteHost             3001:51a:cafe::1
testvar ipv6FreeNetworkStart       3001:cafe:1::
testvar ipv6FreeNetworkPrefixLen   64
testvar ipv6FreeNetworkStop         3001:cafe:ffff::


  • CDRouter or CDRouter Multiport
  • The CDRouter IPv6 add-on module
  • Two dedicated Ethernet network interfaces
  • One dual-stack router with DHCPv6 and prefix delegation support on the WAN


  • Simple setup, great for a stand-alone test station
  • Allows devices supporting DHCPv6 with prefix delegation to be tested
  • Perfect for debugging test failures and testing functionality in a dual-stack environment
  • Quickly verifies routing is properly configured for IPv6

Additional Information

Please see the CDRouter IPv6 User’s Guide for more information.



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