CDRouter Support

A dual-stack router providing IPv4 connectivity via DS-Lite over the IPv6 WAN

knowledge-base version 10.3


In this model we see that NAT has been moved from the CPE to the ISP. The CPE is now a Basic Bridging BroadBand element (B4), in DS-Lite terminology. The ISP end, perhaps amusingly, is named the AFTR (Address Family Transition Router). Packets with private addresses leave the B4 CPE untranslated. After decapsulation by the AFTR, they have NAT applied and are routed onto the IPv4 Internet. Users with IPv4 only devices will effectively see no changes from the current model of CPE based NAT. Media devices, LAN enabled smart phones, gaming consoles, laptops and workstations alike will continue operating with zero configuration changes. This model is desirable because it mitigates support costs to everyone: ISPs will have fewer consumer support issues, and businesses will have smaller network administration costs.

Test Setup

CDRouter Configuration

# -- IPv4 Configuration:

# WAN configuration
testvar wanInterface              eth2
testvar wanMode                   dslite
testvar wanIspIp        
testvar wanIspAssignIp  
testvar RemoteHost      

# LAN configuration
testvar lanInterface              eth1
testvar lanIp           
testvar lanMask         
testvar dhcpClientStart 
testvar dhcpClientEnd   

# -- IPv6 Configuration:

testvar supportsIPv6              yes

# WAN configuration
testvar ipv6WanMode               DHCP
testvar ipv6WanIspIp              3001::1
testvar ipv6WanIspAssignIp        3001::2
testvar ipv6WanIspNextIp          3001::3
testvar ipv6WanIspPrefixLen       64
testvar dhcpv6WanEnablePD         yes
testvar dhcpv6WanAssignPrefix     3001:dddd::
testvar dhcpv6WanAssignNextPrefix 3001:ddde::
testvar dhcpv6WanAssignPrefixLen  48
testvar dhcpv6PDLatency           30

# DS-Lite AFTR configuration
testvar ipv6DsliteAftr            3001:aaaa::1
testvar dhcpv6WanAftrName

# LAN configuration
testvar ipv6LanMode               autoconf
testvar ipv6LanIp                 ::1
testvar ipv6LanSubnetId           1
testvar ipv6WanDnsServer          3001:51a:cafe::2
testvar ipv6WanBackupDnsServer    3001:51a:cafe::3

# other configuration options
testvar ipv6RemoteHost            3001:51a:cafe::1
testvar ipv6FreeNetworkStart      3001:cafe:1::
testvar ipv6FreeNetworkEnd        3001:cafe:ffff::
testvar ipv6FreeNetworkPrefixLen  64


  • CDRouter or CDRouter Multiport
  • The CDRouter IPv6 add-on module
  • Two dedicated Ethernet network interfaces
  • One dual-stack router with DS-Lite support


  • Simple setup, great for a stand-alone test station
  • Allows DS-Lite enabled devices to be tested in isolation
  • Perfect for debugging test failures and testing functionality in a dual-stack environment
  • Useful for ensuring IPv4 connectivity when IPv6 WAN connection renumbers
  • Useful for verifying IPv4 and NAT related functionality in a DS-Lite environment

Additional Information

Please see the CDRouter IPv6 User’s Guide and our Application Note on DS-Lite for more information.



About CDRouter

CDRouter is made by QA Cafe, a technology company based in Portsmouth, NH.

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