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DHCPv6 Prefix Delegation in Windows Vista

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In a previous post, I had discussed the DHCPv6 client behaviour in Windows Vista. A few customers who're evaluating IPv6 in Windows Vista responded asking about the support for DHCPv6 Prefix Delegation and/or asked why the Vista DHCPv6 client doesn't request an IPv6 subnet prefix by default. In most cases, this question came from Japan where users tried to test IPv6 broadband network connections with Windows Vista and their ISP was allocating a /64 IPv6 prefix to each customer. I'll address this query here.

 

A host running Windows Vista is by default a network end-point. Network traffic is initiated and terminated on this machine, but this machine does not actively participating in the routing of network traffic for other hosts. DHCPv6 Prefix Delegation is intended for network elements that behave as a router. The terminology used in RFC 3633 ["IPv6 Prefix Options for DHCPv6"] indicates this: the client requesting an IPv6 prefix is called the "requesting router", and the server which leases the IPv6 prefix is termed the "delegating router". Since the host running Windows Vista doesn't behave as a router by default, the DHCPv6 client doesn't request an IPv6 prefix by default from the server.

 

Windows Vista can be used to route network traffic when specific features are used. DHCPv6 Prefix Delegation support in Vista is hence initiated only when these features are enabled. An example of such features is Internet Connection Sharing (ICS). When ICS is enabled on a network interface, Windows Vista can route traffic between other hosts on the same link and the network to which that interface is attached. So when ICS is enabled in Windows Vista, it will act as a requesting router and send a DHCPv6 Solicit message on that network interface in order to obtain an IPv6 subnet prefix for its link. The IPv6 subnet prefix obtained through this means is then included in the Router Advertisements sent out to the other machines on that link, in order to allow them to configure an IPv6 address based on the prefix obtained.

 

To support 3rd party applications from other ISVs that want to enable similar routing scenarios on Windows Vista and in Windows Server 2008, we provide DHCPv6 APIs for Prefix Delegation. See the DHCP client API documentation for Windows Vista under https://msdn2.microsoft.com/en-us/library/aa363344.aspx for further details - specifically, the APIs Dhcpv6RequestPrefix, Dhcpv6RenewPrefix and Dhcpv6ReleasePrefix.

 

I hope you find this information useful for understanding the DHCPv6 behaviour and for developing with IPv6 for Windows Vista and Windows Server 2008!!

 

Santosh Chandwani

Windows Enterprise Networking

 

[This posting is provided "AS IS" with no warranties, and confers no rights.]

Comments

  • Anonymous
    January 01, 2003
    The ipv6 address and options from Dhcp Server, when interface state is set to satteful mode.Please run the following netsh command for interface connected to Dhcp Server, to set it to stateful mode : netsh interface set interface <interface_name> adv=en man=en

  • Anonymous
    January 01, 2003
    La implementación de DHCPv6 en Windows Server 2008 es un área en la cual las bondades de red han sido

  • Anonymous
    January 01, 2003
    The comment has been removed

  • Anonymous
    July 16, 2007
    how can i assign ip address in ipv6 win vista

  • Anonymous
    December 30, 2009
    Hi ipv6 team, Does windows 2008 R2  support DHCPv6 Prefix Delegation  and RFC5006 ?

  • Anonymous
    January 07, 2010
    Hi Norman, No, Windows 2008 R2 Dhcp Server does not support Prefix Delegation and RFC 5006. There is support in Dhcp Client for Prefix-delegation (RFC 3633), to request ipv6 preifx from a Dhcp Server. Please refer to prefix related Api's, in below link for more information : http://msdn.microsoft.com/en-us/library/aa363346(VS.85).aspx  Ravi

  • Anonymous
    April 10, 2010
    Hi Ipv6 team How i can implement dhcpv6 client at vista? it's look fail get IPv6 address from server.

  • Anonymous
    February 11, 2011
    I have seen that a WindowXP CPE wants to see an RA with a /64 prefix; however, I don't see XP respond with SLACC to a /60 or /48.  Why would I see this behavior?

  • Anonymous
    February 11, 2011
    Can XP handle a router advertisement and do SLAAC with a prefix other than /64?