ipv6 prefix delegation and dns problems

Unanswered Question
Jun 2nd, 2012
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Hello everyone.

Recently I've encountered a problem in the following ipv6 dhcp deployment:

(ipv6 dhcp server) ----------- (client router) ----------- (windows host)

The task was to use existing ipv6 dhcp server which was built on linux machine and configured for prefix delegation. In this case router is in the role of requesting router with the follwing configuration:

interface FastEthernet0/1      (interface to dhcp server in client mode)

no ip address

duplex auto

speed auto

ipv6 address 2010:AB8:0:1::2/64

ipv6 enable

ipv6 dhcp client pd from_isp

interface FastEthernet0/0     (interface to client machines)

ip address

duplex auto

speed auto

ipv6 address from_isp ::1:0:0:0:1/64

ipv6 enable

Client router has received prefix: show ipv6 dhcp int

FastEthernet0/1 is in client mode

  State is OPEN

  Renew will be sent in 00:01:58

  List of known servers:

    Reachable via address: 2010:AB8:0:1::1

    DUID: 00010001001BD5EF900202000000

    Preference: 0

    Configuration parameters:

      IA PD: IA ID 0x00040001, T1 120, T2 120

        Prefix: 2001:DB8:1200::/48

                preferred lifetime 300, valid lifetime 600

                expires at Jun 02 2012 09:09 PM (599 seconds)

      DNS server: 2010:AB8:0:1::1

      Domain name: example.com

  Prefix name: from_isp

  Rapid-Commit: disabled

Output from show ipv6 general-prefix  :

IPv6 Prefix from_isp, acquired via DHCP PD

  2001:DB8:1200::/48 Valid lifetime 550, preferred lifetime 250

   FastEthernet0/0 (Address command)

Result: windows machine has received prefix, used autoconfiguration to built host part of address, installed default route, but! there is no any dns information installed.

What can be done to resolve this problem? Can we influence on what type (stateful/stateless) dhcp client router uses for windows machine in case of prefix delegation? Can the delegated prefix be used in dhcp server pool on client router?

thanks in advance.

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lgijssel Sun, 06/03/2012 - 23:00
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Try what happens when the router interface is not in client mode.

Instead configure the required prefix on it.



alex_noc777 Mon, 06/04/2012 - 01:09
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Before client mode and prefix delegation I've tested solution when router was a relay, this scheme worked perfectly. But the task is to configure prefix delegation...everything works except DNS.

jrabinek96349 Thu, 06/21/2012 - 07:07
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Give the following a try, if you haven't already gotten to the bottom of this.  This should still perform stateless configuration for your clients, but the "other" flag will prompt the clients to get the dns servers from the listed dhcp pool


ipv6 dhcp pool dhcp-pool

dns-server 2001:XXX:XXX::X

dns-server 2001:XXX:XXX::X

domain-name xxxxx.xxx


interface FastEthernet0/0     (interface to client machines)

ip address

duplex auto

speed auto

ipv6 address from_isp ::1:0:0:0:1/64

ipv6 enable

ipv6 nd other-config-flag

ipv6 dhcp server dhcp-pool



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