Matt,
The client that needs DHCPv6 services knows whether to use DHCPv6 based upon the information from a router on its link-local network. The router has two configurable bits in its Router Advertisement (RA)
available for this purpose:
* O bit — This allows the client to use DHCPv6 to retrieve other configuration parameters
This would be set to aquire dns-servers, but not the client's IP address.
* M bit — This allows the client to use DHCPv6 to retrieve an IPv6 address and
other parameters from a DHCPv6 server.
Cisco at this time has no support for rdnss options as far as I am aware (RFC5006). You are stuck utilizing DHCPv6, or use RADVD (
http://www.litech.org/radvd/) which does have support for DNS server options; however, at this point, you might as well use the DHCPv6 on Cisco and set the DNS server option.
Here is something that might help:
http://www.cisco.com/en/US/tech/tk872/technologies_white_paper09186a00801e199d.shtmlIf it is still failing, you might want to consider enabling some debug options and even setting up some captures to troubleshoot.
Billy
Good Luck