DHCPv6 Router Option

David Farmer farmer at umn.edu
Fri Aug 6 00:49:50 UTC 2010

On 8/5/10 09:55 CDT, Bradlee Landis wrote:
> I've had a rather hard time narrowing down what my problem is (listed
> at http://serverfault.com/questions/167410/windows-7-failing-ping-on-ipv6-in-dhcp-setup),
> and I think I've finally figured out that Windows 7 does not put the
> proper routes in place unless a default router is listed. I cannot for
> the life of me find the option to set the router in dhcpd6.conf.
> `option routers` only works for IPv4. and I tried adding the `option
> dhcp6.defgateway code 99 = ip6-address` variable, and setting it, but
> that did nothing.
> Any ideas?

In IPv6 routers are learned via ICMP Router Advertisements (RAs), so 
your IPv6 router needs to advertise itself with an RA.  If you want to 
have the DHCPv6 server manage the address assignments (Stateful DHCPv6), 
then you should set the "M" flag in the RA from the router.  If you want 
a client to do SLAAC and only use the DHCPv6 server for other 
information (Stateless DHCPv6), then you should to set the "O" flag in 
the RA from the router.

David Farmer               Email:farmer at umn.edu
Networking & Telecommunication Services
Office of Information Technology
University of Minnesota	
2218 University Ave SE	    Phone: 612-626-0815
Minneapolis, MN 55414-3029   Cell: 612-812-9952

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