My guess is that your dhcp client running inside the VM set up the subnet mask as /128. Dhcpv6 doesn¹t provide prefix length, but the client system sometime adds the net mask based on the link type. Some of the dhcp clients use a script to configure the interface, and I think you can use /64 if your link is ethernet. ‹Robert On 2/19/15, 4:27 AM, "Andreas Scheuring" <scheuran at linux.vnet.ibm.com> wrote: >Hi, >I was playing around with the various dhcp/radvd options of neutron. >Very helpful was the matrix [1] that describes the combinations of ra >and adress mode that can be configured. > >For dhcpv6-stateful (ra & adress mode) it says: "VM obtains IPv6 address >from dnsmasq using DHCPv6 stateful and optional info from dnsmasq using >DHCPv6 stateful" [1] --> My assumption was that IP adresses and prefix >are assigned via dnsmasq. > >But going this way, my instances got the right IP-Adress (great) but >always the subnetmask /128, although I configured /64. Dumping the >traffic and having a look at dnsmasq logs the dhcp process from solicit >to reply worked fine. > >I was using rhel7 for guest and host and dnsmasq 2.68. > >I googled around and found some hints, that dhcpv6 does not support >prefix delegation. Seems like that it is the job of the radvd daemon >[2][3][4] > > >Is that true? And if so, what's the use case of configuring >dhcpv6-stateful for ra and address mode? > > > > > > >[1] >http://specs.openstack.org/openstack/neutron-specs/specs/juno/ipv6-radvd-r >a.html#rest-api-impact > >[2] https://lists.isc.org/pipermail/dhcp-users/2012-May/015446.html >[3] >http://serverfault.com/questions/528387/sending-netmask-and-gateway-route- >with-dhcp-for-ipv6 >[4] >https://supportforums.cisco.com/document/116221/part-1-implementing-dhcpv6 >-stateful-dhcpv6 > >-- >Andreas >(irc: scheuran) > > > > >__________________________________________________________________________ >OpenStack Development Mailing List (not for usage questions) >Unsubscribe: OpenStack-dev-request at lists.openstack.org?subject:unsubscribe >http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev