[ovs-dev] please help review patch "allow DHCPv6 respond multiple IA Address Options"

[Numan Siddique]

On Wed, Aug 31, 2016 at 8:44 AM, Zong Kai Li <zealokii at gmail.com> wrote:

> On Tue, Aug 30, 2016 at 8:28 PM, Numan Siddique <nusiddiq at redhat.com>
> wrote:
> >
> >
> > On Tue, Aug 30, 2016 at 9:40 AM, Ben Pfaff <blp at ovn.org> wrote:
> >>
> >> The patch will get reviewed, there's no need to ask again.
> >>
> >> On Tue, Aug 30, 2016 at 11:09:23AM +0800, Zong Kai Li wrote:
> >> > Hi, Numan and Justin.
> >> > I wish you can help review patch "allow DHCPv6 respond multiple IA
> >> > Address Options".
> >> > http://patchwork.ozlabs.org/patch/663493/
> >> >
> >> > For current DHCPv6 implementation, it will respond one IPv6 address
> >> > for a lswitch port in a DHCPv6 Reply message. The "one IPv6 address",
> >> > I mean, one in the same address string, like "MAC IPv4-Address
> >> > IPv6-Address-1 IPv6-Address-2 ...".
> >> >
> >> > I don't think it's a good solution, since we can set multiple IA
> >> > Address Options in a DHCPv6 Reply message, and by that, we can support
> >> > multiple IPv6 addresses in the same address string for VIF port to
> >> > configure. It will give us a lflow with action=(reg0[3] =
> >> > put_dhcpv6_opts(ia_addr = OFFER_IP1, ia_addr = OFFER_IP2, ... ,
> >> > server_id = MAC, OTHER_OPTS...); next;). This can work.
> >> >
> >> > In the patch mentioned above, I kept the CIDR checking, to make sure
> >> > at least one IPv6 address owned by lswitch port can reach DNS server
> >> > list in put_dhcpv6_opts action.
> >> >
> >
> >
> > I haven't reviewed the patch. But I have few comments.
> > A logical port can have multiple IPv6 addresses, out of which some can be
> > from a stateless subnet and some from stateful subnet. This doesn't
> handle
> > it right ? Correct me if I am wrong here.
> >
> > May be CMS can store the multiple IA_ADDR options in the
> > DHCP_Options.options so that ovn-northd doesn't need to bother about it.
> >
> > Thanks
> > Numan
> >
>
> Yes, you're right, this changing doesn't handle that stateful and
> stateless addresses case. I didn't have a confident solution, so I
> made this changing aims to let all addresses belong to VM/VIF port can
> be get at first.
>
> I think store the multiple IA_ADDR options in the DHCP_Options.options
> is a good solution for ovn-northd, but not to CMS, it will lead
> DHCP_Options.options has higher maintain workload.
>

​I would personally prefer this approach. As it is cleaner. I think it
should be fine for CMS to take care of such things. Else it could become
openstack specific. My 2 cents.

​


>
> Another idea is, allow Logical_Switch_Port.dhcpv6_options can have
> multiple refers than just one. Using this way to tell IPv6 addresses
> match DHCP_Options.cidr are stateful. It may be also possible to
> combine them into one, since dns server and domain in DHCP_Options
> referred by Logical_Switch_Port could be the same.
>
> That's all idea I get for now.
> Thanks and have a nice day. :)
> Zongkai LI
>