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We do have the Ironic inspector enabled but mainly use out-of-band such as
iDRAC.

I am indeed not using segments. I'll need to research that a bit more.

One important note, we are only using provider networks with no Neutron
routers. All routing is done on the physical network which aligns with the
docs for segments. The provisioning subnet is on 10.10.0.0/16 for the
directly attached nodes. As a test, I created a second subnet, 10.100.0.0/16,
on the same Neutron network with DHCP enabled, so now I have two subnets on
the same network and Neutron DHCP port. However, if DHCP relay requires
different segments per remote network...

The Networking service defines a segment using the following components:

   - Unique physical network name
   - Segmentation type
   - Segmentation ID


Does having unique physical network names also mean unique physical
interfaces?
Does this mean no flat network for segments?
If I create 10.100.0.0/16 in rack A1 and the controller is in D30, am I
pointing the DHCP relay to the DHCP agent's 10.10.0.0/16 IP address?


+--------------------+-------+---------------------------+
| Agent Type         | Alive | Binary                    |
+--------------------+-------+---------------------------+
| Baremetal Node     | :-)   | ironic-neutron-agent      |
| Baremetal Node     | :-)   | ironic-neutron-agent      |
| Baremetal Node     | :-)   | ironic-neutron-agent      |
| Baremetal Node     | :-)   | ironic-neutron-agent      |
| Linux bridge agent | :-)   | neutron-linuxbridge-agent |
| Baremetal Node     | :-)   | ironic-neutron-agent      |
| Metering agent     | :-)   | neutron-metering-agent    |
| Baremetal Node     | :-)   | ironic-neutron-agent      |
| Baremetal Node     | :-)   | ironic-neutron-agent      |
| Baremetal Node     | :-)   | ironic-neutron-agent      |
| DHCP agent         | :-)   | neutron-dhcp-agent        |
| L3 agent           | :-)   | neutron-l3-agent          |
| Baremetal Node     | :-)   | ironic-neutron-agent      |
| Baremetal Node     | :-)   | ironic-neutron-agent      |
| Metadata agent     | :-)   | neutron-metadata-agent    |
| Baremetal Node     | :-)   | ironic-neutron-agent      |
| Baremetal Node     | :-)   | ironic-neutron-agent      |
| Baremetal Node     | :-)   | ironic-neutron-agent      |
+--------------------+-------+---------------------------+

On Mon, Jun 1, 2020 at 4:34 PM <dsneddon at redhat.com> wrote:

> You will have to target two IP addresses with DHCP relay if you are
> using Ironic Inspector. The first is the IP where Ironic Inspector is
> listening with dnsmasq, usually the IP of the host itself. I know this
> doesn't lend itself to HA scenarios, but you might also be able to
> forward to the broadcast IP of the subnet where the Ironic Inspector
> will be running (I haven't tested this, but it is a common use case for
> DHCP relay).
>
> The second IP address is that of the Neutron DHCP agent, and that will
> be used for deploying bare metal nodes. IIRC, this IP is shared with
> the Neutron router for the network if you are using the L3 agent as
> well.
>
> If you are not running Ironic Inspector (and manually entering in
> baremetal host details instead), then you can forward DHCP relay only
> to the Neutron DHCP agent.
>
> Both of these IP addresses will be on the "root" subnet which is
> associated with the segment with the controller node(s).
>
> It sounds like you created a second subnet, but I'm not sure if you
> created the second subnet on a different segment from the first subnet.
> In Neutron routed networking, the segments determine whether a subnet
> is local or remote to the controller node(s). Typically the first
> segment would be the one local to the controller(s). Are you sure you
> enabled the segments plugin and created your second subnet on a new
> segment?
>
> Another approach which does not involve DHCP relay is to deploy DHCP
> agents locally on compute nodes local to each segment. This way all
> DHCP will be done within the same L2 domain, and you will not have to
> configure DHCP relay on your router serving each segment/subnet.
>
> See the docs for more info:
>
> https://docs.openstack.org/newton/networking-guide/config-routed-networks.html
>
> -Dan
>
> On Fri, 2020-05-29 at 10:47 -0600, Thomas King wrote:
> > In the Triple-O docs for unicast DHCP relay, it doesn't exactly say
> > which IP address to target. Without deploying Triple-O, I'm not clear
> > if the relay IP should be the bridge interface or the DHCP device.
> >
> > The first method makes sense because the gateway for that subnet
> > wouldn't be connected to the Ironic controller by layer 2 (unless we
> > used VXLAN over the physical network).
> >
> > As an experiment, I created a second subnet on my provisioning
> > network. The original DHCP device port now has two IP addresses, one
> > on each subnet. That makes the second method possible if I targeted
> > its original IP address.
> >
> > Thanks for the help and please let me know which method is correct.
> >
> > Tom King
> >
> > On Fri, May 29, 2020 at 3:15 AM Dan Sneddon <dsneddon at redhat.com>
> > wrote:
> > > You probably want to enable Neutron segments and use the Neutron
> > > routed networks feature so you can use different subnets on
> > > different segments (layer 2 domains AKA VLANs) of the same network.
> > > You specify different values such as IP allocation pools and router
> > > address(es) for each subnet, and Ironic and Neutron will do the
> > > right thing. You need to enable segments in the Neutron
> > > configuration and restart the Neutron server.  I don’t think you
> > > will have to recreate the network. Behind the scenes, dnsmasq will
> > > be configured with multiple subnets and address scopes within the
> > > Neutron DHCP agent and the Ironic Inspector agent.
> > >
> > > Each segment/subnet will be given a different VLAN ID. As Dmitry
> > > mentioned, TripleO uses that method for the provisioning network,
> > > so you can use that as an example. The provisioning network in
> > > TripleO is the one referred to as the “control plane” network.
> > >
> > > -Dan
> > >
> > > On Fri, May 29, 2020 at 12:51 AM Dmitry Tantsur <
> > > dtantsur at redhat.com> wrote:
> > > > Hi Tom,
> > > >
> > > > I know for sure that people are using DHCP relay with ironic, I
> > > > think the TripleO documentation may give you some hints (adjusted
> > > > to your presumably non-TripleO environment):
> > > >
> http://tripleo.org/install/advanced_deployment/routed_spine_leaf_network.html#dhcp-relay-configuration
> > > >
> > > > Dmitry
> > > >
> > > > On Thu, May 28, 2020 at 11:06 PM Amy Marrich <amy at demarco.com>
> > > > wrote:
> > > > > Hey Tom,
> > > > >
> > > > > Forwarding to the OpenStack discuss list where you might get
> > > > > more assistance.
> > > > >
> > > > > Thanks,
> > > > >
> > > > > Amy (spotz)
> > > > >
> > > > > On Thu, May 28, 2020 at 3:32 PM Thomas King <
> > > > > thomas.king at gmail.com> wrote:
> > > > > > Good day,
> > > > > >
> > > > > > We have Ironic running and connected via VLANs to nearby
> > > > > > machines. We want to extend this to other parts of our
> > > > > > product development lab without extending VLANs.
> > > > > >
> > > > > > Using DHCP relay, we would point to a single IP address to
> > > > > > serve DHCP requests but I'm not entirely sure of the Neutron
> > > > > > network/subnet configuration, nor which IP address should be
> > > > > > used for the relay agent on the switch.
> > > > > >
> > > > > > Is DHCP relay supported by Neutron?
> > > > > >
> > > > > > My guess is to add a subnet in the provisioning network and
> > > > > > point the relay agent to the linuxbridge interface's IP:
> > > > > > 14: brq467f6775-be: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu
> > > > > > 1500 qdisc noqueue state UP group default qlen 1000
> > > > > >     link/ether e2:e9:09:7f:89:0b brd ff:ff:ff:ff:ff:ff
> > > > > >     inet 10.10.0.1/16 scope global brq467f6775-be
> > > > > >        valid_lft forever preferred_lft forever
> > > > > >     inet6 fe80::5400:52ff:fe85:d33d/64 scope link
> > > > > >        valid_lft forever preferred_lft forever
> > > > > >
> > > > > > Thank you,
> > > > > > Tom King
> > > > > > _______________________________________________
> > > > > > openstack-mentoring mailing list
> > > > > > openstack-mentoring at lists.openstack.org
> > > > > >
> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-mentoring
> > >
> > > --
> > > Dan Sneddon         |  Senior Principal Software Engineer
> > > dsneddon at redhat.com |  redhat.com/cloud
> > > dsneddon:irc        |  @dxs:twitter
> --
> Dan Sneddon         |  Senior Principal Software Engineer
> dsneddon at redhat.com |  redhat.com/cloud
> dsneddon:irc        |  @dxs:twitter
>
>
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