Bug 2013820

Description of problem:
I am trying to validate Ironic in the Overcloud with OVN and routed networking topology.
I am unable to create neutron segments without openstack removing the dhcp servers created under dhcp-agent

Here is a runlog:

(tigerlab-central) [stack@dcn-undercloud ~]$ openstack network segment set --name segment0 ff17ee9d-04f9-47a7-8d55-a02097b1bbad                                                                                                              
(tigerlab-central) [stack@dcn-undercloud ~]$ openstack port list --network oc_provisioning --device-owner network:dhcp -c "Fixed IP Addresses" -c "ID"                                                                                       
+----------------------------------------------------------------------------+--------------------------------------+
| Fixed IP Addresses                                                         | ID                                   |
+----------------------------------------------------------------------------+--------------------------------------+
| ip_address='10.9.64.236', subnet_id='55389619-ecc0-4605-9830-e3035dc4f9a1' | 3679e2ba-59e5-4f5b-9166-c23fb191bb55 |
| ip_address='10.9.64.239', subnet_id='55389619-ecc0-4605-9830-e3035dc4f9a1' | 3c6ea9c9-7283-45ec-8b5b-17969c7dc5e2 |
| ip_address='10.9.64.238', subnet_id='55389619-ecc0-4605-9830-e3035dc4f9a1' | 66b635e6-dd0c-4f5c-8507-9ec183e221dc |
| ip_address='10.9.64.242', subnet_id='55389619-ecc0-4605-9830-e3035dc4f9a1' | 674896b2-0f02-4b22-8e70-19608fe20102 |
| ip_address='10.9.64.241', subnet_id='55389619-ecc0-4605-9830-e3035dc4f9a1' | 7a40184b-4e4d-4e76-9acb-cd1e8cbb3d93 |
| ip_address='10.9.64.237', subnet_id='55389619-ecc0-4605-9830-e3035dc4f9a1' | def6e40c-bda5-418f-97ce-4e2265b1dcc1 |
| ip_address='10.9.64.240', subnet_id='55389619-ecc0-4605-9830-e3035dc4f9a1' | e36d8095-1379-49d9-9a1c-0f197bf86f39 |
+----------------------------------------------------------------------------+--------------------------------------+
(tigerlab-central) [stack@dcn-undercloud ~]$ openstack subnet set --network-segment segment0 oc_provisioning-seg0                                                                                                                            
(tigerlab-central) [stack@dcn-undercloud ~]$ openstack port list --network oc_provisioning --device-owner network:dhcp -c "Fixed IP Addresses" -c "ID"                                                                                       
+----------------------------------------------------------------------------+--------------------------------------+
| Fixed IP Addresses                                                         | ID                                   |
+----------------------------------------------------------------------------+--------------------------------------+
| ip_address='10.9.64.238', subnet_id='55389619-ecc0-4605-9830-e3035dc4f9a1' | 66b635e6-dd0c-4f5c-8507-9ec183e221dc |
+----------------------------------------------------------------------------+--------------------------------------+
As you can see after assigning the network segment all my dhcp servers disappearing.

Without the dhcp I am not able to forward the Ironic DHCP traffic for cleaning and provisioning.



Version-Release number of selected component (if applicable):
cat /etc/rhosp-release 
Red Hat OpenStack Platform release 16.2.0 GA (Train)


How reproducible:
I'll include below my deployment command and relevant template files.


Steps to Reproduce:
1. Deploy Overcloud with Ironic and OVN
2. Attempt to create ironic networks/segments to accommodate routed networking
3.

Actual results:
DHCP servers get removed

Expected results:
Ability to match OVS behavior where DHCP servers don't get removed

Additional info:
Exactly same topology with OVS works fine, so the problem is isolated to OVN
Ironic with OVN seems to work as long as neutron-dhcp-agent is included and flat network is being used. The problem only occurs when using routed networking

Commands used to create those segmented networks:

#!/bin/bash

source ~/tigerlab-centralrc

openstack network create oc_provisioning --provider-network-type flat --provider-physical-network baremetal --share --external --mtu 1500
SID=$(openstack network segment list --network oc_provisioning -c ID -f value)
openstack network segment set --name segment0 ${SID}
openstack network segment create --network oc_provisioning --physical-network segment1 --network-type flat segment1
openstack network segment create --network oc_provisioning --physical-network segment2 --network-type flat segment2
openstack subnet create --network-segment segment0 --network oc_provisioning --subnet-range 10.9.64.192/26 --dhcp --allocation-pool start=10.9.64.236,end=10.9.64.254 --gateway=10.9.64.193 oc_provisioning-seg0
openstack subnet create --network-segment segment1 --network oc_provisioning --subnet-range 10.9.66.192/26 --dhcp --allocation-pool start=10.9.66.236,end=10.9.66.254 --gateway=10.9.66.193 oc_provisioning-seg1
openstack subnet create --network-segment segment2 --network oc_provisioning --subnet-range 10.9.70.192/26 --dhcp --allocation-pool start=10.9.70.236,end=10.9.70.254 --gateway=10.9.70.193 oc_provisioning-seg2

I'll include relevant templates and sosreport below