Bug 1511493

Description of problem:
For OVN deployments, in order for any node (be it compute or controller) to provide external connectivity to the tenant traffic, ovn-controller service should be running and the ovn-bridge-mappings (eg. OVNBridgeMappings=datacentre:br-ex) should be defined. Tripleo when deployed with OVN does it, but it does on all the nodes where (ovn-controller service is enabled) even if those nodes do not have external connectivity. Neutron ML2 OVN driver considers all the nodes configured with "ovn-bridge-mappings" as candidates and could schedule on any node. This will cause problems on deployments where only controller (or network) nodes provide external connectivity.

Version-Release number of selected component (if applicable):
(overcloud) [stack@undercloud-0 ~]$ cat /etc/yum.repos.d/latest-installed 
12   -p 2017-11-03.4
(overcloud) [stack@undercloud-0 ~]$ rpm -qa |grep director
rhosp-director-images-ipa-12.0-20171103.1.el7ost.noarch
rhosp-director-images-12.0-20171103.1.el7ost.noarch
(overcloud) [stack@undercloud-0 ~]$ rpm -qa |grep triple
python-tripleoclient-7.3.2-2.el7ost.noarch
openstack-tripleo-image-elements-7.0.1-0.20171020101256.2e61e31.el7ost.noarch
openstack-tripleo-heat-templates-7.0.3-0.20171024200823.el7ost.noarch
openstack-tripleo-common-containers-7.6.3-0.20171028055750.el7ost.noarch
openstack-tripleo-puppet-elements-7.0.1-0.20171020122223.82d7e6c.el7ost.noarch
openstack-tripleo-common-7.6.3-0.20171028055750.el7ost.noarch
openstack-tripleo-ui-7.4.2-2.el7ost.noarch
openstack-tripleo-validations-7.4.1-2.el7ost.noarch
puppet-tripleo-7.4.3-0.20171025110206.el7ost.noarch


How reproducible:
always

Steps to Reproduce:
1.deploy ovn HA setup
2.create router and set gateway 

3. check connectivity to the router 

Actual results:
no connectivity
Expected results:


Additional info: