Open Stack

Folks,

I have deployed openstack using ML2/OVN on 1 controller and 2 compute
nodes so far everything is working fine, when i configured router it
by default used L3HA and i can see active-backup router on both
compute nodes. currently my all SNAT traffic going out using compute-1

I don't want bottleneck in network so i am looking for DVR deployment
and after reading i found tenant VLAN doesn't support DVR
https://bugzilla.redhat.com/show_bug.cgi?id=1704596

After doing more research i found that if i set manually external_mac
using the following command then my vm using local compute node to
send traffic in/out just like DVR instead of centralized design.


root at os-infra-1-neutron-ovn-northd-container-24eea9c2:~# ovn-nbctl
find NAT type=dnat_and_snat
_uuid               : 99bdd866-01ed-425d-853b-9362ae8572c9
external_ids        : {"neutron:fip_external_mac"="fa:16:3e:2d:7e:fa",
"neutron:fip_id"="025a912a-c0ee-4f36-98ad-8992bd825cfc",
"neutron:fip_network_id"="9cccf39d-edba-4069-91ef-5f30afbb6604",
"neutron:fip_port_id"="70ad361a-b42e-403b-a5c1-4ee39ddf5e31",
"neutron:revision_number"="6",
"neutron:router_name"=neutron-8af10b06-c8de-4166-9ab1-ca2f775b08a8}
external_ip         : "10.40.255.10"
external_mac        : []
logical_ip          : "172.168.0.164"
logical_port        : "70ad361a-b42e-403b-a5c1-4ee39ddf5e31"
options             : {}
type                : dnat_and_snat

_uuid               : c438e7be-5ff4-472e-b053-8d6ed74cd4dc
external_ids        : {"neutron:fip_external_mac"="fa:16:3e:f5:9f:f0",
"neutron:fip_id"="31e8cb44-0acd-453b-a4e6-39f6ab3a6da4",
"neutron:fip_network_id"="9cccf39d-edba-4069-91ef-5f30afbb6604",
"neutron:fip_port_id"="44a677c5-86ff-4b6b-a046-54e79f79c4cd",
"neutron:revision_number"="2",
"neutron:router_name"=neutron-8af10b06-c8de-4166-9ab1-ca2f775b08a8}
external_ip         : "10.40.255.5"
external_mac        : []
logical_ip          : "172.168.0.67"
logical_port        : "44a677c5-86ff-4b6b-a046-54e79f79c4cd"
options             : {}
type                : dnat_and_snat


This is how i set external mac from
fip_external_mac"="fa:16:3e:2d:7e:fa" in above command.

ovn-nbctl set NAT 99bdd866-01ed-425d-853b-9362ae8572c9
external_mac="fa\:16\:3e\:2d\:7e\:fa"

How do i make this behavior default for every single VM, i don't want
to do this manually to set the external mac address of each FIP?