Open Stack

On Sun, Sep 10, 2023 at 4:13 AM Satish Patel <satish.txt at gmail.com> wrote:
>
> Folks,
>
> I am trying to set an availability zone for OVN because skyline UI has a mandatory requirement to have an availability zone otherwise you are not allowed to create a network from skyline GUI.
>
> for OVN based deployment only option to set AZ is in ovn-cms-options
>
> # ovs-vsctl set open_vswitch . external_ids:ovn-cms-options="enable-chassis-as-gw,availability-zones=az-0"
>
> Question:
>
> 1. How do I configure in kolla-ansible to override or set ovn-cms-options on only gateway chassis?
> 2. How does AZ work in OVN because OVN is anyway distributed as per documents, What if I just give foobar AZ name to meet Skyline requirement? Is it going to break anything?

Answering 2.

There are two types of availability zones in Neutron: Routers and Networks.

For Routers, ML2/OVN will schedule the gateway router ports onto the
nodes belonging to the availability zones provided by the
--availability-zone-hint parameter, for example:

$ openstack router create --availability-zone-hint az-0
--availability-zone-hint az-1 router-0

For Networks. Since DHCP is distributed in ML2/OVN as you pointed out
we do not care about scheduling DHCP agents (like ML2/OVS). But there
are few cases for Network AZ in ML2/OVN that are related to external
ports [0], these are ports that live on a different host than the
instance to address use cases such as SR-IOV and Baremetal with
ML2/OVN.

You can read more ML2/OVN AZs here:
https://docs.openstack.org/neutron/latest/admin/ovn/availability_zones.html

[0] https://docs.openstack.org/neutron/latest/admin/ovn/external_ports.html

Cheers,
Lucas