Hi Sean, I just wanted to respond with my own opinions on things here, comments below. On 3/3/25 9:21 AM, Sean Mooney wrote:
On 03/03/2025 13:50, Ricardo Cano wrote:
Hello openstack-discuss,
With the removal of the linuxbridge mechanism driver, has anyone successfully completed an in-place migrationfrom LinuxBridge to OVN? I did come across this https://www.jimmdenton.com/migrating-lxb-to-ovn/ and that looks good as a one-shoit while biting the bullet and taking a full outage. However, I was wondering if it was possible to run lxb and ovn side-by-side and cut them over, say one network at a time.
This particular deployment was stood up using openstack-ansible back in the rocky days (now running antelope) and it appears that openstack ansible's default was lxb up until Zed.
that is likely because the official default backend of neutron was Linux bridge
When we changed the name from Quantum to Neutron (2013), the default backend in devstack was changed to Openvswitch. In 2021 the default was changed to OVN (twice if you count the revert/resubmit). We agreed at the time OVN was the recommended architecture going forward and have kept moving in that direction since then. There are less core reviewers and we can only support a limited number of things, so there will be these "burn the ships" moments in our future I can imagine.
in the install guide since it creation until it was marked experimental by neutron
We have been notoriously slow at updating the in-tree install guides, but we changed it in 2023.1 to Openvswitch since it was a simple fix. We'll update it again, but they are generally not widely used by anyone doing an enterprise install.
our devstack ci jobs defaulted to ovs for most of openstack lifetime but
ovs only became the offical default backend when linux bridge was marked experimental
https://docs.openstack.org/neutron/latest/install/controller-install-ubuntu....
ovn is still not the default in the docs or in most installers even if that is what we use in the devstack jobs by default.
I would disagree. Both the Red Hat and Ubuntu installers have defaulted to OVN since Yoga (or before), and afaik only support OVN from 2024.1 onward. I have never seen a customer deployment using Linuxbridge, and have only seen 2 using ML2/OVS (and it was the same customer). There was a recent question on the list about an OVN install failure that showed some issues in the docs, the sender is submitting a bug and working on an update based on their experience. I am glad the operator community picked-up the work of helping with the transition to OVN, and our goal now is to make sure we can help with any issues that arise, either in the docs or code, to make that successful. -Brian
its an add on alretrnive procedure for "advanced users only"
https://docs.openstack.org/neutron/latest/install/ovn/manual_install.html
so openstack-ansibel was jsut followign the documented defautl backend.
kolla, devstack and tripleo diverged from that.
Any suggestions or recommendations on the best path forward?
Also, will the dynamic routing agent work with ovn
i believe ovn does DVR differently without a requirement form the agent.
i.e. if the vm has a floating ip i belive ovn can route that traffic locally to the internet form the compute without
needing to use a central gateway but ill admit i could be missremebering that i have not looked at it in detail in a number of years.
https://docs.openstack.org/neutron/latest/ovn/gaps.html
"""
*
Floating IP Port Forwarding in provider networks and with distributed routing
Currently, when provider network types like |vlan| or |flat| are plugged to a router as internal networks while the |enable_distributed_floating_ip| configuration option is enabled, Floating IP port forwardings which are using such router will not work properly. Due to an incompatible setting of the router to make traffic in the vlan/flat networks to be distributed but port forwardings are always centralized in ML2/OVN backend. This is being reported in [11] <https://docs.openstack.org/neutron/latest/ovn/gaps.html#id23>.
[11] https://bugs.launchpad.net/neutron/+bug/2028846 <https://bugs.launchpad.net/neutron/+bug/2028846>
"""