On 10/6/26 5:00 PM, Matteo Perin via dev wrote: > Hi all, > > Recently, while investigating some scaling issues on cloud deployments we > found out that in ovs versions prior to 3.5 the flow tables IPv6 addresses > and L4 ports prefix matching must be set manually. This caused some > confusion and temporary performance loss since it makes new deployments > just slightly more annoying from an Ops perspective. > > This minor inconvenience was solved in commit 2af7cef (ofproto: Enable > address prefix tracking for IPv6 by default.) which sets these values by > default. This change actually requires the prefix expansion in 4394f72 > (classifier: > Increase the maximum number of prefixes (tries).) which is already > backported in branch 3.3. > > I was wondering if this default behavior mismatch between versions 3.3 and > 3.5 is intended and, if not, if backporting 2af7cef to branch-3.3 would be > a possibility. > > This will minimize the chances of misconfigurations and related flow table > explosions when using IPv6. Hi, Matteo. The mismatch is intended. The solution for IPv6 flow explosion was developed after 3.3 was released and the solution was intentionally split into a set with two patches: 1. Allow manually configuring 4 prefixes at the same time. 2. Enable both ipv4 and ipv6 sets of prefixes by default at the same time.
The idea was to backport the first, so users can solve the problem if they hit it, but avoid changing the default behavior as it may come with a bit of a performance penalty to users that do not have ipv6 in their setup, as processing extra prefix tries takes more time and space. At this point in time, I don't think we should backport the change to 3.3. 3.3 is our old LTS which will hit its EoL in just 4 months. So, I'd argue that no new setups should be deployed with OVS 3.3 moving forward and all the existing setups should consider moving to 3.7. Besides, at least for OVN users it should be less of a problem, as ovn-controller would enable all the prefixes by default, if the are available. Best regards, Ilya Maximets. _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
