Update neutron-helm-overrides.yaml

Enable FDB learning for OVN as part of https://review.opendev.org/c/openstack/neutron/+/877675 which is observed once port security is disabled

Author: bjoernt

base-helm-configs/neutron/neutron-helm-overrides.yaml

@@ -246,6 +246,12 @@ conf:
       ovn_l3_scheduler: leastloaded
       ovn_nb_connection: "tcp:127.0.0.1:6641"
       ovn_sb_connection: "tcp:127.0.0.1:6642"
+
+      # Fix disabled port security on provider network
+      # https://review.opendev.org/c/openstack/neutron/+/877675     
+      localnet_learn_fdb: true
+      fdb_age_threshold: 900
+      fdb_removal_limit: 2048
     metadata_rate_limiting:
       rate_limit_enabled: true
       ip_versions: 4

releasenotes/notes/neutron-ovn-fdb-learning-fedb1a56b321ec8b.yaml

@@ -0,0 +1,6 @@
+---
+upgrade:
+  - |
+    Neutron OVN setting `localnet_learn_fdb` is now enabled to avoid flodding
+    on provider networks once port security is disabled.
+    See https://launchpad.net/bugs/2012069