Description of problem: OVN migration OSP 16.1 introduced an ML2-OVN mechanism driver that adds capabilities for SDN overlays on top of OVS among other benefits. Going forward Red Hat's strategy is to deprecate the ML2-OVS mechanism driver. Starting in OSP 18.0, ML2-OVS will not be supported and the ML2-OVS functionality will be removed. The transition from ML2-OVS to ML2-OVN can be divided into 2 pillars - (1) ML2-OVS <-> ML2-OVN feature parity (2) ML2-OVS to ML2-OVN migration. ML2-OVN migration involves validating the features and the data path types supported Use Case: Telco Service Providers deploy OpenStack for NFV workloads using fast datapath types such as OVS-DPDK, SR-IOV, and HWOL. Moving to OVN should not disrupt their current operations or feature capabilities as compared to ML2-OVS. Additionally, Telco customers have the requirement of completing the OVN migration of the large-scale cluster (up to 250 nodes) within the maintenance window of fewer than 10 hours and exiting the maintenance window in an operational state. The following OVN migration paths are available for the customers: (1) 16.1 ML2-OVS > 16.2 ML2-OVS > 17.1 ML2-OVS > 17.1 ML2-OVN (2) 16.2 ML2-OVS > 17.1 ML2-OVS > 17.1 ML2-OVN (3) 16.2 ML2-OVS > 16.2 ML2-OVN (4) 17.1 ML2-OVS > 17.1 ML2-OVN Refer to https://issues.redhat.com/browse/OSP-21921 for more details Requirement Details MVP Priority EPIC OVN migration for (4) migration path must work for test topology with HWOL, SR-IOV, and OVS-DPDK with no blocking errors Yes 1 Validate data plane connectivity and operation pos OVN migration for the NFV workloads and data path types Yes 1 Validate HWOL with VLAN trunk ports Yes 1 CI test runs for HWOL, SR-IOV and OVS-DPDK Yes 1 Support for batch migration where OVN migration can be done for a batch of nodes that do not have the need to communicate with other nodes in the cluster that are outside the batch No 3 Revert support from ML2-OVN to ML2-OVS on failure (all nodes in the cluster) Yes 1 Revert support from ML2-OVN to ML2-OVS on failure (all nodes in the batch) No 3 Recovery from a node crash during OVN migration Yes 1 Version-Release number of selected component (if applicable): How reproducible: Steps to Reproduce: 1. 2. 3. Actual results: Expected results: Additional info: