Chapter 2. Migrating from OpenShift SDN network plugin to OVN-Kubernetes network plugin

Procedure

1. Create a JSON file with the following content:

   {
     "type": "sdnToOvn"
   }

   • Optional: Within the JSON file, you can configure internal subnets using any or all of the options join, masquerade, and transit, along with a single CIDR per option, as shown in the following example:

     {
       "type": "sdnToOvn",
       "sdn_to_ovn": {
         "transit_ipv4": "192.168.255.0/24",
         "join_ipv4": "192.168.255.0/24",
         "masquerade_ipv4": "192.168.255.0/24"
       }
     }

     Note

     OVN-Kubernetes reserves the following IP address ranges:

     100.64.0.0/16. This IP address range is used for the internalJoinSubnet parameter of OVN-Kubernetes by default.

     100.88.0.0/16. This IP address range is used for the internalTransSwitchSubnet parameter of OVN-Kubernetes by default.

     If these IP addresses have been used by OpenShift SDN or any external networks that might communicate with this cluster, you must patch them to use a different IP address range before initiating the limited live migration. For more information, see Patching OVN-Kubernetes address ranges in the Additional resources section.

2. To initiate the migration, run the following post request in a terminal window:

   $ ocm post /api/clusters_mgmt/v1/clusters/{cluster_id}/migrations 

   1

   
     --body=myjsonfile.json 

   2

   1

   Replace {cluster_id} with the ID of the cluster you want to migrate to the OVN-Kubernetes network plugin.

   2

   Replace myjsonfile.json with the name of the JSON file you created in the previous step.

   Example output

   {
     "kind": "ClusterMigration",
     "href": "/api/clusters_mgmt/v1/clusters/2gnts65ra30sclb114p8qdc26g5c8o3e/migrations/2gois8j244rs0qrfu9ti2o790jssgh9i",
     "id": "7sois8j244rs0qrhu9ti2o790jssgh9i",
     "cluster_id": "2gnts65ra30sclb114p8qdc26g5c8o3e",
     "type": "sdnToOvn",
     "state": {
       "value": "scheduled",
       "description": ""
     },
     "sdn_to_ovn": {
       "transit_ipv4": "100.65.0.0/16",
       "join_ipv4": "100.66.0.0/16"
     },
     "creation_timestamp": "2025-02-05T14:56:34.878467542Z",
     "updated_timestamp": "2025-02-05T14:56:34.878467542Z"
   }