Edge cases exist in which network restrictions prevent modern clusters from connecting to other clusters involved in the migration. For example, when migrating from an OpenShift Container Platform 3.11 cluster on premises to a modern OpenShift Container Platform cluster in the cloud, where the modern cluster cannot connect to the OpenShift Container Platform 3.11 cluster.

With MTC 1.7, if one of the remote clusters is unable to communicate with the control cluster because of network restrictions, use the crane tunnel-api command.

With the stable MTC release, although you should always designate the most modern cluster as the control cluster, in this specific case it is possible to designate the legacy cluster as the control cluster and push workloads to the remote cluster.