r</figcaption></figure><p>Mesh admins can expand the service mesh to multiple clusters, which are managed by the same Istiod running in the external cluster. None of the mesh clusters are <span class=term data-title="Primary Cluster" data-body='<p>A primary cluster is a <a href="/docs/reference/glossary/#cluster">cluster</a> with a
<a href="/docs/reference/glossary/#control-plane">control plane</a>. A single
<a href="/docs/reference/glossary/#service-mesh">mesh</a> can have more than
one primary cluster for