pods in Istio service mesh.</li><li><code>ambient: L4</code>: Default ambient mode with the <span class=term data-title="Secure L4 Overlay" data-body='<p>The term &amp;ldquo;secure overlay&amp;rdquo; or &amp;ldquo;secure L4 overlay&amp;rdquo; is used to collectively describe the set of L4 networking functions implemented in an ambient mesh via the ztunnel proxy. At the transport layer, this is implemented via an HTTP CONNECT-based traffic tunneling protocol called <a href="/docs/reference/glossary/#hbone">H