bernetes behavior of all
services being able to communicate with other.</p><p>External services are services which are not part of your platform i.e. services
which are outside of the mesh. For external services, Istio provides two
options, first to block all external service access (enabled by setting
<code>global.outboundTrafficPolicy.mode</code> to <code>REGISTRY_ONLY</code>) and
second to allow all access to external service (enabled by setting
<code>global.outboundTrafficPolicy.mode</code> to <code>ALL