<p>How to achieve internal service to service communication in Anthos multiple clusters Example
service A deployed in GKE cluster and service B deployed in AKS cluster, here how we can call service A from service B (internally) ?</p>

<p>As suggested by @Harsh Manver you can <a href="https://cloud.google.com/service-mesh/docs/unified-install/off-gcp-multi-cluster-setup" rel="nofollow noreferrer">set up a multi cluster mesh outside Google Cloud</a> to achieve internal service to service communication in Anthos multiple clusters.</p>
<p>As mentioned in the <a href="https://cloud.google.com/service-mesh/docs/unified-install/multi-cloud-hybrid-mesh" rel="nofollow noreferrer">document</a>:</p>
<blockquote>
<p>The cluster's Kubernetes control plane address and the gateway address
need to be reachable from every cluster in the mesh. The Google Cloud
project in which GKE clusters are located should be allowed to create
external load balancing types.</p>
<p>We recommend that you use authorized networks and VPC firewall rules
to restrict the access and  ensure traffic should not exposed to
public internet</p>
</blockquote>
