Istio and Network policy

I am not sure how Istio and Network policy can work together…I read in some articles we can use Network policy at Layer4. But if we have already enabled Authorization policy in Istio in Layer7, why should we also create network policy for the same pods to interact with other pods?

Is there any sample on this? sample documentation

You can apply both NetworkPolicy and Istio AuthorizationPolicy for higher security (defense in depth) because they work on different layer and have very different enforcement mechanism.

You can refer to the standard k8s NetworkPolicy for its usage.