Pod namespaces

By default, Pods are non-isolated, and they accept traffic from any source including other Pods present within the cluster. Pods become isolated by having a NetworkPolicy that selects them. Once there is any NetworkPolicy in a namespace selecting a particular pod, that pod will reject any connections that are not allowed by any NetworkPolicy. Network policies affect only Pod-to-Pod communication and do not affect service-to-service traffic directly. Network policies use labels specified within the PodSelector attribute of their definition to select the Pods on which the associated traffic rules will be enforced.

https://docs.robin.io/platform/latest/manage_network.html?highlight=interface#how-it-works