When running Kubernetes there are multiple options for the configuration of how pods can communicate. Kubernetes requirements are that pods on a node can communicate with all pods on all nodes without Network Address Translation (NAT). Agents on a node (for example, system daemons, kubelet) can communicate with all pods on that node, and pods in the host network of a node can communicate with all pods on all nodes without NAT. For further details, refer to the following Kubernetes page: Cluster Networking.

There are several ways to implement these and it varies based on the Container Network Interface (CNI) plugins used, cloud provider integrations, or any Border Gateway Protocol (BGP) peering with the physical network in use.

If the pods are routable from outside the network there is no requirement for outbound Secure Network Address Translation (SNAT) and pods can be accessed directly without using Kubernetes Services. The disadvantage is that the IP addresses used must be reserved for pod use.