An overlay network allows network devices to communicate across an underlying network (referred to as the underlay) without the underlay network having any knowledge of the devices connected to the overlay network.

There are several common overlay network types that can be used such as Flannel Calico and Weave Net. Typically, when using an overlay network, pods are assigned with an address from a set of addresses assigned to the overlay network and this is different from the Host Network in which the Node's IP addresses are from.

In most cases when using an overlay network, it is typical that pods are not routable.