In this chapter, we learnt how Docker containers communicate across multiple hosts using different networking options such as Weave, OVS, and Flannel. Pipework uses the legacy Linux bridge, Weave creates a virtual network, OVS uses GRE tunneling technology, and Flannel provides a separate subnet to each host in order to connect containers to multiple hosts. Some of the implementations, such as Pipework, are legacy and will become obsolete over a period of time, while others are designed to be used in the context of specific OSes, such as Flannel with CoreOS.

The following diagram shows a basic comparison of Docker networking options:

In the next chapter, we will discuss how Docker containers are networked when using frameworks such as Kubernetes, Docker Swarm, and Mesosphere.