Flannel comes from CoreOS and is an etcd-backed overlay. Flannel gives a full subnet to each host/node, enabling a similar pattern to the Kubernetes practice of a routable IP per pod or group of containers. Flannel includes an in-kernel VXLAN encapsulation mode for better performance and has an experimental multi-network mode similar to the overlay Docker plugin. For more information, visit https://github.com/coreos/flannel.