１、DockOne技术分享（十八）：一篇文章带你了解Flannel
http://dockone.io/article/618
２、理解Kubernetes网络之flannel网络
http://tonybai.com/2017/01/17/understanding-flannel-network-for-kubernetes/
3、使用Kubeadm安装Kubernetes
http://tonybai.com/2016/12/30/install-kubernetes-on-ubuntu-with-kubeadm/
4、flannel troubleshooting
https://github.com/coreos/flannel/blob/master/Documentation/troubleshooting.md
5、flannel cni plugin
https://github.com/containernetworking/plugins/tree/master/plugins/meta/flannel