Hello Chandler,

Thank you for contacting AWS support. My name is Sypher and I will be helping you and your case today. According to your description, I understand you want to ask that is there have any flaws of creating two EKS cluster in one VPC. If I misunderstand your question, please feel free to correct me. Generally speak, there won’t have any flaws if you deploy two EKS clusters in one VPC. The only thing currently it might need to be noticed is the IP address allocate problem. As you might know, Amazon EKS supports native VPC networking via the Amazon VPC Container Network Interface (CNI) plugin for Kubernetes [1]. Using this CNI plugin allows Kubernetes pods to have the same IP address inside the pod as they do on the VPC network. Thus, it means that each pod will allocate one private IP from your VPC. If each EKS cluster might deploy lots of pods in the future, you might need to consider the IP insufficient problem. After I reviewed your EKS Clusters’ VPC, each subnet still have more that 8000 IPs can use. Hence, I think currently there have no issue you need to worry. However, if you have some questions or encountered the issue in the future, please do not hesitate to reach out us again. We are willing to help you solve the problem.

综上，为验证我的疑问：一个VPC，创建多个EKS集群，选择相同的子网，是否会有冲突。因此我动手试了一发。如我推测，AWS的EKS 简直棒呆了！由于EKS的CNI插件，使得PODS的网络接口，对应一个VPC中的一个私有ip（network interface）。这个network interface上的安全组规则，实现了网络的互通。