In hybrid cloud environments, network design is one of the most important and fundamental parts. It is a basic requirement for any type of Kubernetes cluster, whether it is a single-zone cluster or a multi-regional cluster. In this article, we will explain how to design a network for a hybrid cloud Kubernetes cluster.

Key Considerations for Network Design:

• Ensure reliable and secure connections between on-premises and cloud data centers.


• Optimize network latency


• Plan IP address ranges to avoid conflicts between data centers


• Use firewalls to control traffic between networks

Communication inside the cluster

Node-to-node:

All nodes in the cluster must have connectivity to each other. Control plane nodes must have access to the kubelet on each node. Nodes must have access to the control plane nodes. If you going to use Kubernetes Admission Controllers, the control plane need access to the pods too.

Pod-to-pod:

Pods must have access to the control plane nodes to reach the Kubernetes API. Monitoring systems must have access to all nodes to collect metrics and logs. Pods must be able to communicate with other pods within the same cluster. In many cases, pods also need access to the internet and cloud provider services. The latency between nodes, zones, and regions is a crucial factor. Application deployments should be aware of the network topology to optimize performance. Furthermore, when regions are located in different cloud providers, communication can become unstable and slower. Proper planning and optimization are required to address these challenges.

In summary, all pods and nodes must have connectivity with each other. A hybrid Kubernetes cluster has multiple zones and regions, adding more complexity to network design.

Network design

Hardware or Saas VPN

The well-known cloud providers offer VPN services. VPN links can be established between zones and regions, enabling secure and stable connections across different geographical locations. VPN connections can be hardware-based or software-based, depending on the infrastructure requirements. VPN helps in maintaining data security and encryption during transmission.

The latency between cloud providers is very low, and bandwidth is predictable. This link uses dedicated fiber optic cables, which are more reliable than the public internet.

Mesh network

A mesh network is a network topology where each node establishes a connection with every other node. Unlike traditional hierarchical networks, mesh networks are decentralized, allowing every node to cooperate in data distribution and routing. All connections are encrypted and secure.