When to Use BGP, VXLAN, or IP-in-IP: A Practical Guide for Kubernetes Networking

The Cost of a Mismatched Network Mode A Technical Breakdown of Networking Modes VXLAN (Virtual Extensible LAN) IP-in-IP BGP (Border Gateway Protocol) Decision Matrix Simplifying Operations Across Network Modes Final Verdict: Selecting the Right Networking Mode for Your Workload Ready to Simplify Kubernetes Networking? When deploying a Kubernetes cluster, a critical architectural decision is how pods on different nodes communicate. The choice of networking mode directly impacts performance, scalability, and operational overhead. Selecting the wrong mode for your environment can lead to persistent performance issues, troubleshooting complexity, and scalability bottlenecks. The core problem is that pod IPs are virtual. The underlying physical or cloud network has no native awareness of how to route traffic to a pod’s IP address, like 10.244.1.5 It only knows how to route traffic between the nodes themselves. This gap is precisely what the Container Network Interface (CNI) must bridge. 10.244.1.5 The CNI employs two primary methods to solve this problem: Overlay Networking (Encapsulation): This method wraps a pod’s packet inside another packet that the underlying network understands. The outer packet is addressed between nodes, effectively creating a tunnel. VXLAN and IP-in-IP are common encapsulation protocols. Underlay Networking (Routing): This method teaches the network fabric itself how to route traffic directly to pods. It uses a routing protocol like BGP to advertise pod IP routes to the physical network, making pods routable without encapsulation. This guide dives into the technical differences of these options to help you select the right mode for your environment.