Load Balancing & WebSockets (L4 vs L7)

Introduction When you build a standard web app, load balancing is usually straightforward because every request is independent. You just spread the traffic around. But once you introduce WebSockets, everything changes. You are no longer dealing with quick requests. You are managing a persistent pipe that might stay open for hours. The first thing to understand is that WebSockets can work on either Layer 4 or Layer 7. There is no hard rule requiring one over the other. Every load balancer can pass a pocket of bits through. The difference is entirely in how the device treats the connection once it is established. How Layer 4 handles the traffic Since WebSockets are built on top of TCP, a Layer 4 load balancer can handle them perfectly. Think of this balancer as a high speed postman who only reads the house number on the envelope. He doesn't know he is routing WebSockets or HTTP. He just sees a raw TCP connection request on a specific port and blindly forwards that stream to a backend ser