Comment by nyrikki
17 hours ago
> Note: For simplicity, we’ll focus on Layer 7 (HTTP) reverse proxy.
Layer 4 proxies are a very specific sometimes food that most people should actively avoid until they need it because of the tradeoffs.
DSR is layer 4, and not in scope of this post.
Your comment, to me, only points out that the OSI layer model is nonsense. Envoy in DSR mode routes traffic based on application features, at "layer 7".
Envoy calls it Layer 4
https://blog.envoyproxy.io/introduction-to-modern-network-lo...
That's fair. Of course that post also calls the OSI model "unfortunate" and "a poor approximation".
The model itself isn’t nonsense because it’s not a model of load balancers; it’s a model of network protocols. Load balancers might handle multiple levels of the stack for the same traffic, but so does any other networked program, eg handling cross-domain redirects.