k8wiz
Cilium
Hard
Networking

What does Direct Server Return (DSR) mode change in Cilium's NodePort and LoadBalancer handling?

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Show answer and explanation

Answer: Backends reply to the client directly, not via the ingress node

Explanation

In the default SNAT mode, a node that forwards a request to a backend on another node rewrites the source address, so the reply has to come back through it. In DSR mode the forwarding node keeps the client address and passes the service address along with the packet, so the backend can reply to the client directly. That saves a hop and lets the backend see the client IP.