UDP is not fully stateless

BRE-ISNIC / bre-doh-analysis

To DoH or not to DoH?

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UDP is not fully stateless #2

Closed bortzmeyer closed 4 years ago

bortzmeyer commented 4 years ago

"stateless UDP" Be careful, UDP cannot be completely stateless since you have to remember the path MTU to the target (specially for IPv6). On FreeBSD at least, implementation of UDP uses state.

BRE-ISNIC commented 4 years ago

UDP itself is stateless.

The fact that some implementations may add state as an optimization or to facilitate the more common use-cases doesn't really change that. And it certainly doesn't change the overall analysis, which is that TCP requires both more resources and more round-trips to communicate.