> On Jun 15, 2017, at 6:54 AM, John C Klensin <john-ietf@xxxxxxx> wrote: > > I suggest that one of the reasons the > Internet has been successful is precisely because of sensible > application of the robustness principle. Not only do things > mostly work, or at least produce sensible error messages or > warnings rather than blowing up, in the presence of small > deviations or errors, but (in recent years at least in theory) > it avoids out having to spend extra years in standards > development while we analyze every possible error and edge case > and specify what should happen. Instead, when appropriate, we > get to say, when appropriate, "this is the conforming behavior, > if you don't conform, the standard has nothing to say to you, > but you should not depend on its working". The robustness > principle is important guidance for those edge cases. +1 Further, testing for all those edge cases becomes itself a performance burden on operational code, amplifying the leverage of a DOS attack based on all that excess validation. The Postel principle helps make achieving the balance between usefulness and correctness tractable. Joe