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RFC2119 Upper Case Syntax for rfc2460bis

Bob Hinden <bob.hinden@gmail.com> Tue, 20 October 2015 21:58 UTC

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From: Bob Hinden <bob.hinden@gmail.com>
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Subject: RFC2119 Upper Case Syntax for rfc2460bis
Date: Tue, 20 Oct 2015 14:58:48 -0700
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There has been several suggestions on the list that rfc2460bis (and I assume rfc4291bis) should reference RFC2119 and use the Upper cast SHOULD, MUST, etc. language.  RFC2460 and RFC4291 were written before this was commonplace.

Formally RFC2119 is not required to be used, nor does it require upper case language.  It’s use is a SHOULD :-)

RFC2460 and RFC4291 both use similar words, that is should, must, recommend, may etc, but not in upper case.  IPv6 is widely implemented and I do not think that there is any evidence that the lack of use of RFC2119 language has been a hinderance to IPv6 implementations.  Nor do any of the RFCs that update fix this kind of problem.

My view is that we should not introduce RFC2119 style of language into rfc2460bis and rfc4291bis.  I have several reasons for this.

I think we should be making as few changes a possible in order to move these specification to Internet Standard. The more changes we make that are not required to meet the requirements in RFC6410, the greater the risk of breaking interoperability.

While I don’t think there would be a risk with many of the changes from “should” to “SHOULD” etc., there are more than a few cases where the language is declarative, but the RFC2119 words are not used.  While the meaning of this current text is clear, if we change all of the lower case should/must language to upper case, some may argue that because the text that doesn’t use these words they are not required to implement.  If we try to rewrite all of the declarative text to use upper case “SHOULD/MUST” we may well break interoperability.

Overall I think that moving to RFC2119 style has the potential to create problems where they don’t exist today.

Bob

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