Re: [arch-d] deprecating Postel's principle- considered harmful

Hi Deborah,

On 08-May-19 07:17, BRUNGARD, DEBORAH A wrote:
> Not seeing much discussion on this document on the lists, I put a twist on the title-
> 
> I find the document (as currently written) is incorrectly interpreting the robustness principle as saying there is no need for clear rules on protocol evolvability/extensions. For example, section 6, "relying on implementations to consistently apply the robustness principle is not a good strategy for extensibility".

Yes, thank you for saying that, I hadn't seen it so clearly. I do regret that we failed to discuss the robustness principle explicitly in RFC6709. However, it's in the background of https://tools.ietf.org/html/rfc6709#section-4.7 .

> In the routing area, we do have rules and we use the principle to ensure interoperability, as we don't have the luxury to do a "forklift". Section 8's "it is not always possible to produce a design that allow all current protocol participants to continue to participate", my question would be "but does it harm the network"?
> 
> Actually most of the document confusingly is not contradicting Postel's principle but supporting it (except for the nuances which seem to condone forklifts). It just erroneously blames Postel for sloppy implementations. For the document to summarize saying "the robustness principle can, and should, be avoided" as it is harmful (I think) will be harmful to the Internet.

I agree. I think that as a warning against blind reliance on the principle, the document is correct and useful. But IMHO that doesn't justify the title, or the recommendation in the Abstract.

To be constructive, I suggest:

Title: The Unintended Consequences of the Robustness Principle

Abstract (last sentence): For a protocol that is actively maintained, the robustness principle can often be avoided.

If there was a Conclusions section, I expect I'd have a suggested change for that too.

> Hopefully more folks will read it-
> (probably discussion is more appropriate on the architecture-discuss list)

Yes, but that list is generally very quiet, unfortunately.

   Brian

> Deborah
> 
> -----Original Message-----
> From: IAB <iab-bounces@iab.org> On Behalf Of internet-drafts@ietf.org
> Sent: Monday, May 06, 2019 10:40 PM
> To: i-d-announce@ietf.org
> Cc: iab@iab.org
> Subject: [IAB] I-D Action: draft-iab-protocol-maintenance-03.txt
> 
> 
> A New Internet-Draft is available from the on-line Internet-Drafts directories.
> This draft is a work item of the Internet Architecture Board IETF of the IETF.
> 
>         Title           : The Harmful Consequences of the Robustness Principle
>         Author          : Martin Thomson
> 	Filename        : draft-iab-protocol-maintenance-03.txt
> 	Pages           : 11
> 	Date            : 2019-05-06
> 
> Abstract:
>    Jon Postel's famous statement of "Be liberal in what you accept, and
>    conservative in what you send" is a principle that has long guided
>    the design and implementation of Internet protocols.  The posture
>    this statement advocates promotes interoperability in the short term,
>    but can negatively affect the protocol ecosystem over time.  For a
>    protocol that is actively maintained, the robustness principle can,
>    and should, be avoided.
> 
> 
> The IETF datatracker status page for this draft is:
> https://urldefense.proofpoint.com/v2/url?u=https-3A__datatracker.ietf.org_doc_draft-2Diab-2Dprotocol-2Dmaintenance_&d=DwICaQ&c=LFYZ-o9_HUMeMTSQicvjIg&r=6UhGpW9lwi9dM7jYlxXD8w&m=VZUxXboWY44rtZcmcswiLQuQ8TmW6g7F7Azgl-j0amw&s=Fxp9wRoCVRJ_8BZBzY1MoExjRlVCegLbFtq8txcr6F8&e=
> 
> There are also htmlized versions available at:
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> A diff from the previous version is available at:
> https://urldefense.proofpoint.com/v2/url?u=https-3A__www.ietf.org_rfcdiff-3Furl2-3Ddraft-2Diab-2Dprotocol-2Dmaintenance-2D03&d=DwICaQ&c=LFYZ-o9_HUMeMTSQicvjIg&r=6UhGpW9lwi9dM7jYlxXD8w&m=VZUxXboWY44rtZcmcswiLQuQ8TmW6g7F7Azgl-j0amw&s=JdV3Cux54CLr3GLrhc4SapVMu0mBchg-65xKrwqYPCo&e=
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