Re: [netmod] YANG Versioning: discussion around 7950 bis or errata (from Key Issue #1)

[Rodney Cummings <[e-mail]>]

> It is easy to write a short RFC updating RFC 7950, changing one sentence from MUST to SHOULD.

I agree. I found that I cannot enter a response to the poll, because I disagree with both Option 1 and Option 2.

My concern is that there are many people out there who are implementing YANG, but who do not follow discussions on this mailing list. I'm concerned that there is a serious risk that those people will interpret the change from MUST to SHOULD as "backward compatibility is irrelevant for YANG". We all know that the concern is about bug fixes and so on, but without explaining that in a short and focused manner (i.e., the short RFC described above), that will be lost in the noise of the larger draft-ietf-netmod-yang-module-versioning change.

draft-ietf-netmod-yang-module-versioning is a great draft, but I think it should move forward as an independent RFC, distinct from the MUST/SHOULD change.

Rodney Cummings

-----Original Message-----
From: netmod <[e-mail]> On Behalf Of Jürgen Schönwälder
Sent: Tuesday, September 26, 2023 5:24 PM
To: Jason Sterne (Nokia) <[e-mail]>
Cc: [e-mail]
Subject: Re: [netmod] YANG Versioning: discussion around 7950 bis or errata (from Key Issue #1)

It is easy to write a short RFC updating RFC 7950, changing one sentence from MUST to SHOULD. This is inline with the goal to not change the language, i.e., to keep the version numbers.

/js

On Tue, Sep 26, 2023 at 03:00:19PM +0000, Jason Sterne (Nokia) wrote:
> Hello NETMOD WG,
>
> We've had a poll going for a few weeks to determine if we require YANG 1.2 for allowing ("SHOULD NOT") NBC changes (see "Poll on YANG Versioning NBC Approach").
>
> As part of that, some discussion has happened on the list around
> potentially doing an errata for RFC7950/6020 or a bis of 7950/6020 (if
> rough consensus is reached for option 1 of the poll)
>
> 7-8 of us discussed this in the YANG Versioning weekly call group today.
>
> First of all: this question of mechanics (errata vs bis vs Module Versioning draft) is orthogonal to the poll. Let's first and separately resolve the poll and confirm if we need YANG 1.2 or not (that's the fundamental question the poll is resolving - everything else is a subsequent issue to be discussed). We'll let the chairs confirm when/if rough consensus on the poll has been reached.
>
> But *if* the answer to the poll is option 1, then the weekly call group was unanimous that we should not do an errata for RFC7950/6020 and we should not do a 7950/6020 bis. We should just continue with the Module Versioning draft which will update 7950 and 6020.
>
> The primary reason is that we shouldn't just change MUST NOT to SHOULD NOT without also tying it together with the mandatory top level rev:non-backwards-compatible extension when an NBC change is done. Changing the NBC rule to SHOULD NOT needs to be in the same RFC as the mandatory rev:non-backwards-compatible tag.
>
> Other reasons:
>
>   *   an errata probably isn't correct since this isn't fixing an intent that was present back when 7950 was written (it was clearly the intent at the time to block NBC changes)
>   *   a bis would be odd without actually introducing other changes to YANG and changing the version (this discussion is all based on "if the answer to the poll is option 1")
>
> Jason (he/him)
>

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--
Jürgen Schönwälder              Constructor University Bremen gGmbH
Phone: [phone]         Campus Ring 1 | 28759 Bremen | Germany
Fax:   [phone]         <https://constructor.university/>

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