Re: [Last-Call] Yangdoctors last call review of draft-ietf-bfd-rfc9127-bis-01

[tom petch <[e-mail]>]

On 03/02/2022 17:28, Mahesh Jethanandani wrote:
> Hi Jan,
>
> Thanks first of all for the review.
>
>> On Feb 3, 2022, at 3:22 AM, Jan Lindblad via Datatracker <[e-mail]> wrote:
>>
>> Reviewer: Jan Lindblad
>> Review result: Ready with Issues
>>
>> This is the last call YANG Doctor review of draft-ietf-bfd-rfc9127-bis.
>> Browsing the mail archives, this has been a long story. Realizing that the
>> context of the bis is to fix a particular issue, I have focused only on the
>> diffs from RFC 9127. I feel any additional nitpicks I might find in a complete
>> review would not be welcome at this stage.
>>
>> I have reviewed the diffs, and find them fulfill the desired technical goals.
>> Since this update breaks backwards compatibility as defined in RFC 6020 sec 10
>> and RFC 7950 sec 11, the process for approving this change has been discussed
>> at length. One argument that has been put forward for going ahead is that the
>> previous version of this module was released only a short time ago, so there is
>> no proliferation of impacted systems in the field.
>>
>> Another argument has been that the YANG Versioning Design Team is working on
>> updated backwards compatibility rules. The Ver-DT proposed updates to the
>> compatibility rules would indeed allow a change of this kind under certain
>> conditions. A key condition for allowing such a break with the backwards
>> compatibility is that the module revision history announces this break clearly
>> to all readers. This is not the case in the -01 version of the modules.
>>
>>    revision 2022-01-04 {
>>        description
>>          "Updates to add client configuration parameters feature.";
>>
>> In my YANG Doctor opinion, updating the revision statement to clearly state
>> that this version is not backwards compatible with the previous version is an
>> absolute requirement. I think it would also be fair to module readers to add a
>> few sentences explaining what's going on here.
>
> How does this sound?
>
> OLD:
>        "Updates to add client configuration parameters feature.";
>
> NEW:
>        "Updates to add client configuration parameters feature.
>         This update breaks backward compatability with earlier
>         version of the model. The new feature prevents up to
>         three client configuration parameters from being
>         included, where they were not needed.";


I think that you need more than that (for the reader who does not follow 
the BFD WG).  I think that there needs to be a reference to where the 
compatability rules are - RFC7950 s.11 - and the nature of the breakage 
in the language of NETMOD so that readers can judge the impact thereof.

Tom Petch

>
> Thanks.
>
>
> Mahesh Jethanandani
> [e-mail]
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