Re: Robert Wilton's Discuss on draft-ietf-bfd-unsolicited-11: (with DISCUSS and COMMENT)

[Reshad Rahman <[e-mail]>]

 Rob, thanks for catching this, the container has been removed fairly recently, I'll update section 4.1.
Regards,Reshad.
    On Thursday, April 27, 2023, 12:06:15 PM EDT, Rob Wilton (rwilton) <rwilton=[e-mail]> wrote:  
 
 
Hi Reshad,
 
  
 
I think that looks good to me.
 
  
 
Whilst checking, I noticed this comment at the beginning of section 4.1:
 
  
 
   For operational data, a new "unsolicited" container has been added
 
   for BFD IP single-hop sessions.
 
  
 
Please can you check whether that is still accurate, but otherwise the changes look good to me, and I’ve already cleared my discuss previously.
 
  
 
Regards,
 
Rob
 
  
 
  
 
  
 
From: Reshad Rahman <reshad=[e-mail]>
Sent: 27 April 2023 16:37
To: The IESG <[e-mail]>; Rob Wilton (rwilton) <[e-mail]>
Cc: [e-mail]; [e-mail]; [e-mail]
Subject: Re: Robert Wilton's Discuss on draft-ietf-bfd-unsolicited-11: (with DISCUSS and COMMENT)
 
  
 
Hi Rob,
 
  
 
Changes made in rev-15 to simplify the model:
 
- Removed the feature for global config, also removed the global enabled leaf
 
- At the per-interface level, the enabled leaf doesn't depend on the params-per-interface feature anymore
 
- Removed the must statements (since global parms config is not feature dependent anymore)
 
  
 
Other changes:
 
- Changed role from enum to identity (Jeff's suggestion)
 
- Updated acknowledgement section
 
  
 
Regards,
 
Reshad.
 
  
 
  
 
  
 
Name:        draft-ietf-bfd-unsolicited
 
Revision:    15
 
Title:        Unsolicited BFD for Sessionless Applications
 
Document date:    2023-04-27
 
Group:        bfd
 
Pages:        18
 
URL:            https://www.ietf.org/archive/id/draft-ietf-bfd-unsolicited-15.txt
 
Status:         https://datatracker.ietf.org/doc/draft-ietf-bfd-unsolicited/
 
Htmlized:       https://datatracker.ietf.org/doc/html/draft-ietf-bfd-unsolicited
 
Diff:           https://author-tools.ietf.org/iddiff?url2=draft-ietf-bfd-unsolicited-15
 
  
 
  
 
On Wednesday, April 19, 2023, 09:31:32 AM EDT, Rob Wilton (rwilton) <rwilton=[e-mail]> wrote:
 
  
 
  
 
Hi Reshad,
 
 
 
Please see inline …
 
 
 
From: Reshad Rahman <[e-mail]>
Sent: 19 April 2023 03:38
To: The IESG <[e-mail]>; Rob Wilton (rwilton) <[e-mail]>
Cc: [e-mail];[e-mail]; [e-mail]; Jeffrey Haas <[e-mail]>
Subject: Re: Robert Wilton's Discuss on draft-ietf-bfd-unsolicited-11: (with DISCUSS and COMMENT)
 
 
 
Hi Rob,
 
 
 
Thanks for the feedback. And no need to apologize since it took us much longer to respond to your initial comments...
 
 
 
Please see inline.
 
 
 
On Tuesday, April 18, 2023, 11:55:03 AM EDT, Rob Wilton (rwilton) <[e-mail]> wrote: 
 
 
 
 
 
Hi Reshad,
 
 
 
Apologies for the delay.
 
 
 
The changes that you have made are sufficient to clear my discuss.
 
 
 
As a non-discuss (and non-blocking) comment, I do still find this hierarchical configuration to be somewhat complex on two points:
 
 
 
1.    The configuration is under optional feature statements both at the global level and the per-interface level, and I think that the model would allow neither feature to be specified, in which case the defaults would be ambiguous.  I’m sure that the WG has a good reason for why it is designed the way it is, but I can’t help wondering whether it would make the model cleaner/simpler to require support for the global level configuration, and only have per-interface level configuration under an optional feature.  I.e., if this was done, then logically, there are always well-defined default values without requiring evaluation of the must-statement.
 
<RR> Initially when I did the 2 features I was looking for a way to enforce that at least 1 of the 2 features is supported but afaik there's no way in YANG 1.1 to do that. When I addressed your comments about config hierarchy/inheritance, I added the must statements to address that. I did consider removing one of the features but it wasn't clear to me which one should be removed, in that some implementations might prefer having just global config and others would prefer per-interface configuration. But I'm ok with making the global config mandatory (i.e. remove the feature) if there's consensus on that, need to discuss with the co-authors too.
 
[Rob Wilton (rwilton)]
 
Ack.  The only reason that I went with making supporting global configuration mandatory was that it felt like it should be simpler to implement, and that it makes the inheritance more robust/simpler.
 
 
 
I think that it maybe possible to achieve what you desire in YANG 1.1 (i.e., require at least 1 of the 2 features to always be enabled), but I don’t think that it is a good idea, and hence I wouldn’t recommend that you do it.  Unless I’m mistaken, what you desire may be achieved in YANG by defining a third feature (let’s call it HACK) that has its own if-feature sub-statement of “(GLOBAL or PER-INTERFACE)”, and then make everything at the top level of the module conditional on the “HACK” feature.  However, I think that this would probably just make the model ugly and confusing to users and probably isn’t worth the additional complexity/confusion that it would likely cause.
 
 
 
Regards,
Rob
 
 
 
1.    I don’t think that the descriptions are necessarily clear about if, and how, single-interval on the interface is allowed to override desired-min-tx-interval and required-min-rx-interval configured globally, or vice-versa.  Please consider whether it would be helpful to update the descriptions of these fields under the interface configuration to clarify these semantics.
 
 <RR> Ack, I will update the description.
 
 
 
Regards,
 
Reshad.
 
 
 
Regards,
 
Rob
 
 
 
 
 
From: Reshad Rahman <[e-mail]>
Sent: 21 March 2023 01:32
To: The IESG <[e-mail]>; Rob Wilton (rwilton) <[e-mail]>
Cc: [e-mail];[e-mail];[e-mail]; Jeffrey Haas <[e-mail]>
Subject: Re: Robert Wilton's Discuss on draft-ietf-bfd-unsolicited-11: (with DISCUSS and COMMENT)
 
 
 
Hi Rob,
 
 
 
I believe rev-12 addresses the 3 DISCUSS points below.
 
 
 
We still have to do further updates to the document.
 
 
 
Regards,
 
Reshad.
 
 
 
On Monday, December 12, 2022, 12:03:19 PM EST, Robert Wilton via Datatracker <[e-mail]> wrote: 
 
 
 
 
 
Robert Wilton has entered the following ballot position for
 
draft-ietf-bfd-unsolicited-11: Discuss
 
 
 
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The document, along with other ballot positions, can be found here:
 
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----------------------------------------------------------------------
 
DISCUSS:
 
----------------------------------------------------------------------
 
 
 
Hi,
 
 
 
Thanks for this document.
 
 
 
Please see my comments below for more details, but I'm balloting discuss on 3
 
points: (1) The document is somewhat unclear as to whether the configuration is
 
applied hierarchically (I presume that it is, if not then my second discuss
 
point is not valid and can be ignored). (2) As specified, I don't think that
 
the hierarchical configuration will work, because the interface level leaf
 
"defaults" will override an explicit value configured globally.  I.e.,
 
logically, the interface level leaf, if in scope, will always have a value. (3)
 
The document should provide an instance-data example in the appendix to
 
illustrate the use of this configuration.
 
 
 
Regards,
 
Rob
 
 
 <snip>