Let me see if I can refine a sentence or two, since the whole kerfuffle is 
largely my fault anyhow (and I managed to reverse my position in public within 
about 48 hours).  If someone wants to run with those I’d be honored…

—Dave

> On Feb 17, 2023, at 8:08 AM, John Scudder <[email protected]> wrote:
> 
> Hm, OK. So this is now sounding more like a “hold for document update” 
> erratum which is our vehicle for saying “the spec could have been clearer, 
> here is some improved text, maybe use this if you do a bis”.
> 
> I can verify it as HFDU with an updated description — if we have some 
> agreed-upon text.
> 
> —John
> 
>> On Feb 13, 2023, at 4:52 PM, Dave Katz <[email protected]> wrote:
>> 
>> The intent of the diag field is to leave a breadcrumb behind about what 
>> caused the last session failure, so that humans and/or fault analysis can 
>> try to guess what happened.  If the session comes back quickly, overwriting 
>> the diag on the transition to UP will wipe out that information.
>> 
>> So I actually am changing my mind on this and would oppose the change.  The 
>> erratum, to the extent that it exists is actually in the description of the 
>> field, which should say (in effect) “the reason for the most recent change 
>> in the local session state except for going Up because we know why we did 
>> that”, or something.  But the normative text is sprinkled throughout where 
>> the spec calls out when to set the local diag value (which is always copied 
>> to the protocol packet) and that does not need to change.
>> 
>> Thanks for making me think twice, er three times, or something.
>> 
>> —Dave
>> 
>>> On Feb 13, 2023, at 6:06 AM, John Scudder <[email protected]> wrote:
>>> 
>>> I guess it hinges on whether the reinitialization happens when you 
>>> transition out of Down, or into Up. As the erratum is written now it’s when 
>>> you transition into Up, which appears to make sense, and applies whether 
>>> the transition is from Down or from Init. But I’ll wait a little longer for 
>>> any further discussion before verifying the erratum. 
>>> 
>>> —John
>>> 
>>>> On Feb 13, 2023, at 4:37 AM, Gļebs Ivanovskis 
>>>> <[email protected]> wrote:
>>>> 
>>>> 
>>>> Hi!
>>>> 
>>>> Wouldn't it make sense to re-initialize bfd.LocalDiag when transitioning 
>>>> to Init state as well?
>>>> 
>>>> Section 6.8.6 describes a case when bfd.SessionState goes from Down to 
>>>> Init:
>>>> 
>>>>         If bfd.SessionState is Down
>>>>             If received State is Down
>>>>                 Set bfd.SessionState to Init
>>>> 
>>>> Best regards,
>>>> Glebs
>>>> 
>>>> 
>>>> On 08.02.23 19:58, John Scudder wrote:
>>>>> Hi Everyone,
>>>>> 
>>>>> I plan to verify this in the near future (let’s say, Monday Feb 13) 
>>>>> unless anyone objects. 
>>>>> 
>>>>> Thanks,
>>>>> 
>>>>> —John
>>>>> 
>>>>> 
>>>>>> On Nov 6, 2022, at 4:27 AM, RFC Errata System <[email protected]>
>>>>>> wrote:
>>>>>> 
>>>>>> The following errata report has been submitted for RFC5880,
>>>>>> "Bidirectional Forwarding Detection (BFD)".
>>>>>> 
>>>>>> --------------------------------------
>>>>>> You may review the report below and at:
>>>>>> 
>>>>>> https://urldefense.com/v3/__https://www.rfc-editor.org/errata/eid7240__;!!NEt6yMaO-gk!DSW_aH2n7cYViXw08rr41mmdkcad5rzUky6aMWE1XW-uhZqqdIELlYuLQ20Sw8Z1cTiyiqHvd7VyqUJIsm_Lmg$
>>>>>> 
>>>>>> 
>>>>>> --------------------------------------
>>>>>> Type: Technical
>>>>>> Reported by: Jeffrey Haas 
>>>>>> <[email protected]>
>>>>>> 
>>>>>> 
>>>>>> Section: 6.8.1
>>>>>> 
>>>>>> Original Text
>>>>>> -------------
>>>>>> bfd.LocalDiag
>>>>>> 
>>>>>>    The diagnostic code specifying the reason for the most recent
>>>>>>    change in the local session state.  This MUST be initialized to
>>>>>>    zero (No Diagnostic).
>>>>>> 
>>>>>> Corrected Text
>>>>>> --------------
>>>>>> [Proposed text]
>>>>>> 
>>>>>> bfd.LocalDiag
>>>>>> 
>>>>>>    The diagnostic code specifying the reason for the most recent
>>>>>>    change in the local session state.  This MUST be initialized to
>>>>>>    zero (No Diagnostic).  It MUST also be re-initialized to zero
>>>>>>    (No Diagnostic) when the local session state transitions to Up.
>>>>>> 
>>>>>> Notes
>>>>>> -----
>>>>>> RFC 5880 at various points calls out setting the value of bfd.LocalDiag 
>>>>>> as part of state transitions.  The text defining the feature calls for 
>>>>>> it to be initialized to zero.  However, it doesn't define under what 
>>>>>> conditions it should be re-initialized to zero.
>>>>>> 
>>>>>> One possible place where it may be reinitialized is when the session 
>>>>>> transitions back to Up, indicating that prior issues may have been 
>>>>>> cleared.
>>>>>> 
>>>>>> Instructions:
>>>>>> -------------
>>>>>> This erratum is currently posted as "Reported". If necessary, please
>>>>>> use "Reply All" to discuss whether it should be verified or
>>>>>> rejected. When a decision is reached, the verifying party
>>>>>> can log in to change the status and edit the report, if necessary.
>>>>>> 
>>>>>> --------------------------------------
>>>>>> RFC5880 (draft-ietf-bfd-base-11)
>>>>>> --------------------------------------
>>>>>> Title               : Bidirectional Forwarding Detection (BFD)
>>>>>> Publication Date    : June 2010
>>>>>> Author(s)           : D. Katz, D. Ward
>>>>>> Category            : PROPOSED STANDARD
>>>>>> Source              : Bidirectional Forwarding Detection
>>>>>> Area                : Routing
>>>>>> Stream              : IETF
>>>>>> Verifying Party     : IESG
>>>>>> 
>>> 
>> 
> 

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