Re: [IPFIX] [Technical Errata Reported] RFC7012 (3852)

Brian

Firstly going back to my original problem, I think that would be
better addressed by

OLD

Definitions of timestamp data types have been clarified.

NEW

Definitions of timestamp data types have been clarified and
the definition of the epochs has been moved to sections
6.1.7 through 6.1.11 of RFC 7011

End

Your new text is also helpful.

Then there is the problem of the IANA registry pointing to
an obsolete RFC, which then takes you to RFC7012 which
does not define the IEs.

Consider IE 150, the reader is directed to RFC7012 by the
registry header, and finds the datatype isdateTimeSeconds
(which they dutifully look up in RFC7012 as indicated
in the registry) they find the definition of dateTimeSeconds
without the epoch and then what... For the definition
of the IE to be complete, the reader needs the epoch
which arguably now belongs in the registry, but is missing.
I think that the root cause is that when we made the
registry the definitive definition of the IEs, we
did not add sufficient information in the case of the
time definitions.

Now we have one other issue which I have been puzzling
over since you sent the email and can't quite get my
head around. You use the term "value" in the ADT
context. With for example i.e. 52 (min TTL) it's
easy to imagine what "value" means however you
represent it. However I am struggling to understand
whether it is meaningful to define the "value" of IE
150:"The absolute timestamp of the first packet of
this Flow" is without some specific epoch. This
issue is addressed in I.E. 1 by specifying the count
relative to a previous instance of count, so I think
whilst that is a value, the timestamps are not.

We may need a call to work though this and another issue
I am about to raise on the IPFIX list.

- Stewart

On 31/12/2013 12:44, Brian Trammell wrote:
> hi Stewart,
>
> Stewart Bryant (stbryant) wrote:
>> Certainly something is needed. I was thinking of using IPFIX as an information gathering method in a radio context, and went to look at the definition of the types and could not find the epoch, or even a reference to the epoch. Now part of the problem (which was my fault) was that I did not notice at the time that the elements were defined by the obsolete RFC5102 and went straight to the new RFC. However having the definitions in an obsolete RFC also seems problematic, since it puts the IEs in a strange state. Since RFC 7012 replaces RFC5102 and includes the definitions you would expect the definition in RFC7012 to replace the definition in RFC5102, but those definitions are, as I explained incomplete.
> This is intentional. See below.
>
>> I need to look at this some more when I get back to work, but I am now also concerned that if the epoch can change, the definition of the existing IEs is now unreliable.
> The definition of the existing IEs is based upon the definition of the
> ADT itself in 7012 as well as the definition of the ADT representation
> within the IPFIX protocol in 7011. It is not the intention that reading
> 7012 tells you how to encode IEs for use with IPFIX; that's what section
> 6.1 of 7011 is for.
>
>> You will notice in the errata that I did suggest that an alternative resolution would be to include a reference to the epoch text.
> The point is that the ADT _explicitly_ does not have a binding to an
> epoch, as epochs are only necessary when using integral representations
> of timestamps. IPFIX's representations for these ADTs are integral, but
> bindings to other representations need not be (see, for example,
> draft-trammell-ipfix-text-adt, which recommends ISO8601-style timestamps
> for textual representations of IE values).
>
> I'd suggest instead somehow expanding the present text in 7012 to
> reiterate that if you're using IPFIX, the representations of the ADTs
> are in 7011:
>
> OLD para 2 sec 3.1 7012:
>
>     The current encodings of these data types for use with the IPFIX
>     protocol are defined in [RFC7011]; encodings allowing the use of the
>     IPFIX Information Elements [IANA-IPFIX] with other protocols may be
>     defined in the future by referencing this document.
>
> NEW para 2 sec 3.1 7012:
>
>     The abstract data type definitions in this section are intended
>     only to define the values which can be taken by Information
>     Elements of each type. The encodings of these data types for
>     use with the IPFIX protocol are defined in Section 6.1 of
>     [RFC7011]; encodings  allowing the use of the IPFIX Information
>     Elements [IANA-IPFIX] with other protocols may be defined in the
>     future by referencing this document.
>
> Best regards,
>
> Brian
>
>
>> Stewart
>>
>>
>>
>> Sent from my iPad
>>
>>> On 31 Dec 2013, at 08:50, "Brian Trammell" <[email protected]> wrote:
>>>
>>> hi Paul, all,
>>>
>>> +n.
>>>
>>> The separation between ADTs and ADT encoding between 7012 and 7011 was explicit and purposeful. Specifically, we do _not_ want to exclude other representations of the IPFIX Information Model from being based upon other encodings of these ADTs, whether ISO 8601 (which either has no epoch or epoch 0000-00-00 00:00 UTC, depending on how you count), NTP (1904), Julian day based counting, etc, etc, etc…
>>>
>>> If there is confusion on this point, I’d suggest adding more explanatory text on this point to Paragraph 2 of the front matter to section 3.1. But as is, I emphatically recommend rejection of this reported erratum.
>>>
>>> Best regards,
>>>
>>> Brian
>>>
>>>> On 31 Dec 2013, at 03:58, Paul Aitken <[email protected]> wrote:
>>>>
>>>> +1
>>>>
>>>> If anyone was going to raise an errata on this, it would have been me ;-)
>>>>
>>>> I've pointed this issue out before, probably more than once - and have been encouraged to read RFC 3444.
>>>>
>>>> P.
>>>>
>>>>
>>>>> On 30/12/2013 09:23, Andrew Feren wrote:
>>>>> The encoding for the time data types is specified RFC 7011 Sections
>>>>> 6.1.7 through 6.1.10.
>>>>>
>>>>> -Andrew
>>>>>
>>>>>> On 12/30/2013 10:13 AM, RFC Errata System wrote:
>>>>>> The following errata report has been submitted for RFC7012,
>>>>>> "Information Model for IP Flow Information Export (IPFIX)".
>>>>>>
>>>>>> --------------------------------------
>>>>>> You may review the report below and at:
>>>>>> http://www.rfc-editor.org/errata_search.php?rfc=7012&eid=3852
>>>>>>
>>>>>> --------------------------------------
>>>>>> Type: Technical
>>>>>> Reported by: Stewart Bryant <[email protected]>
>>>>>>
>>>>>> Section: 3.1.15-17
>>>>>>
>>>>>> Original Text
>>>>>> -------------
>>>>>> 3.1.15. dateTimeSeconds
>>>>>>
>>>>>>    The type "dateTimeSeconds" represents a time value expressed with
>>>>>>    second-level precision.
>>>>>>
>>>>>> 3.1.16. dateTimeMilliseconds
>>>>>>
>>>>>>    The type "dateTimeMilliseconds" represents a time value expressed
>>>>>>    with millisecond-level precision.
>>>>>>
>>>>>> 3.1.17. dateTimeMicroseconds
>>>>>>
>>>>>>    The type "dateTimeMicroseconds" represents a time value expressed
>>>>>>    with microsecond-level precision.
>>>>>>
>>>>>> 3.1.18. dateTimeNanoseconds
>>>>>>
>>>>>>    The type "dateTimeNanoseconds" represents a time value expressed with
>>>>>>    nanosecond-level precision.
>>>>>>
>>>>>>
>>>>>> Corrected Text
>>>>>> --------------
>>>>>> 3.1.15. dateTimeSeconds
>>>>>>
>>>>>>    The type "dateTimeSeconds" represents a time value in units of
>>>>>>    seconds based on coordinated universal time (UTC).  The choice of an
>>>>>>    epoch, for example, 00:00 UTC, January 1, 1970, is left to
>>>>>>    corresponding encoding specifications for this type, for example, the
>>>>>>    IPFIX protocol specification.  Leap seconds are excluded.  Note that
>>>>>>    transformation of values might be required between different
>>>>>>    encodings if different epoch values are used.
>>>>>>
>>>>>> 3.1.16. dateTimeMilliseconds
>>>>>>
>>>>>>    The type "dateTimeMilliseconds" represents a time value in units of
>>>>>>    milliseconds based on coordinated universal time (UTC).  The choice
>>>>>>    of an epoch, for example, 00:00 UTC, January 1, 1970, is left to
>>>>>>    corresponding encoding specifications for this type, for example, the
>>>>>>    IPFIX protocol specification.  Leap seconds are excluded.  Note that
>>>>>>    transformation of values might be required between different
>>>>>>    encodings if different epoch values are used.
>>>>>>
>>>>>> 3.1.17. dateTimeMicroseconds
>>>>>>
>>>>>>    The type "dateTimeMicroseconds" represents a time value in units of
>>>>>>    microseconds based on coordinated universal time (UTC).  The choice
>>>>>>    of an epoch, for example, 00:00 UTC, January 1, 1970, is left to
>>>>>>    corresponding encoding specifications for this type, for example, the
>>>>>>    IPFIX protocol specification.  Leap seconds are excluded.  Note that
>>>>>>    transformation of values might be required between different
>>>>>>    encodings if different epoch values are used.
>>>>>>
>>>>>> 3.1.18. dateTimeNanoseconds
>>>>>>
>>>>>>    The type "dateTimeNanoseconds" represents a time value in units of
>>>>>>    nanoseconds based on coordinated universal time (UTC).  The choice of
>>>>>>    an epoch, for example, 00:00 UTC, January 1, 1970, is left to
>>>>>>    corresponding encoding specifications for this type, for example, the
>>>>>>    IPFIX protocol specification.  Leap seconds are excluded.  Note that
>>>>>>    transformation of values might be required between different
>>>>>>    encodings if different epoch values are used.
>>>>>>
>>>>>>
>>>>>> Notes
>>>>>> -----
>>>>>> Although section 1.1 says : - "Definitions of timestamp data types have been clarified." The edited text has removed the epoch definition, and this does not seem to have been incorporated elsewhere in the RFC.
>>>>>>
>>>>>> Without a specified epoch, there is no unique definition of the timestamps.
>>>>>>
>>>>>> My proposal above is to revert to the RFC5102 definitions. RFC7102 is intended to be backwards compatible with RFC5102 and thus the definitions need to be technically identical. Alternatively, if the text is now included elsewhere in RFC7012 or in another RFC, it would be helpful to the reader to provide a reference to the epoch definition in an editorial update to dateTimeX definitions in RFC7102.
>>>>>>
>>>>>> Instructions:
>>>>>> -------------
>>>>>> This errata 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 (IESG)
>>>>>> can log in to change the status and edit the report, if necessary.
>>>>>>
>>>>>> --------------------------------------
>>>>>> RFC7012 (draft-ietf-ipfix-information-model-rfc5102bis-10)
>>>>>> --------------------------------------
>>>>>> Title               : Information Model for IP Flow Information Export (IPFIX)
>>>>>> Publication Date    : September 2013
>>>>>> Author(s)           : B. Claise, Ed., B. Trammell, Ed.
>>>>>> Category            : PROPOSED STANDARD
>>>>>> Source              : IP Flow Information Export
>>>>>> Area                : Operations and Management
>>>>>> Stream              : IETF
>>>>>> Verifying Party     : IESG
>>>>>> _______________________________________________
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>>>>>> https://www.ietf.org/mailman/listinfo/ipfix
>>>>> _______________________________________________
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