Re: [sfc] New Version Notification for draft-ietf-sfc-multi-layer-oam-03.txt

["Joel M. Halpern" <[e-mail]>]

Not comment on your other questions, and hoping that Greg will engage 
you in discussion on them, I want to comment on the "implementation 
section" comment.

There are two aspects to this question.
The first aspect is that you have (and the WG as a whole can) ask "are 
there implementations?"  I think we all expect authors to answer that 
question when asked.  The answer will likely end up in the shepherd 
writeup for the information of the IESG.

Separately, given that it appears that there is not an available 
implementation at this time, it is not the normal practice to expect 
that an implementation section be put in a draft highlighting that gap. 
That is not the expected practice as I understand it for the IETF as a 
whole, nor is it a practice that the SFC working group has adopted. 
There is a large difference between making sure that the group is aware 
of the status and explicitly stating the gap in the I-D.

It is certainly worth while to note, as you do, that there are 
implementations of some of the other OAM proposals.  I believe (although 
I do not have the evidence to hand) that those implementations have 
proven useful in practice, which is important information for the WG. 
If you have more details on that, I think taht would be good information 
(I am not asking for an OAM implementations I-D.  Just some email comments.)

Yours,
Joel

On 5/10/19 11:34 PM, Carlos Pignataro (cpignata) wrote:
> Dear SFC Chairs,
> 
> I believe Greg’s response is mis-representing my position, and 
> mis-quoting what I wrote, as follows:
> 
> Greg wrote:
>> Thus I'm puzzled why are you demanding that this optional section be 
>> added to the draft now?
> 
> 1. I am not demanding. Instead I wrote:
>>
>>     Request: Can we please add an “Implementation Status” section?
>>
> 
> Greg wrote:
>> Thus I'm puzzled why are you demanding that this optional section be 
>> added to the draft now?
> 
> However, I suggested this over a year ago, and then 6 months ago, as per 
> the list posting included below. Not “now”.
>>
>>     * March 29, 2018, on draft-wang-sfc-multi-layer-oam
>>     https://mailarchive.ietf.org/arch/msg/nvo3/eNRV-7GLWO_lLeeXwI97HhTrtBo
>>     * October 27, 2018, on adoption
>>     https://mailarchive.ietf.org/arch/msg/sfc/wuK4MiyeOMNbXrRIYjiW7zCtZ70
>>
> 
> 
> My main request is that on-list comments and suggestions are responded 
> to and discussed on technical merits. The previous two/three times, my 
> comment was ignored and not responded to.
> 
> I also do not understand why questions are selectively ignored. I asked 
> three questions on this email, but received a response to only one.
> 
> 
> Dear Greg,
> 
> Sorry to have puzzled you. That was not the intention. The intention was 
> to engage in a technical discussion about an Internet Best Current Practice.
> 
> Apologies if I sounded (or was) repetitive, just seeking an answer.
> 
> I understand the “Implementation Status” section is optional, but since 
> Internet documents are (among other things) for interoperability, I 
> kindly request you consider adding that optional section. Besides the 
> one-liner you quoted, RFC 7942 goes into great lengths at explaining the 
> importance of doing so.
> 
> You also mention:
>> Yes, the work on the implementation is ongoing
> 
> Does this mean “the implementation” as in only one?
> 
> Best,
> 
> — Carlos Pignataro
> 
> 
>> On May 10, 2019, at 11:14 PM, Greg Mirsky <[e-mail] 
>> <mailto:[e-mail]>> wrote:
>>
>> Hi Carlos,
>> I'm sure you've read the section "Implementation Status" in RFC 7942 
>> that opens with the following sentence:
>>    Each Internet-Draft may contain a section entitled "Implementation 
>> Status".
>> Thus I'm puzzled why are you demanding that this optional section be 
>> added to the draft now? Yes, the work on the implementation is ongoing 
>> and when there will be updates, we'll certainly share them with the WG.
>>
>> Regards,
>> Greg
>>
>> On Fri, May 10, 2019 at 7:53 PM Carlos Pignataro (cpignata) 
>> <[e-mail] <mailto:[e-mail]>> wrote:
>>
>>     Hi, Greg, SFC,
>>
>>     In order to understand the positioning of
>>     draft-ietf-sfc-multi-layer-oam, please find 3 high-level yet very
>>     important questions and associated comments for consideration.
>>
>>     To avoid potential misinterpretation and to be explicit on this
>>     note's intention: this email does not imply interest in this
>>     draft, does not mean support, I have not read the document fully.
>>
>>     But a quick note for completeness:
>>
>>     1. “Implementation Status” Section.
>>
>>     The authors seem to selectively respond to comments.
>>
>>     I asked for an “Implementation Status” Section [RFC7942] at least
>>     two or three times:
>>     * March 29, 2018, on draft-wang-sfc-multi-layer-oam
>>     https://mailarchive.ietf.org/arch/msg/nvo3/eNRV-7GLWO_lLeeXwI97HhTrtBo
>>     * October 27, 2018, on adoption
>>     https://mailarchive.ietf.org/arch/msg/sfc/wuK4MiyeOMNbXrRIYjiW7zCtZ70
>>
>>     Instead, this drafts seems to be inventing a full blown protocol
>>     without implementation practice.
>>
>>     SFC Chairs, could we please follow-up on repeated comments made on
>>     the list and track a disposition? These are over a year old, and
>>     part of an adoption call.
>>
>>     Request: Can we please add an “Implementation Status” section?
>>
>>
>>     2. New protocol invention outside of / rogue to an SFC OAM Framework.
>>
>>     draft-ietf-sfc-multi-layer-oam does not reference any other SFC
>>     I-Ds. It does not build upon existing work in progress, and
>>     instead invents a new protocol with RFC8300 as the only Normative
>>     reference from SFC.
>>
>>     The draft-ietf-sfc-oam-framework at
>>     https://tools.ietf.org/html/draft-ietf-sfc-oam-framework-06 takes
>>     a holistic approach of including an analysis (selecting only some
>>     section titles):
>>     4.  SFC OAM Functions . . . . . . . . . . . . . . . . . . . . . .   8
>>     5.  Gap Analysis  . . . . . . . . . . . . . . . . . . . . . . . .  11
>>     5.1.  Existing OAM Functions  . . . . . . . . . . . . . . . . .  11
>>     5.2.  Missing OAM Functions . . . . . . . . . . . . . . . . . .  12
>>     6.4.  OAM Toolset applicability . . . . . . . . . . . . . . . .  13
>>            6.4.1.  ICMP Applicability  . . . . . . . . . . . . . . . .
>>     .  13
>>
>>     This analysis ought to guide protocol definition.
>>
>>     Question: Can this draft consider existing protocols and gap
>>     performed before re-inventing? Specifically Normatively cite the
>>     SFC OAM Framework and see where reuse is best?
>>
>>
>>     3. Existing implementation of OAM functions.
>>
>>     Hows does this draft work with existing OAM functions with
>>     existing implementation, such as
>>     https://tools.ietf.org/html/draft-penno-sfc-trace-03 ? The fact
>>     that the draft is expired does not mean the implementation is uncoded.
>>
>>
>>     Many thanks,
>>
>>     — Carlos Pignataro
>>
>>>     On May 9, 2019, at 1:31 AM, Greg Mirsky <[e-mail]
>>>     <mailto:[e-mail]>> wrote:
>>>
>>>     Dear All,
>>>     the update to the draft addresses the comment received from Joel
>>>     at the meeting in Prague:
>>>     - Joel: if we get an echo request we can't parse, how do we know
>>>     that it is an echo request, and do we have the information to
>>>     return it to the correct source?
>>>     - Greg: we will clarify this in the draft. It has to practical so
>>>     the sender can understand the situation.. We introduced two
>>>     classes of TLVs: mandatory and optional. Will add clearer text.
>>>
>>>     A new TLV, Errored TLVs, introduced to be optionally used to pass
>>>     in an echo reply mandatory TLVs that were not understood because
>>>     either the implementation on the receiver does not support them
>>>     or couldn't parse them correctly.
>>>
>>>     Also, please review the update to the interpretation of O-bit and
>>>     the value of the Next Protocol field to address Adrian's comments
>>>     at the meeting in Bangkok:
>>>     The rules of
>>>        interpreting the values of O bit and the Next Protocol field
>>>     are as
>>>        follows:
>>>
>>>        o  O bit set, and the Next Protocol value is not one of
>>>     identifying
>>>           active or hybrid OAM protocol (per [RFC7799] definitions),
>>>     e.g.,
>>>           defined in this specification Active SFC OAM - a Fixed-Length
>>>           Context Header or Variable-Length Context Header(s) contain OAM
>>>           command or data.  and the type of payload determined by the
>>>     Next
>>>           Protocol field;
>>>
>>>        o  O bit set, and the Next Protocol value is one of identifying
>>>           active or hybrid OAM protocol - the payload that immediately
>>>           follows SFC NSH contains OAM command or data;
>>>
>>>        o  O bit is clear - no OAM in a Fixed-Length Context Header or
>>>           Variable-Length Context Header(s) and the payload determined by
>>>           the value of the Next Protocol field;
>>>
>>>        o  O bit is clear and the Next Protocol value is one of
>>>     identifying
>>>           active or hybrid OAM protocol MUST be identified and
>>>     reported as
>>>           the erroneous combination.  An implementation MAY have
>>>     control to
>>>           enable processing of the OAM payload.
>>>
>>>        From the above-listed rules follows the recommendation to avoid
>>>        combination of OAM in a Fixed-Length Context Header or Variable-
>>>        Length Context Header(s) and in the payload immediately
>>>     following the
>>>        SFC NSH because there is no unambiguous way to identify such
>>>        combination using the O bit and the Next Protocol field.
>>>
>>>     Regards,
>>>     Greg
>>>
>>>     ---------- Forwarded message ---------
>>>     From: <[e-mail] <mailto:[e-mail]>>
>>>     Date: Wed, May 8, 2019 at 10:21 PM
>>>     Subject: New Version Notification for
>>>     draft-ietf-sfc-multi-layer-oam-03.txt
>>>     To: <[e-mail] <mailto:[e-mail]>>, Gregory
>>>     Mirsky <[e-mail] <mailto:[e-mail]>>,
>>>     Bhumip Khasnabish <[e-mail] <mailto:[e-mail]>>,
>>>     Wei Meng <[e-mail] <mailto:meng.wei2@zte..com.cn>>,
>>>     Cui(Linda) Wang <[e-mail]
>>>     <mailto:[e-mail]>>
>>>
>>>
>>>
>>>     A new version of I-D, draft-ietf-sfc-multi-layer-oam-03.txt
>>>     has been successfully submitted by Greg Mirsky and posted to the
>>>     IETF repository.
>>>
>>>     Name:           draft-ietf-sfc-multi-layer-oam
>>>     Revision:       03
>>>     Title:          Active OAM for Service Function Chains in Networks
>>>     Document date:  2019-05-08
>>>     Group:          sfc
>>>     Pages:          18
>>>     URL:
>>>     https://www.ietf.org/internet-drafts/draft-ietf-sfc-multi-layer-oam-03.txt
>>>     Status:
>>>     https://datatracker.ietf.org/doc/draft-ietf-sfc-multi-layer-oam/
>>>     Htmlized:
>>>     https://tools.ietf.org/html/draft-ietf-sfc-multi-layer-oam-03
>>>     Htmlized:
>>>     https://datatracker.ietf.org/doc/html/draft-ietf-sfc-multi-layer-oam
>>>     Diff:
>>>     https://www.ietf.org/rfcdiff?url2=draft-ietf-sfc-multi-layer-oam-03
>>>
>>>     Abstract:
>>>        A set of requirements for active Operation, Administration and
>>>        Maintenance (OAM) of Service Function Chains (SFCs) in networks is
>>>        presented.  Based on these requirements an encapsulation of active
>>>        OAM message in SFC and a mechanism to detect and localize defects
>>>        described.  Also, this document updates RFC 8300 in the
>>>     definition of
>>>        O (OAM) bit in the Network Service Header (NSH) and defines
>>>     how the
>>>        active OAM message identified in SFC NSH.
>>>
>>>
>>>
>>>
>>>     Please note that it may take a couple of minutes from the time of
>>>     submission
>>>     until the htmlized version and diff are available at
>>>     tools.ietf.org <http://tools.ietf.org/>.
>>>
>>>     The IETF Secretariat
>>>
>>>     _______________________________________________
>>>     sfc mailing list
>>>     [e-mail] <mailto:[e-mail]>
>>>     https://www.ietf.org/mailman/listinfo/sfc
>>
> 
> 
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