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

["Carlos Pignataro (cpignata)" <[e-mail]>]

Joel,

In regards to the “Implementation Status” section, I am absolutely OK if the authors intentionally and deliberately choose not to include it and explain the rationale when asked, and clearly OK if there are no implementations.

My concern here is that neither of those two have been answered by an author yet. (1. Are there implementations? 2. What are the reason, many valid, for which an implementation section would not be added to this document) Instead they have been silently dropped twice, once during adoption call.

If you look at the other two questions I posted originally, they speak to a larger concern, which includes:
Q2 - many of these problems are solved with existing protocols, hence refer to the gap analysis in the ohm-framework, which is not even referenced.
Q3 - there are other coded solutions which are being ignored (e.g., trace route)

Best,

— Carlos Pignataro

On May 10, 2019, at 11:48 PM, Joel M. Halpern <[e-mail]<mailto:[e-mail]>> wrote:

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]> <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]> <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]>
   <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]> <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]> <mailto:[e-mail]>>, Gregory
   Mirsky <[e-mail]<mailto:[e-mail]> <mailto:[e-mail]>>,
   Bhumip Khasnabish <[e-mail]<mailto:[e-mail]> <mailto:[e-mail]>>,
   Wei Meng <[e-mail]<mailto:[e-mail]> <mailto:meng.wei2@zte..com.cn<http://com.cn/>>>,
   Cui(Linda) Wang <[e-mail]<mailto:[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.




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