Re: [ippm] [sfc] WGLC for https://datatracker.ietf.org/doc/draft-ietf-sfc-ioam-nsh/

Shwetha Bhandari <shwetha.bhandari@thoughtspot.com> Thu, 14 April 2022 10:06 UTC

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From: Shwetha Bhandari <shwetha.bhandari@thoughtspot.com>
Date: Thu, 14 Apr 2022 15:35:41 +0530
Message-ID: <CAMFZu3N5+GdFk13oWbi8F1qhgRNsKpSFwza61SG2oeMW9TvaLQ@mail.gmail.com>
To: Greg Mirsky <gregimirsky@gmail.com>
Cc: Med Boucadair <mohamed.boucadair@orange.com>, "Frank Brockners (fbrockne)" <fbrockne=40cisco.com@dmarc.ietf.org>, "sfc-chairs@ietf.org" <sfc-chairs@ietf.org>, "sfc@ietf.org" <sfc@ietf.org>, "ippm@ietf.org" <ippm@ietf.org>, James Guichard <james.n.guichard@futurewei.com>, Tal Mizrahi <tal.mizrahi.phd@gmail.com>, "draft-ietf-sfc-ioam-nsh@ietf.org" <draft-ietf-sfc-ioam-nsh@ietf.org>
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Subject: Re: [ippm] [sfc] WGLC for https://datatracker.ietf.org/doc/draft-ietf-sfc-ioam-nsh/
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Hi Med, Greg,

How about this text :

“The O-bit MUST be handled following the rules in and any updates
to [RFC8300] ."

Given that I-D.ietf-sfc-oam-packet  will update RF8300 and there could be
others in future?

Thanks,
Shwetha

On Tue, Apr 12, 2022 at 9:24 PM Greg Mirsky <gregimirsky@gmail.com> wrote:

> Hi Shwetha,
> I believe that the text you've quoted is helpful. I would suggest changing
> references from [RFC8300] to [I-D.ietf-sfc-oam-packet] throughout that
> paragraph.
>
> Regards,
> Greg
>
> On Tue, Apr 12, 2022 at 7:56 AM Shwetha Bhandari <
> shwetha.bhandari@thoughtspot.com> wrote:
>
>> Med,
>>
>> Thanks for the details: this is exactly what we had before the latest
>> revision:
>>
>> 4.2 <https://urldefense.com/v3/__https://datatracker.ietf.org/doc/html/draft-ietf-sfc-ioam-nsh-06*section-4.2__;Iw!!MZ3Fw45to5uY!NBsrzhHEf0Y_-Sindy74K4QDA6EWJjx35STSH-UxEi3eYIX0GVli9Sn1azrOPJVcI2qUzWfezK_1D2RpyFB_FOIpJPfzrvI$>.  IOAM and the use of the NSH O-bit
>>
>>    [RFC8300] defines an "O bit" for OAM packets.  Per [RFC8300 <https://urldefense.com/v3/__https://datatracker.ietf.org/doc/html/rfc8300__;!!MZ3Fw45to5uY!NBsrzhHEf0Y_-Sindy74K4QDA6EWJjx35STSH-UxEi3eYIX0GVli9Sn1azrOPJVcI2qUzWfezK_1D2RpyFB_FOIpEB5AbbE$>] the O
>>    bit must be set for OAM packets and must not be set for non-OAM
>>    packets.  Packets with IOAM data included MUST follow this
>>    definition, i.e. the O bit MUST NOT be set for regular customer
>>    traffic which also carries IOAM data and the O bit MUST be set for
>>    OAM packets which carry only IOAM data without any regular data
>>    payload.
>>
>>
>> This was removed as per the discussion in this thread. Please check
>> https://mailarchive.ietf.org/arch/msg/sfc/srMit5zE8UseNOhxknAw_dqvj6M/
>> <https://urldefense.com/v3/__https://mailarchive.ietf.org/arch/msg/sfc/srMit5zE8UseNOhxknAw_dqvj6M/__;!!MZ3Fw45to5uY!NBsrzhHEf0Y_-Sindy74K4QDA6EWJjx35STSH-UxEi3eYIX0GVli9Sn1azrOPJVcI2qUzWfezK_1D2RpyFB_FOIp-CeLfeA$>
>>
>> It looks like we are going in a loop here. This definition of SFC OAM
>> packet to include the OAM data that comes in inner packets via the next
>> protocol header chain is introduced in draft-ietf-sfc-oam-packet to update
>> the RFC8300.
>> Jim, What are you thoughts on this? Should we reintroduce the above text ?
>>
>> Thanks,
>> Shwetha
>>
>>
>>
>> On Tue, Apr 12, 2022 at 8:09 PM <mohamed.boucadair@orange.com> wrote:
>>
>>> Hi Franck,
>>>
>>>
>>>
>>> Thank you for the clarification even if I don’t think there is a
>>> confusion.
>>>
>>>
>>>
>>> Please note that SFC OAM packet is defined as follows:
>>>
>>>
>>>
>>> ==
>>>
>>>       Such a packet
>>>
>>>       is any NSH-encapsulated packet that exclusively includes OAM data.
>>>
>>>       An OAM data can be included in the Fixed-Length Context Header,
>>>
>>>       optional Context Headers, and/or the inner packet.
>>>
>>> ==
>>>
>>>
>>>
>>> Things are pretty clear (as per draft-ietf-sfc-oam-packet) that the O
>>> bit must be unset when IOAM data is included + user data.
>>>
>>>
>>>
>>> The concern I had is that you are pointing to RFC8300 for the IOAM next
>>> protocol, which makes both “none” (i.e., no payload) and IOAM (as you
>>> request a new code) legitimate values.
>>>
>>>
>>>
>>> Cheers,
>>>
>>> Med
>>>
>>>
>>>
>>> *De :* sfc <sfc-bounces@ietf.org> *De la part de* Frank Brockners
>>> (fbrockne)
>>> *Envoyé :* mardi 12 avril 2022 13:55
>>> *À :* BOUCADAIR Mohamed INNOV/NET <mohamed.boucadair@orange.com>om>;
>>> Shwetha Bhandari <shwetha.bhandari@thoughtspot.com>om>; Greg Mirsky <
>>> gregimirsky@gmail.com>
>>> *Cc :* sfc-chairs@ietf.org; sfc@ietf.org; ippm@ietf.org; James Guichard
>>> <james.n.guichard@futurewei.com>om>; Tal Mizrahi <tal.mizrahi.phd@gmail.com>om>;
>>> draft-ietf-sfc-ioam-nsh@ietf.org
>>> *Objet :* Re: [sfc] WGLC for
>>> https://datatracker.ietf.org/doc/draft-ietf-sfc-ioam-nsh/
>>> <https://urldefense.com/v3/__https://datatracker.ietf.org/doc/draft-ietf-sfc-ioam-nsh/__;!!MZ3Fw45to5uY!JpBZ4H2-MNm5lJDGjooVj_3Sq-aX7gdh5qeoNPyZ69CXOFRhgdYmSOyreClzKvZDgPAiwaGN2YTO2qUw70GqHI4QEKQpGnBw0LXBXQ$>
>>>
>>>
>>>
>>> Hi Med,
>>>
>>>
>>>
>>> Sorry for arriving late to the party. Reading through your message
>>> below, there seems to be a confusion about the scope and concept of
>>> different OAM mechanisms.
>>>
>>>
>>>
>>> IOAM is scoped and designed to be protocol agnostic. IOAM data can be
>>> encapsulated into various protocols – and NSH is one example – but there is
>>> no semantic link between IOAM and the protocol used to encapsulate IOAM
>>> data.
>>>
>>>
>>>
>>> Protocols can have their protocol specific OAM methods and solutions,
>>> like SFC OAM. Those protocol specific solutions (like SFC OAM as an
>>> example) are orthogonal to IOAM from a concept and scope perspective.
>>>
>>>
>>>
>>> From an SFC OAM perspective, your draft-ietf-sfc-oam-packet-00 clearly
>>> and rightly states that “O bit: Setting this bit indicates an SFC OAM
>>> packet.” The O bit is about SFC OAM, and as such is orthogonal to “anything
>>> IOAM”. In earlier versions of draft-ietf-sfc-ioam-nsh we had text which
>>> stated that the O bit remains unchanged whether IOAM is present or not. To
>>> avoid any confusion, in -08 we removed this statement – just to make it
>>> crystal clear that there is no link between “IOAM” and “SFC OAM”.
>>>
>>>
>>>
>>> In addition, I don’t think that draft-ietf-sfc-ioam-nsh would be the
>>> appropriate place to discuss and restrict deployment options. E.g., I’m not
>>> sure why we’d want to restrict a deployment to using a single IOAM header
>>> only. E.g., one could think of using different headers for different
>>> namespaces or groups of namespaces for operational reasons. IMHO, such a
>>> discussion – if we really need it - would belong into
>>> draft-ietf-ippm-ioam-deployment, rather than into a draft that defines the
>>> encap of IOAM into NSH.
>>>
>>>
>>>
>>> Hope this clarifies things – and we can finish up
>>> draft-ietf-sfc-ioam-nsh :-).
>>>
>>>
>>>
>>> Cc’ing the ippm working group as an FYI.
>>>
>>>
>>>
>>> Thanks & Cheers, Frank
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> *From:* mohamed.boucadair@orange.com <mohamed.boucadair@orange.com>
>>> *Sent:* Monday, 4 April 2022 07:40
>>> *To:* Shwetha Bhandari <shwetha.bhandari@thoughtspot.com>om>; Greg Mirsky <
>>> gregimirsky@gmail.com>
>>> *Cc:* sfc-chairs@ietf.org; Frank Brockners (fbrockne) <
>>> fbrockne@cisco.com>gt;; sfc@ietf.org; James Guichard <
>>> james.n.guichard@futurewei.com>gt;; Tal Mizrahi <tal.mizrahi.phd@gmail.com>om>;
>>> draft-ietf-sfc-ioam-nsh@ietf.org
>>> *Subject:* RE: [sfc] WGLC for
>>> https://datatracker.ietf.org/doc/draft-ietf-sfc-ioam-nsh/
>>> <https://urldefense.com/v3/__https://datatracker.ietf.org/doc/draft-ietf-sfc-ioam-nsh/__;!!MZ3Fw45to5uY!JpBZ4H2-MNm5lJDGjooVj_3Sq-aX7gdh5qeoNPyZ69CXOFRhgdYmSOyreClzKvZDgPAiwaGN2YTO2qUw70GqHI4QEKQpGnBw0LXBXQ$>
>>>
>>>
>>>
>>> Hi Shwetha, all,
>>>
>>>
>>>
>>> I agree with Greg that a statement is needed to be added to
>>> draft-ietf-sfc-oam-packet.
>>>
>>>
>>>
>>> For example, the current text says the following:
>>>
>>>
>>>
>>>       Next Protocol:  8-bit unsigned integer that determines the type of
>>>
>>>          header following IOAM.  The semantics of this field are
>>>
>>>          identical to the Next Protocol field in [RFC8300
>>> <https://urldefense.com/v3/__https://datatracker.ietf.org/doc/html/rfc8300__;!!MZ3Fw45to5uY!JpBZ4H2-MNm5lJDGjooVj_3Sq-aX7gdh5qeoNPyZ69CXOFRhgdYmSOyreClzKvZDgPAiwaGN2YTO2qUw70GqHI4QEKQpGnDoYxXlRw$>
>>> ].
>>>
>>>
>>>
>>> which means that “None” is authorized. The O-bit must be set for such
>>> packets, while it should be unset for other values indicating user payload
>>> as per draft-ietf-sfc-oam-packet. Absent a pointer to the OAM packet, an
>>> implementer will have to guess the behavior to follow.
>>>
>>>
>>>
>>> BTW, the text quoted above when combined with:
>>>
>>>
>>>
>>>    IANA is requested to allocate protocol numbers for the following "NSH
>>>
>>>    Next Protocol" related to IOAM:
>>>
>>>
>>>
>>> …means that IOAM data can be encapsulated in IOAM data. I don’t think
>>> you want such a behavior. No?
>>>
>>>
>>>
>>> One last comment: please update the security considerations with
>>> NSH-specific considerations. An approach is to simply refer to Section 5 of
>>> draft-ietf-sfc-oam-packet.
>>>
>>>
>>>
>>> Cheers,
>>>
>>> Med
>>>
>>>
>>>
>>> *De :* sfc <sfc-bounces@ietf.org> *De la part de* Shwetha Bhandari
>>> *Envoyé :* lundi 4 avril 2022 02:41
>>> *À :* Greg Mirsky <gregimirsky@gmail.com>
>>> *Cc :* sfc-chairs@ietf.org; Frank Brockners (fbrockne) <
>>> fbrockne@cisco.com>gt;; sfc@ietf.org; James Guichard <
>>> james.n.guichard@futurewei.com>gt;; Tal Mizrahi <tal.mizrahi.phd@gmail.com>om>;
>>> draft-ietf-sfc-ioam-nsh@ietf.org
>>> *Objet :* Re: [sfc] WGLC for
>>> https://datatracker.ietf.org/doc/draft-ietf-sfc-ioam-nsh/
>>> <https://urldefense.com/v3/__https://datatracker.ietf.org/doc/draft-ietf-sfc-ioam-nsh/__;!!MZ3Fw45to5uY!JpBZ4H2-MNm5lJDGjooVj_3Sq-aX7gdh5qeoNPyZ69CXOFRhgdYmSOyreClzKvZDgPAiwaGN2YTO2qUw70GqHI4QEKQpGnBw0LXBXQ$>
>>>
>>>
>>>
>>> Hi Greg,
>>>
>>>
>>>
>>> Thanks for the feedback. From the discussion and Jim's feedback
>>>
>>>  "My only point was that in the case of IOAM the O-bit seems to be
>>> obsolete as you use the next protocol field rather than the context
>>> headers. It seems to me that the definition of the O-bit should be that if
>>> set then the context headers are used to obtain the OAM instructions."
>>>
>>> Which makes sense. The O-bit does not influence IOAM handling as it is
>>> carried as a next protocol.
>>>
>>> Hence the consideration section on O-bit is removed in the new revision.
>>> What do you think?
>>>
>>>
>>>
>>> Thanks
>>>
>>> Shwetha
>>>
>>>
>>>
>>> On Mon, Apr 4, 2022, 1:41 AM Greg Mirsky <gregimirsky@gmail.com> wrote:
>>>
>>> Hi Shwetha,
>>>
>>> thank you for your kind consideration of my comments and for
>>> thoroughly addressing those in the new version. I've noticed that you've
>>> decided to remove the discussion of the O bit in the NSH from the draft
>>> altogether. I think that it might be helpful to a reader if the document
>>> includes a short clarification and the reference to
>>> draft-ietf-sfc-oam-packet
>>> <https://urldefense.com/v3/__https:/www.ietf.org/id/draft-ietf-sfc-oam-packet-00.html__;!!MZ3Fw45to5uY!JYVtUwScRxFf7rDoRMpiv7YwbRTcaHXzsGIxr9eVEi_p_xSQUWAjDvFy_UhGEQbl8530VaLM0Tj7k5Wzu6YfUSVditWyZ_8$> like
>>> the following:
>>>
>>> For the IOAM functionality is SFC NSH described in this document the O
>>> bit
>>>
>>> in NSH MUST be set clear according to [I-D.ietf-sfc-oam-packet].
>>>
>>>
>>>
>>> Regards,
>>>
>>> Greg
>>>
>>>
>>>
>>> On Sun, Apr 3, 2022 at 1:06 AM Shwetha Bhandari <
>>> shwetha.bhandari@thoughtspot.com> wrote:
>>>
>>> Hi Jim, Greg,
>>>
>>>
>>>
>>> We have addressed the additional comments received in this discussion.
>>> Can you please take a look :
>>>
>>> https://www.ietf.org/rfcdiff?url2=draft-ietf-sfc-ioam-nsh-08.txt
>>> <https://urldefense.com/v3/__https:/www.ietf.org/rfcdiff?url2=draft-ietf-sfc-ioam-nsh-08.txt__;!!MZ3Fw45to5uY!JYVtUwScRxFf7rDoRMpiv7YwbRTcaHXzsGIxr9eVEi_p_xSQUWAjDvFy_UhGEQbl8530VaLM0Tj7k5Wzu6YfUSVd4KRpUCA$>
>>>
>>>
>>>
>>> Thanks,
>>>
>>> Shwetha
>>>
>>>
>>>
>>> On Thu, Feb 10, 2022 at 11:27 PM James Guichard <
>>> james.n.guichard@futurewei.com> wrote:
>>>
>>> Hi Shwetha,
>>>
>>>
>>>
>>> My only point was that in the case of IOAM the O-bit seems to be
>>> obsolete as you use the next protocol field rather than the context
>>> headers. It seems to me that the definition of the O-bit should be that if
>>> set then the context headers are used to obtain the OAM instructions.
>>> Currently that is not what 8300 says. As I said in my previous emails I
>>> would really like to hear the WGs opinion on what to do with the O-bit and
>>> we certainly need to reconcile the various documents to be following the
>>> same standard.
>>>
>>>
>>>
>>> Jim
>>>
>>>
>>>
>>> *From:* Shwetha Bhandari <shwetha.bhandari@thoughtspot.com>
>>> *Sent:* Wednesday, February 9, 2022 9:57 AM
>>> *To:* Greg Mirsky <gregimirsky@gmail.com>
>>> *Cc:* James Guichard <james.n.guichard@futurewei.com>om>;
>>> draft-ietf-sfc-ioam-nsh@ietf.org; sfc@ietf.org; sfc-chairs@ietf.org
>>> *Subject:* Re: [sfc] WGLC for
>>> https://datatracker.ietf.org/doc/draft-ietf-sfc-ioam-nsh/
>>> <https://urldefense.com/v3/__https:/datatracker.ietf.org/doc/draft-ietf-sfc-ioam-nsh/__;!!MZ3Fw45to5uY!f5SSgs9VAH1xxjFWgJMfr5ZlZH93z6GJlXoOgCmY8AVbjdeh2YlaUz632nE-HqDItW_8pjQ1iQ$>
>>>
>>>
>>>
>>> Hi Jim,
>>>
>>>
>>>
>>> On the O bit handling, are you suggesting that the O-bit for IOAM, that
>>> is carried as a next protocol following NSH header, is not applicable?
>>> Would removing the section on O-bit considerations resolve your concern?
>>>
>>>
>>>
>>> Hi Greg,
>>>
>>>
>>>
>>> >I have one more question. As the draft now mentions the option of using
>>> IOAM Direct Export to collect the IOAM data, it might be helpful reflecting
>>> that in the figure on p.2. I think that the caption "IOAM Option and Data
>>> Space" might be reworded to "IOAM Option and Optional Data Space".
>>>
>>> What are your thoughts?
>>>
>>> Yes, that will make it accurate. I will update the diagram and publish a
>>> new version.
>>>
>>>
>>>
>>> >I cannot find the text in the draft suggesting that an SFF that does
>>> not support IOAM may forward the packet with the NSH Next Protocol field
>>> equal to IOAM protocol identifier. Could you help me find it?
>>>
>>> Can you suggest text to help with this ? This would be a generic problem
>>> for NSH implementation when a next protocol is set to a value it does not
>>> understand. What should is recommended action in this situation?
>>>
>>>
>>>
>>>
>>>
>>> > For example, if the Loopback IOAM flag is set, the node is required to
>>> send a copy of the packet back to the IOAM encapsulating node. It is not
>>> clear to me how an SFF learns the identity of the IOAM encapsulating node
>>> and how it encapsulates the loopbacked packet. Can you help me find how it
>>> is supposed to work in the NSH?
>>>
>>>
>>> https://datatracker.ietf.org/doc/html/draft-ietf-ippm-ioam-flags#section-4.2
>>> <https://urldefense.com/v3/__https:/nam11.safelinks.protection.outlook.com/?url=https*3A*2F*2Fdatatracker.ietf.org*2Fdoc*2Fhtml*2Fdraft-ietf-ippm-ioam-flags*23section-4.2&data=04*7C01*7Cjames.n.guichard*40futurewei.com*7Ca5db82494c32402334fc08d9ebdc83cf*7C0fee8ff2a3b240189c753a1d5591fedc*7C1*7C0*7C637800154631120774*7CUnknown*7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0*3D*7C3000&sdata=zcOpC0Gzzi8xzhttBqWaeaU3pMd0KDo*2FZYdGsEPG0uE*3D&reserved=0__;JSUlJSUlJSUlJSUlJSUlJSUlJSUl!!MZ3Fw45to5uY!f5SSgs9VAH1xxjFWgJMfr5ZlZH93z6GJlXoOgCmY8AVbjdeh2YlaUz632nE-HqDItW_cH_6kAg$>
>>> :
>>>
>>>   A Loopback flag that is set indicates to the transit nodes processing
>>>
>>>    this option that they are to create a copy of the received packet and
>>>
>>>    send the copy back to the source of the packet.
>>>
>>> Given this is explained in the flag handling, do you see a need to
>>> define it again in NSH? IMHO the explanation of flag handling is quite
>>> generic for any packet based transport.
>>>
>>> Please share your thoughts and text suggestions to improve the draft for
>>> flag handling if it requires clarification.
>>>
>>>
>>>
>>>
>>>
>>> Thanks,
>>>
>>> Shwetha
>>>
>>>
>>>
>>> On Thu, Feb 3, 2022 at 6:48 AM Greg Mirsky <gregimirsky@gmail.com>
>>> wrote:
>>>
>>> Hi Shwetha,
>>>
>>> I have one more question. As the draft now mentions the option of using
>>> IOAM Direct Export to collect the IOAM data, it might be helpful reflecting
>>> that in the figure on p.2. I think that the caption "IOAM Option and Data
>>> Space" might be reworded to "IOAM Option and Optional Data Space".
>>>
>>> What are your thoughts?
>>>
>>>
>>>
>>> Regards,
>>>
>>> Greg
>>>
>>>
>>>
>>> On Wed, Feb 2, 2022 at 7:29 AM Shwetha Bhandari <
>>> shwetha.bhandari@thoughtspot.com> wrote:
>>>
>>> Hi Jim, Greg,
>>>
>>>
>>>
>>> Thanks for the follow up.
>>>
>>> 1) On O-bit: I am a bit confused about the O-bit feedback. Are you
>>> suggesting that it should not be a consideration for IOAM as it is handled
>>> as a next protocol and not as NSH context headers?
>>>
>>> What should a SFC element handle a packet containing IOAM as next header
>>> and does not implement IOAM and hence does not understand IOAM? I think
>>> O-bit helps in such situations to help such elements decide to drop or
>>> forward without processing the IOAM header.
>>>
>>> Let me know if that is not the case and if simply not considering O-bit
>>> in the context of IOAM is what you would recommend.
>>>
>>> 2) Active or Loopback flags
>>> <https://urldefense.com/v3/__https:/nam11.safelinks.protection.outlook.com/?url=https*3A*2F*2Furldefense.com*2Fv3*2F__https*3A*2F*2Fdatatracker.ietf.org*2Fdoc*2Fdraft-ietf-ippm-ioam-flags*2F__*3B!!MZ3Fw45to5uY!eu05ObEvXtnVX2OXFzl0g16vk36xSqTyjMReG_i6BavtG_ru2AnjQSjXHiZ_Ve3sBjJRuHMBUg*24&data=04*7C01*7Cjames.n.guichard*40futurewei.com*7Ca5db82494c32402334fc08d9ebdc83cf*7C0fee8ff2a3b240189c753a1d5591fedc*7C1*7C0*7C637800154631277005*7CUnknown*7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0*3D*7C3000&sdata=DvpZHlkn0PNCP5*2BzFQzGayutZGPUMxJXtPll6nR8Ay8*3D&reserved=0__;JSUlJSUlJSUlJSUlJSUlJSUlJSUlJSUlJSUl!!MZ3Fw45to5uY!f5SSgs9VAH1xxjFWgJMfr5ZlZH93z6GJlXoOgCmY8AVbjdeh2YlaUz632nE-HqDItW_4eduZWg$> -
>>> there is nothing specific for NSH on how the flags are to be handled.  The
>>> IOAM specific fields are to be handled as recommended by the respective
>>> IOAM drafts. Do you see any specific NSH considerations to be documented
>>> for IOAM fields?
>>>
>>>
>>>
>>> Thanks,
>>>
>>> Shwetha
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> On Tue, Feb 1, 2022 at 4:29 PM James Guichard <
>>> james.n.guichard@futurewei.com> wrote:
>>>
>>> Hi Shwetha & Greg,
>>>
>>>
>>>
>>> Thank you for the update.
>>>
>>>
>>>
>>> I still believe however that more work is necessary to reconcile how SFC
>>> OAM is supposed to work. RFC 8300 says:
>>>
>>>
>>>
>>>    O bit:  Setting this bit indicates an OAM packet (see [RFC6291
>>> <https://urldefense.com/v3/__https:/nam11.safelinks.protection.outlook.com/?url=https*3A*2F*2Furldefense.com*2Fv3*2F__https*3A*2F*2Fdatatracker.ietf.org*2Fdoc*2Fhtml*2Frfc6291__*3B!!MZ3Fw45to5uY!bzL7Vb_jHltGMCbCwne2rywfzpGjZW4o3fVr4clCr4Ir10KydDyJy5gHA8obfbMABJs06rKUNw*24&data=04*7C01*7Cjames.n.guichard*40futurewei.com*7Ca5db82494c32402334fc08d9ebdc83cf*7C0fee8ff2a3b240189c753a1d5591fedc*7C1*7C0*7C637800154631277005*7CUnknown*7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0*3D*7C3000&sdata=4wRcNgj93har9TlylAfX*2BtbW24VCqfneSZd0rD9CRzs*3D&reserved=0__;JSUlJSUlJSUlJSUlJSUlJSUlJSUlJSUlJSUl!!MZ3Fw45to5uY!f5SSgs9VAH1xxjFWgJMfr5ZlZH93z6GJlXoOgCmY8AVbjdeh2YlaUz632nE-HqDItW8b5uw-Yg$>
>>> ]).
>>>
>>>       The actual format and processing of SFC OAM packets is outside the
>>>
>>>       scope of this specification (for example, see [SFC-OAM-FRAMEWORK
>>> <https://urldefense.com/v3/__https:/nam11.safelinks.protection.outlook.com/?url=https*3A*2F*2Furldefense.com*2Fv3*2F__https*3A*2F*2Fdatatracker.ietf.org*2Fdoc*2Fhtml*2Frfc8300*ref-SFC-OAM-FRAMEWORK__*3BIw!!MZ3Fw45to5uY!bzL7Vb_jHltGMCbCwne2rywfzpGjZW4o3fVr4clCr4Ir10KydDyJy5gHA8obfbMABJsisioAug*24&data=04*7C01*7Cjames.n.guichard*40futurewei.com*7Ca5db82494c32402334fc08d9ebdc83cf*7C0fee8ff2a3b240189c753a1d5591fedc*7C1*7C0*7C637800154631277005*7CUnknown*7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0*3D*7C3000&sdata=A6fkAO8CwRJeW5tLLEpU0GhZrqsBOm7nUiE1QiMxwVQ*3D&reserved=0__;JSUlJSUlJSUlJSUqJSUlJSUlJSUlJSUlJSUl!!MZ3Fw45to5uY!f5SSgs9VAH1xxjFWgJMfr5ZlZH93z6GJlXoOgCmY8AVbjdeh2YlaUz632nE-HqDItW_b7k_TUA$>
>>> ]
>>>
>>>       for one approach).
>>>
>>>
>>>
>>>       The O bit MUST be set for OAM packets and MUST NOT be set for
>>>
>>>       non-OAM packets.
>>>
>>>
>>>
>>> If we look at RFC6291 it simply describes what OAM is supposed to mean
>>> and this is independent from SFC. The SFC-OAM-Framework (now RFC 8924) in
>>> section 6.3 says:
>>>
>>>
>>>
>>>    The Next Protocol field in the NSH header may be used to indicate
>>> what OAM function is intended
>>>
>>>    or what toolset is used.  Any other overlay encapsulations used at
>>> the service layer must have a
>>>
>>>    similar way to indicate the intended OAM function.
>>>
>>>
>>>
>>> So my reading of this is that if you take 8300 together with the
>>> framework then 1. The O-bit MUST be set for OAM packets, and 2. The Next
>>> Protocol field may or may not be used to indicate which OAM function is to
>>> be applied. From this I can determine that iOAM has taken the approach of
>>> using the next protocol field to indicate how to process the OAM packet and
>>> does NOT use the NSH context headers in any way shape or form. This seems
>>> consistent with the current definitions of the O-bit from RFC 8300 and
>>> processing guidelines from RFC 8924.
>>>
>>>
>>>
>>> However, your document says:
>>>
>>>
>>>
>>> *4.1
>>> <https://urldefense.com/v3/__https:/nam11.safelinks.protection.outlook.com/?url=https*3A*2F*2Furldefense.com*2Fv3*2F__https*3A*2F*2Fdatatracker.ietf.org*2Fdoc*2Fhtml*2Fdraft-ietf-sfc-ioam-nsh-07*section-4.1__*3BIw!!MZ3Fw45to5uY!bzL7Vb_jHltGMCbCwne2rywfzpGjZW4o3fVr4clCr4Ir10KydDyJy5gHA8obfbMABJtXMLMQUw*24&data=04*7C01*7Cjames.n.guichard*40futurewei.com*7Ca5db82494c32402334fc08d9ebdc83cf*7C0fee8ff2a3b240189c753a1d5591fedc*7C1*7C0*7C637800154631277005*7CUnknown*7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0*3D*7C3000&sdata=w3hANsqqvVWz5oeH*2BLfPwS*2Fxwh2hNERJwCw5zwdrAMA*3D&reserved=0__;JSUlJSUlJSUlJSUqJSUlJSUlJSUlJSUlJSUlJSU!!MZ3Fw45to5uY!f5SSgs9VAH1xxjFWgJMfr5ZlZH93z6GJlXoOgCmY8AVbjdeh2YlaUz632nE-HqDItW9Fp7_C8w$>.
>>> IOAM and the use of the NSH O-bit*
>>>
>>>
>>>
>>>    [RFC8300] defines an "O bit" for OAM packets.  Per [RFC8300
>>> <https://urldefense.com/v3/__https:/nam11.safelinks.protection.outlook.com/?url=https*3A*2F*2Furldefense.com*2Fv3*2F__https*3A*2F*2Fdatatracker.ietf.org*2Fdoc*2Fhtml*2Frfc8300__*3B!!MZ3Fw45to5uY!bzL7Vb_jHltGMCbCwne2rywfzpGjZW4o3fVr4clCr4Ir10KydDyJy5gHA8obfbMABJuMIrqXAQ*24&data=04*7C01*7Cjames.n.guichard*40futurewei.com*7Ca5db82494c32402334fc08d9ebdc83cf*7C0fee8ff2a3b240189c753a1d5591fedc*7C1*7C0*7C637800154631277005*7CUnknown*7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0*3D*7C3000&sdata=a*2BVevL6noSzqRzdWg6dscjiqevlLbxcgEdTEmfJAY7U*3D&reserved=0__;JSUlJSUlJSUlJSUlJSUlJSUlJSUlJSUlJSUl!!MZ3Fw45to5uY!f5SSgs9VAH1xxjFWgJMfr5ZlZH93z6GJlXoOgCmY8AVbjdeh2YlaUz632nE-HqDItW92fQLzlQ$>]
>>> the O
>>>
>>>    bit must be set for OAM packets and must not be set for non-OAM
>>>
>>>    packets.  Packets with IOAM data included MUST follow this
>>>
>>>    definition, i.e. the O bit MUST NOT be set for regular customer
>>>
>>>    traffic which also carries IOAM data and the O bit MUST be set for
>>>
>>>    OAM packets which carry only IOAM data without any regular data
>>>
>>>    payload.
>>>
>>>
>>>
>>> This text basically says that if the packet is customer traffic and
>>> happens to carry iOAM data then it is NOT an OAM packet.  What am I
>>> missing, customer traffic or not, both carry iOAM data so how are they
>>> different within an SFC domain?
>>>
>>>
>>>
>>> In addition to the above I will note that there is still a conflict with
>>> Greg’s draft namely this text from section 4:
>>>
>>>    *  O bit set and the "Next Protocol" value does not match the value
>>>
>>>       Active SFC OAM (TBA1), defined in Section 10.1
>>> <https://urldefense.com/v3/__https:/nam11.safelinks.protection.outlook.com/?url=https*3A*2F*2Furldefense.com*2Fv3*2F__https*3A*2F*2Fdatatracker.ietf.org*2Fdoc*2Fhtml*2Fdraft-ietf-sfc-multi-layer-oam*section-10.1__*3BIw!!MZ3Fw45to5uY!bzL7Vb_jHltGMCbCwne2rywfzpGjZW4o3fVr4clCr4Ir10KydDyJy5gHA8obfbMABJv1ohYIeg*24&data=04*7C01*7Cjames.n.guichard*40futurewei.com*7Ca5db82494c32402334fc08d9ebdc83cf*7C0fee8ff2a3b240189c753a1d5591fedc*7C1*7C0*7C637800154631277005*7CUnknown*7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0*3D*7C3000&sdata=HTLx6e4sQCvsjXZKxG1GA8XPvdswsQKEMIEABitkprw*3D&reserved=0__;JSUlJSUlJSUlJSUqJSUlJSUlJSUlJSUlJSUl!!MZ3Fw45to5uY!f5SSgs9VAH1xxjFWgJMfr5ZlZH93z6GJlXoOgCmY8AVbjdeh2YlaUz632nE-HqDItW-EwTZ2zw$>
>>> :
>>>
>>>
>>>
>>>          - An SFC NSH Context Header(s) contain an OAM processing
>>>
>>>          instructions or data.
>>>
>>>
>>>
>>>          - The "Next Protocol" field determines the type of the payload.
>>>
>>>
>>>
>>> The above text suggests to me that if the O-bit is set and the next
>>> protocol is not active SFC OAM then it is **required** that OAM data
>>> will be in the NSH context headers (which is not the case for iOAM) and the
>>> next protocol will indicate what follows the NSH header. While iOAM does
>>> follow the NSH header as indicated by the next protocol there is still an
>>> expectation that OAM is also carried in the NSH context headers. This seems
>>> to be in conflict with RFC 8300 AND RFC 8924.
>>>
>>>
>>>
>>> This of course is just my reading of the text and I would like to hear
>>> yours and other folks thoughts.
>>>
>>>
>>>
>>> Jim
>>>
>>>
>>>
>>> *From:* Shwetha Bhandari <shwetha.bhandari@thoughtspot.com>
>>> *Sent:* Monday, January 31, 2022 11:25 PM
>>> *To:* Greg Mirsky <gregimirsky@gmail.com>
>>> *Cc:* James Guichard <james.n.guichard@futurewei.com>om>;
>>> draft-ietf-sfc-ioam-nsh@ietf.org; sfc@ietf.org; sfc-chairs@ietf.org
>>> *Subject:* Re: [sfc] WGLC for
>>> https://datatracker.ietf.org/doc/draft-ietf-sfc-ioam-nsh/
>>> <https://urldefense.com/v3/__https:/nam11.safelinks.protection.outlook.com/?url=https*3A*2F*2Furldefense.com*2Fv3*2F__https*3A*2F*2Fdatatracker.ietf.org*2Fdoc*2Fdraft-ietf-sfc-ioam-nsh*2F__*3B!!MZ3Fw45to5uY!bzL7Vb_jHltGMCbCwne2rywfzpGjZW4o3fVr4clCr4Ir10KydDyJy5gHA8obfbMABJu3416GCQ*24&data=04*7C01*7Cjames.n.guichard*40futurewei.com*7Ca5db82494c32402334fc08d9ebdc83cf*7C0fee8ff2a3b240189c753a1d5591fedc*7C1*7C0*7C637800154631277005*7CUnknown*7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0*3D*7C3000&sdata=NKz8*2Fm*2Fh7WXjK0OP8NF4j5cQ*2FYgSrSMULRmDt*2FkX*2B10*3D&reserved=0__;JSUlJSUlJSUlJSUlJSUlJSUlJSUlJSUlJSUlJSUlJQ!!MZ3Fw45to5uY!f5SSgs9VAH1xxjFWgJMfr5ZlZH93z6GJlXoOgCmY8AVbjdeh2YlaUz632nE-HqDItW8EWrHtpA$>
>>>
>>>
>>>
>>> Hi Greg,
>>>
>>>
>>>
>>> Sorry for the late action on this.
>>> https://datatracker.ietf.org/doc/html/draft-ietf-sfc-ioam-nsh-07
>>> <https://urldefense.com/v3/__https:/nam11.safelinks.protection.outlook.com/?url=https*3A*2F*2Furldefense.com*2Fv3*2F__https*3A*2F*2Fnam11.safelinks.protection.outlook.com*2F*3Furl*3Dhttps*3A*2F*2Fdatatracker.ietf.org*2Fdoc*2Fhtml*2Fdraft-ietf-sfc-ioam-nsh-07*26data*3D04*7C01*7Cjames.n.guichard*40futurewei.com*7Caf9cde32be65486e459d08d9e53ac90c*7C0fee8ff2a3b240189c753a1d5591fedc*7C1*7C1*7C637792862928234181*7CUnknown*7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0*3D*7C3000*26sdata*3Dpl23JSzuzl5p2F8vooPyxVcUnWRdcWx*2F26MRFfJAIh4*3D*26reserved*3D0__*3BJSUlJSUlJSUlJSUlJSUlJSUlJSU!!MZ3Fw45to5uY!bzL7Vb_jHltGMCbCwne2rywfzpGjZW4o3fVr4clCr4Ir10KydDyJy5gHA8obfbMABJvEbkwM5w*24&data=04*7C01*7Cjames.n.guichard*40futurewei.com*7Ca5db82494c32402334fc08d9ebdc83cf*7C0fee8ff2a3b240189c753a1d5591fedc*7C1*7C0*7C637800154631277005*7CUnknown*7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0*3D*7C3000&sdata=dpoyXLu*2F9fGVSgLtewdI7wNfSPdrkhs7FtBdD3Aq7*2B0*3D&reserved=0__;JSUlJSUlJSUlJSUqKioqKiolJSoqKioqKioqKioqKiUlKiolJSUlJSUlJSUlJSUlJSUlJSUl!!MZ3Fw45to5uY!f5SSgs9VAH1xxjFWgJMfr5ZlZH93z6GJlXoOgCmY8AVbjdeh2YlaUz632nE-HqDItW9PuM1neA$>
>>> has been now posted with the edits per this discussion.
>>>
>>>
>>>
>>> Hi Jim,
>>>
>>>
>>>
>>> After Greg's review please let us know if the changes are good to
>>> progress the draft to the next step.
>>>
>>>
>>>
>>> Thanks,
>>>
>>> Shwetha
>>>
>>>
>>>
>>> On Wed, Oct 27, 2021 at 7:31 PM Greg Mirsky <gregimirsky@gmail.com>
>>> wrote:
>>>
>>> Hi Shwetha,
>>>
>>> thank you for the detailed response to my comments. Please feel free to
>>> share any updates you're considering for the next version. I'll be glad to
>>> work together on these.
>>>
>>> I have several follow-up notes in-lined below under the GIM>> tag.
>>>
>>>
>>>
>>> Regards,
>>>
>>> Greg
>>>
>>>
>>>
>>> On Tue, Oct 26, 2021 at 6:51 PM Shwetha Bhandari <
>>> shwetha.bhandari@thoughtspot.com> wrote:
>>>
>>> Hi Greg,
>>>
>>>
>>>
>>> Sorry for the very late reply. Please find responses to your comments
>>> inline @Shwetha:
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> On Wed, Sep 8, 2021 at 3:30 AM Greg Mirsky <gregimirsky@gmail.com>
>>> wrote:
>>>
>>> Dear Authors and All,
>>>
>>> I've read the current version of the draft and have some comments I'd
>>> like to share with you. I much appreciate your thoughts on where this work
>>> should go considering developments in other IETF WGs. Please find my notes
>>> and questions below:
>>>
>>>    - It is stated in the Abstract that:
>>>
>>>    In-situ Operations, Administration, and Maintenance (IOAM) records
>>>    operational and telemetry information in the packet while the packet
>>>    traverses a path between two points in the network.
>>>
>>> But that is the case only for the pre-allocated and incremental trace
>>> option types. The Direct Export option
>>> <https://urldefense.com/v3/__https:/nam11.safelinks.protection.outlook.com/?url=https*3A*2F*2Furldefense.com*2Fv3*2F__https*3A*2F*2Fnam11.safelinks.protection.outlook.com*2F*3Furl*3Dhttps*3A*2F*2Furldefense.com*2Fv3*2F__https*3A*2F*2Fdatatracker.ietf.org*2Fdoc*2Fdraft-ietf-ippm-ioam-direct-export*2F__*3B!!MZ3Fw45to5uY!db6q3n8-5YqHkLtf3wyeBoUpO72v7UzeDtfPNhyePahNAYMo9eFdQxxBWM4C7Z0OJKE0jphubQ*24*26data*3D04*7C01*7Cjames.n.guichard*40futurewei.com*7Caf9cde32be65486e459d08d9e53ac90c*7C0fee8ff2a3b240189c753a1d5591fedc*7C1*7C1*7C637792862928234181*7CUnknown*7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0*3D*7C3000*26sdata*3Di7sTr0MtC5qfzx3twOKSpbW8LkQJzsAJBxF*2FZPLUwKc*3D*26reserved*3D0__*3BJSUlJSUlJSUlJSUlJSUlJSUlJSUlJSUlJSUl!!MZ3Fw45to5uY!bzL7Vb_jHltGMCbCwne2rywfzpGjZW4o3fVr4clCr4Ir10KydDyJy5gHA8obfbMABJt0mRguJg*24&data=04*7C01*7Cjames.n.guichard*40futurewei.com*7Ca5db82494c32402334fc08d9ebdc83cf*7C0fee8ff2a3b240189c753a1d5591fedc*7C1*7C0*7C637800154631277005*7CUnknown*7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0*3D*7C3000&sdata=yVGpJY1y6dud5c44HOsptPjqEuXdNUa1DMzjAelvU5c*3D&reserved=0__;JSUlJSUlJSUlJSUqKioqKioqKioqKioqJSUqKioqKioqKioqKiolJSoqJSUlJSUlJSUlJSUlJSUlJSU!!MZ3Fw45to5uY!f5SSgs9VAH1xxjFWgJMfr5ZlZH93z6GJlXoOgCmY8AVbjdeh2YlaUz632nE-HqDItW-BwxdRIg$>
>>> does not write telemetry data into the data packet itself but export
>>> telemetry information in a specially constructed packet.
>>>
>>> And as we are talking about different IOAM trace options, the
>>> question of the scope of this document seems appropriate. There is a
>>> WGLC on two IOAM documents
>>> <https://urldefense.com/v3/__https:/nam11.safelinks.protection.outlook.com/?url=https*3A*2F*2Furldefense.com*2Fv3*2F__https*3A*2F*2Fnam11.safelinks.protection.outlook.com*2F*3Furl*3Dhttps*3A*2F*2Furldefense.com*2Fv3*2F__https*3A*2F*2Fmailarchive.ietf.org*2Farch*2Fmsg*2Fippm*2FA0OcGQ5LlNjnjfRVp_iUTMYMrcs*2F__*3B!!MZ3Fw45to5uY!db6q3n8-5YqHkLtf3wyeBoUpO72v7UzeDtfPNhyePahNAYMo9eFdQxxBWM4C7Z0OJKHOndSFRg*24*26data*3D04*7C01*7Cjames.n.guichard*40futurewei.com*7Caf9cde32be65486e459d08d9e53ac90c*7C0fee8ff2a3b240189c753a1d5591fedc*7C1*7C1*7C637792862928234181*7CUnknown*7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0*3D*7C3000*26sdata*3DcHtvsgDl*2FuzSv70oS9LN5l2o5nEIwiKHDZ1sfiFJCrE*3D*26reserved*3D0__*3BJSUlJSUlJSUlJSUlJSUlJSUlJSUlJSUlJSUlJSU!!MZ3Fw45to5uY!bzL7Vb_jHltGMCbCwne2rywfzpGjZW4o3fVr4clCr4Ir10KydDyJy5gHA8obfbMABJu2SsX7cg*24&data=04*7C01*7Cjames.n.guichard*40futurewei.com*7Ca5db82494c32402334fc08d9ebdc83cf*7C0fee8ff2a3b240189c753a1d5591fedc*7C1*7C0*7C637800154631277005*7CUnknown*7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0*3D*7C3000&sdata=Y*2BwywuTSj4SpugrjmDTquAY0MZWKoT43CMjsyha*2FnOc*3D&reserved=0__;JSUlJSUlJSUlJSUqKioqKioqKioqKioqKiolJSoqKioqKioqKioqKiUlKiolJSUlJSUlJSUlJSUlJSUlJSUl!!MZ3Fw45to5uY!f5SSgs9VAH1xxjFWgJMfr5ZlZH93z6GJlXoOgCmY8AVbjdeh2YlaUz632nE-HqDItW-FRADPxg$>
>>> active through September 15th at the IPPM WG. I believe that it would be
>>> beneficial if we had a single document that describes the applicability of
>>> IOAM in all its functionality defined by documents in IPPM WG. Of course,
>>> that cannot be a moving target as that would not be helpful. But since the
>>> IPPM WG discusses the progress of two IOAM documents, it could be a great
>>> time to address the applicability of the Direct Export trace type
>>> <https://urldefense.com/v3/__https:/nam11.safelinks.protection.outlook.com/?url=https*3A*2F*2Furldefense.com*2Fv3*2F__https*3A*2F*2Fnam11.safelinks.protection.outlook.com*2F*3Furl*3Dhttps*3A*2F*2Furldefense.com*2Fv3*2F__https*3A*2F*2Fdatatracker.ietf.org*2Fdoc*2Fdraft-ietf-ippm-ioam-direct-export*2F__*3B!!MZ3Fw45to5uY!db6q3n8-5YqHkLtf3wyeBoUpO72v7UzeDtfPNhyePahNAYMo9eFdQxxBWM4C7Z0OJKE0jphubQ*24*26data*3D04*7C01*7Cjames.n.guichard*40futurewei.com*7Caf9cde32be65486e459d08d9e53ac90c*7C0fee8ff2a3b240189c753a1d5591fedc*7C1*7C1*7C637792862928234181*7CUnknown*7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0*3D*7C3000*26sdata*3Di7sTr0MtC5qfzx3twOKSpbW8LkQJzsAJBxF*2FZPLUwKc*3D*26reserved*3D0__*3BJSUlJSUlJSUlJSUlJSUlJSUlJSUlJSUlJSUl!!MZ3Fw45to5uY!bzL7Vb_jHltGMCbCwne2rywfzpGjZW4o3fVr4clCr4Ir10KydDyJy5gHA8obfbMABJt0mRguJg*24&data=04*7C01*7Cjames.n.guichard*40futurewei.com*7Ca5db82494c32402334fc08d9ebdc83cf*7C0fee8ff2a3b240189c753a1d5591fedc*7C1*7C0*7C637800154631277005*7CUnknown*7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0*3D*7C3000&sdata=yVGpJY1y6dud5c44HOsptPjqEuXdNUa1DMzjAelvU5c*3D&reserved=0__;JSUlJSUlJSUlJSUqKioqKioqKioqKioqJSUqKioqKioqKioqKiolJSoqJSUlJSUlJSUlJSUlJSUlJSU!!MZ3Fw45to5uY!f5SSgs9VAH1xxjFWgJMfr5ZlZH93z6GJlXoOgCmY8AVbjdeh2YlaUz632nE-HqDItW-BwxdRIg$>
>>> and Loopback and Active flags defined in draft-ietf-ippm-ioam-flags
>>> <https://urldefense.com/v3/__https:/nam11.safelinks.protection.outlook.com/?url=https*3A*2F*2Furldefense.com*2Fv3*2F__https*3A*2F*2Fnam11.safelinks.protection.outlook.com*2F*3Furl*3Dhttps*3A*2F*2Furldefense.com*2Fv3*2F__https*3A*2F*2Fdatatracker.ietf.org*2Fdoc*2Fdraft-ietf-ippm-ioam-flags*2F__*3B!!MZ3Fw45to5uY!db6q3n8-5YqHkLtf3wyeBoUpO72v7UzeDtfPNhyePahNAYMo9eFdQxxBWM4C7Z0OJKHO7lReVw*24*26data*3D04*7C01*7Cjames.n.guichard*40futurewei.com*7Caf9cde32be65486e459d08d9e53ac90c*7C0fee8ff2a3b240189c753a1d5591fedc*7C1*7C1*7C637792862928234181*7CUnknown*7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0*3D*7C3000*26sdata*3D1kqtcu3xjl1C7ytQ*2BoaKdiQN96rQt94e1S2ElC0nD3M*3D*26reserved*3D0__*3BJSUlJSUlJSUlJSUlJSUlJSUlJSUlJSUlJSUl!!MZ3Fw45to5uY!bzL7Vb_jHltGMCbCwne2rywfzpGjZW4o3fVr4clCr4Ir10KydDyJy5gHA8obfbMABJt8NqRRKg*24&data=04*7C01*7Cjames.n.guichard*40futurewei.com*7Ca5db82494c32402334fc08d9ebdc83cf*7C0fee8ff2a3b240189c753a1d5591fedc*7C1*7C0*7C637800154631277005*7CUnknown*7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0*3D*7C3000&sdata=zzcnXlewWKrtEDv4BmsNNk4pvDlMKNKvPzBZ2dZJm5k*3D&reserved=0__;JSUlJSUlJSUlJSUqKioqKioqKioqKioqJSUqKioqKioqKioqKiolJSoqJSUlJSUlJSUlJSUlJSUlJSU!!MZ3Fw45to5uY!f5SSgs9VAH1xxjFWgJMfr5ZlZH93z6GJlXoOgCmY8AVbjdeh2YlaUz632nE-HqDItW-gOuTqwg$>.
>>> It would be concerning to have more than one SFC document describing the
>>> applicability of the generic IOAM mechanisms
>>>
>>>
>>>
>>> Shwetha> This is a fair point. We will revise the  draft with text in
>>> the abstract and Section 3 IOAM-Type to be updated to include the usage
>>> of trace and DEX options.  The encapsulation of IOAM options within NSH
>>> itself in its current form already supports all the IOAM Option Type
>>> defined both from draft-ietf-ippm-ioam-data and draft-ietf-ippm-ioam-direct-export
>>> along with the flags supported within the options. Hence the
>>> IOAM-data-field definitions in the draft will remain unchanged.
>>>
>>> GIM>> I agree that the definitions of the IOAM data-fields are invariant
>>> in various data plane encapsulations. You likely follow the discussion of
>>> the IAOM Direct Export and IOAM flags on the IPPM WG list. I think that for
>>> SFC NSH, IOAM Direct Export could be as simple as "use the local policy".
>>> The applicability of the Loopback and Active flags seems to require
>>> detailed explanation by SFP actors.
>>>
>>>
>>>
>>>
>>>
>>>
>>>    - The location of the IOAM header in the SFC NSH-encapsulated packet
>>>    is defined in Section 3:
>>>
>>>    IOAM-Data-Fields are carried in NSH
>>>
>>>    using a next protocol header which follows the NSH MD context
>>>
>>>    headers.
>>>
>>> I've checked RFC 8300 but couldn't find it defines the Next Protocol
>>> header. Also, it appears that NSH Context headers are optional. Hence my
>>> question. Is the presence of an NSH Context header required when using
>>> IOAM? Could you clarify which mechanism is used to identify the payload of
>>> an SFC NSH-encapsulated packet as IOAM?
>>>
>>> Shwetha> We will reword it, it is not Next Protocol header but using
>>> IOAM as a Next Protocol as described in Section 4.1 and requested in IANA
>>> section. Following is the proposed text to align with the RFC 8300
>>> reference to context headers following base header and service path header:
>>>
>>> "The NSH is defined in [RFC8300].  IOAM-Data-Fields are carried in
>>> NSH using a next protocol to identify IOAM data fields that follows NSH
>>> context headers."
>>>
>>> GIM>> I think that RFC 8300 views data following Context Headers as NSH
>>> payload, not being "in NSH".
>>>
>>>
>>>    - If I understand the format of the IOAM header defined in Section 3
>>>    correctly, the header's length is limited by 1020 octets, while the
>>>    effective length containing IOAM options and data - 1016 octets. Is that
>>>    correct? What is the recommended technique of collecting IOAM data that
>>>    exceeds that limit?
>>>
>>> Shwetha > IOAM options inherently support specifying the size limits at
>>> the node that added the IOAM options. While operationalizing the solution
>>> the data types included and number of nodes expected to be adding the data
>>> should be selected. This is covered in deployment
>>> considerations draft-brockners-opsawg-ioam-deployment.
>>>
>>>
>>>    - In Section 4.1, I've found the text reflecting the history of the
>>>    discussion about how to carry the IOAM header using NSH encapsulation. As
>>>    the text has no normative value, I suggest moving it into an Appendix.
>>>
>>> Shwetha > Agreed, revised draft will have this section moved to
>>> Appendix.
>>>
>>> GIM>> Thank you.
>>>
>>>
>>>    - I find the rules of handling the O-bit in NSH listed in Section
>>>    4.2 inconsistent and confusing. The IOAM header is not part of NSH
>>>    encapsulation but is a part of the payload. But in one case, when user data
>>>    follows it, the O-bit must not be set as. If there's no user data after the
>>>    IOAM header, then the O-bit must be set. But from the perspective of NSH
>>>    encapsulation, it includes specially constructed data added for the sole
>>>    purpose of collecting OAM/telemetry information. Then, why, in one case,
>>>    the O-bit is cleared and in the other set if, in both cases, the
>>>    NSH-encapsulated packet is used to perform the OAM function?
>>>
>>> Shwetha > The reason for not setting the O-bit for packets that contains
>>> actual user data is because RFC 8300 has " SF/SFF/SFC Proxy/Classifier
>>> implementations that do not support
>>>
>>>       SFC OAM procedures SHOULD discard packets with O bit set". It will be undesirable to discard packets with O-bit set that carry user data as IOAM can be inserted insitu.
>>>
>>> For synthetic traffic created for OAM along with IOAM-data-fields in NSH following the NSH OAM function with 0-bit set is desirable.
>>>
>>>  GIM>> This is an interesting situation. I agree that there could be an
>>> SFC element not supporting "SFC OAM procedures" (not clear what these are).
>>> By the same token, would such SFC element support IOAM, be capable of
>>> processing IOAM without adverse impact to user data? I am not certain and
>>> it seems that it might be better to recommend that NSH packets with IOAM be
>>> dropped by an SFP element if it does not support "SFC OAM". What are your
>>> thoughts?
>>>
>>>
>>>
>>>
>>>
>>> Thanks,
>>>
>>> Shwetha
>>>
>>> I much appreciate your consideration of my comments and questions and
>>> looking forward to your feedback.
>>>
>>>
>>>
>>> Regards,
>>>
>>> Greg
>>>
>>>
>>>
>>> On Wed, Aug 18, 2021 at 5:32 AM James Guichard <
>>> james.n.guichard@futurewei.com> wrote:
>>>
>>> Dear WG:
>>>
>>>
>>>
>>> This email starts a 2 week Working Group Last Call for
>>> draft-ietf-sfc-ioam-nsh [1].
>>>
>>>
>>>
>>> Please read this document if you haven’t read the most recent version
>>> and send your comments to the SFC WG list no later than September 1st
>>> 2021.
>>>
>>>
>>>
>>> If you are raising a point which you expect will be specifically debated
>>> on the mailing list, consider using a specific email/thread for this point.
>>>
>>>
>>>
>>> Lastly, if you are an author or contributor please response to indicate
>>> whether you know of any undisclosed IPR related to this document.
>>>
>>>
>>>
>>> Thanks!
>>>
>>>
>>>
>>> Jim & Joel
>>>
>>>
>>>
>>> [1] https://datatracker.ietf.org/doc/draft-ietf-sfc-ioam-nsh/
>>> <https://urldefense.com/v3/__https:/nam11.safelinks.protection.outlook.com/?url=https*3A*2F*2Furldefense.com*2Fv3*2F__https*3A*2F*2Fnam11.safelinks.protection.outlook.com*2F*3Furl*3Dhttps*3A*2F*2Furldefense.com*2Fv3*2F__https*3A*2F*2Fdatatracker.ietf.org*2Fdoc*2Fdraft-ietf-sfc-ioam-nsh*2F__*3B!!MZ3Fw45to5uY!db6q3n8-5YqHkLtf3wyeBoUpO72v7UzeDtfPNhyePahNAYMo9eFdQxxBWM4C7Z0OJKHdTiRE6A*24*26data*3D04*7C01*7Cjames.n.guichard*40futurewei.com*7Caf9cde32be65486e459d08d9e53ac90c*7C0fee8ff2a3b240189c753a1d5591fedc*7C1*7C1*7C637792862928234181*7CUnknown*7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0*3D*7C3000*26sdata*3D9uDdhw0ViwBtWvn52V8UZ2G77lRnSye2Ols5z3U8QwQ*3D*26reserved*3D0__*3BJSUlJSUlJSUlJSUlJSUlJSUlJSUlJSUlJSU!!MZ3Fw45to5uY!bzL7Vb_jHltGMCbCwne2rywfzpGjZW4o3fVr4clCr4Ir10KydDyJy5gHA8obfbMABJv33kGkLw*24&data=04*7C01*7Cjames.n.guichard*40futurewei.com*7Ca5db82494c32402334fc08d9ebdc83cf*7C0fee8ff2a3b240189c753a1d5591fedc*7C1*7C0*7C637800154631277005*7CUnknown*7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0*3D*7C3000&sdata=S6sx7MrrVkzKepVgj45q*2F2KPZzBMyOFnol*2BMfgRQ730*3D&reserved=0__;JSUlJSUlJSUlJSUqKioqKioqKioqKioqJSUqKioqKioqKioqKiolJSolJSUlJSUlJSUlJSUlJSUlJSUl!!MZ3Fw45to5uY!f5SSgs9VAH1xxjFWgJMfr5ZlZH93z6GJlXoOgCmY8AVbjdeh2YlaUz632nE-HqDItW-FOmuSHA$>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
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>>>
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