Re: [Bier] BIERv6 and BIERin6 OAM support discussion

Gyan Mishra <hayabusagsm@gmail.com> Fri, 27 November 2020 04:19 UTC

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From: Gyan Mishra <hayabusagsm@gmail.com>
Date: Thu, 26 Nov 2020 23:18:50 -0500
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To: Greg Mirsky <gregimirsky@gmail.com>
Cc: BIER WG <bier@ietf.org>, Greg Shepherd <gjshep@gmail.com>, Michael McBride <michael.mcbride@futurewei.com>, Tianran Zhou <zhoutianran@huawei.com>, Tony Przygienda <tonysietf@gmail.com>, "Xiejingrong (Jingrong)" <xiejingrong@huawei.com>
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Subject: Re: [Bier] BIERv6 and BIERin6 OAM support discussion
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Greg

With BIERv6 the format is a bit different as we are encoding in an IPv6
extended header DOH options and not using the RFC 8296 Non MPLS BIER
encapsulation.  So the proto filed changes when we encoding BIER header
into DOH which is why it’s set to 0 and ignored upon transmission since
with IPv6 next header field is used.

See below excerpt that this is being updated in RFC 8296 section 2.1.2.

As BIER OAM is coupled into the BIER architecture, BIERv6 will support BIER
OAM using BIER ping by DOH encoding of BIER header and will fully support
the BIER OAM message format.

https://tools.ietf.org/html/draft-ietf-bier-pmmm-oam-08

https://tools.ietf.org/html/draft-ietf-bier-ping-07


Below is excerpt from section 3.1 top of page 6.


        Proto: SHOULD be set to 0 upon transmission and be ignored upon
        reception.  In BIERv6 encapsulation, the functionality of this
        6-bit Proto field is replaced by the Next Header field in
        Destination Options header or the last IPv6 extension header to
        indicate the type of the payload.  This updates section 2.1.2 of
        [RFC8296] <https://tools.ietf.org/html/rfc8296#section-2.1.2>
about Proto definition.  Next Header value in BIERv6
        encapsulation for common usage includes:

          Value 4 for IPv4 packet as BIERv6 payload.

          Value 41 for IPv6 packet as BIERv6 payload.

          Value 143 for Ethernet packet as BIERv6 payload.

        Multicast VPN (MVPN) service is considered as part of the BIER
        layering mode defined in [RFC8279
<https://tools.ietf.org/html/rfc8279>], and should be supported by
        BIERv6 encapsulation.  [I-D.xie-bier-ipv6-mvpn
<https://tools.ietf.org/html/draft-xie-bier-ipv6-encapsulation-08#ref-I-D.xie-bier-ipv6-mvpn>]
illustrates how
        MVPN is supported in BIERv6 encapsulation without using this
        Proto field.

        BIER-PING [I-D.ietf-bier-ping
<https://tools.ietf.org/html/draft-xie-bier-ipv6-encapsulation-08#ref-I-D.ietf-bier-ping>]
        is considered a useful function
        of the BIER architecture, and should be supported by BIERv6
        encapsulation.  How BIER-PING is supported in BIERv6
        encapsulation without using this Proto field is outside the
        scope of this document.



Kind Regards


Gyan



On Thu, Nov 26, 2020 at 9:21 PM Greg Mirsky <gregimirsky@gmail.com> wrote:

> Hi Tianran,
> thank you for your quick response. Yes, my question was in the
> relationship with the note at the closing of Section 3.1:
>         How BIER-PING is supported in BIERv6
>         encapsulation without using this Proto field is outside the
>         scope of this document.
> If I understand you correctly, the authors of BIERv6 don't consider
> supporting BIER OAM as defined in draft-ietf-bier-ping. Is that the
> authors' position?
> I agree with you that IP/UDP encapsulation can be used in BIERv6 but I
> need to note that because BIER Ping is defined with the use of only BIER
> OAM encapsulation, no UDP port has been requested from IANA.
>
> Regards,
> Greg
>
> On Thu, Nov 26, 2020 at 5:44 PM Tianran Zhou <zhoutianran@huawei.com>
> wrote:
>
>> Hi Greg,
>>
>>
>>
>> “How does BIERv6 support BIER OAM”?
>>
>>
>>
>> I may still not understand your question. But let me try to be clear.
>>
>> IMO, this question is just about the identifier + oam message. Right?
>>
>>
>>
>> We can use the same bier oam header/message as you pointed, and for ping,
>> bfd, stamp.
>>
>> The difference is only the identifier.
>>
>> Bierv6 use ip/udp encap, and use the udp port to identify the oam header.
>>
>>
>>
>> Cheers,
>>
>> Tianran
>>
>>
>>
>> *From:* Greg Mirsky [mailto:gregimirsky@gmail.com]
>> *Sent:* Friday, November 27, 2020 6:12 AM
>> *To:* Tianran Zhou <zhoutianran@huawei.com>
>> *Cc:* Gyan Mishra <hayabusagsm@gmail.com>om>; BIER WG <bier@ietf.org>rg>; Greg
>> Shepherd <gjshep@gmail.com>om>; Michael McBride <
>> michael.mcbride@futurewei.com>gt;; Tony Przygienda <tonysietf@gmail.com>om>;
>> Xiejingrong (Jingrong) <xiejingrong@huawei.com>
>> *Subject:* Re: BIERv6 and BIERin6 OAM support discussion
>>
>>
>>
>> Hi Tianran,
>>
>> you are right, IP/UDP encapsulation is one of the options to encapsulate
>> BIER active OAM messages and it was considered when we've worked on
>> draft-ietf-bier-ping
>> <https://www.ietf.org/archive/id/draft-ietf-bier-ping-07.txt> (the
>> updated version is coming soon). But we've decided to not use it and define
>> BIER OAM header (Section 3.1 of the draft-ietf-bier-ping):
>>
>>       0                   1                   2                   3
>>
>>       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
>>
>>      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>
>>      |  Ver  | Message Type  | Proto |             Reserved          |
>>
>>      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>
>>      |                        OAM Message Length                     |
>>
>>      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>
>>      ~                  Message Type Dependent Data                  ~
>>
>>      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>
>> BIER WG has agreed and that is now the encapsulation of BIER OAM whether
>> it is BIER Echo Request/Reply, a BFD Control message, or a STAMP'
>> Session-Sender's message. Hope that clarifies the context of my question
>> How does BIERv6 support BIER OAM?
>>
>>
>>
>> Regards,
>>
>> Greg
>>
>>
>>
>> On Wed, Nov 25, 2020 at 10:52 PM Tianran Zhou <zhoutianran@huawei.com>
>> wrote:
>>
>> Hi Greg,
>>
>>
>>
>> Thanks for your interest on OAM. Let me reply your question here.
>>
>>
>>
>> @Gyan, thanks for folking this thread.
>>
>>
>>
>> The way to encapsulate OAM message is very generic, just like MPLS ping
>> and MPLS p2mp ping.
>>
>> OAM message is in IP+UDP after Bier.
>>
>> A highlight of this way is it could also apply to draft-ietf-bier-php.
>>
>>
>>
>> Cheers,
>>
>> Tianran
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> *From:* Gyan Mishra [mailto:hayabusagsm@gmail.com]
>> *Sent:* Thursday, November 26, 2020 1:38 PM
>> *To:* BIER WG <bier@ietf.org>rg>; Greg Mirsky <gregimirsky@gmail.com>om>; Greg
>> Shepherd <gjshep@gmail.com>om>; Gyan Mishra <hayabusagsm@gmail.com>om>;
>> Michael McBride <michael.mcbride@futurewei.com>om>; Tianran Zhou <
>> zhoutianran@huawei.com>gt;; Tony Przygienda <tonysietf@gmail.com>om>;
>> Xiejingrong (Jingrong) <xiejingrong@huawei.com>
>> *Subject:* Re: BIERv6 and BIERin6 OAM support discussion
>>
>>
>>
>> Greg
>>
>>
>>
>> With RFC 8296 Non MPLS BIER Ethernet next header 0xAB37  and optIonal
>> BIERin6 encapsulation single hop or multi hop tunnel the BIER header is
>> present either after Ethernet header in the latter or after the IPv6 header
>> in BIERin6 and is present to encode OAM value for proto fied.
>>
>>
>>
>> With BIERv6 there is not any “BIER” encapsulation layer as the BIER
>> header is encoded in IPV6 extension header DOH header.  As it is not
>> encoded in the IPV6 packet header and is part of IPv6 header as is an
>> extension header, OAM will not work natively with BIERv6.
>>
>>
>>
>>
>>
>> Jingrong and Xuesong
>>
>>
>>
>> Please shed some light on how OAM would work with BIERv6?
>>
>>
>>
>> Thanks
>>
>>
>>
>> Gyan
>>
>>
>>
>> On Wed, Nov 25, 2020 at 11:47 PM Gyan Mishra <hayabusagsm@gmail.com>
>> wrote:
>>
>> RE: BIER in IPV6 environment OAM support
>>
>>
>>
>> ***Tonys email related to OAM requirement***
>>
>>
>>
>> Quick correction here as to OAM. OAM is worked on and multiple quite
>> extensive & well-written drafts dealing with OAM aspects are adopted/in
>> flight since quite a while (I count 4 adopted & 1 individual). BIER has
>> been specifically architected with multicast OAM in mind which is
>> non-trivial such as MTU discovery (we have 2 drafts for a good reason &
>> discussion is pending) and dealing with OAM when we're dealing with mp2mp
>> trees (which BIER basically is or can be used at). One of the reasons BIER
>> found interest in the set of people that need/like it is that they were
>> looking for very tight OAM guarantees in orders of microseconds and that
>> without highly specific hardware designed for it is very difficult (and
>> packet format, that's why OAM is first order citizen in BIER in terms of
>> bits provided e.g. for marking purposes and can be found in a very specific
>> offset. to support the OAM desired HW has to process and generate
>> sub-microseconds trains.
>>
>>
>>
>> As far as I saw there was not much on the radar in terms of anything
>> comparable in SRv6 OAM work beside "SID-ping" if the intention is to rely
>> on SRv6 to deal with that problem. But of course I may have missed some
>> draft. Even if they work on unicast OAM I may express my profound doubts
>> there will be interest or focus to solve OAM for SRv6 becoming a L3
>> multicast transport with the type of OAM BIER needs on top.
>>
>>
>>
>> As to desired OAM, I think we have an OAM requirements draft adopted with
>> quite a list of industry authors since quite a bit. this draft has WG
>> consensus and has to be satisfied.
>>
>>
>>
>>
>> https://datatracker.ietf.org/doc/draft-ietf-bier-oam-requirements/?include_text=1
>>
>>
>>
>> -- tony
>>
>>
>>
>> Greg Mirsky update request to BIER IPv6 Requirements draft:
>>
>>
>>
>> Dear All,
>>
>> I apologize for jumping into this discussion but have someone said "OAM"?
>> :)
>>
>> I much appreciate what our co-chair (and contributor to BIER OAM) had to
>> say about the state of BIER OAM work. I agree with Tony's summary that our
>> joint efforts already created the toolset of the distinctive solutions for
>> BIER OAM. We've followed draft-ietf-bier-oam-requirements
>> <https://datatracker.ietf.org/doc/draft-ietf-bier-oam-requirements/> to
>> define the comprehensive set of OAM mechanisms that support proactive and
>> on-demand failure detection and localization using both BFD and echo
>> request/reply. Also, as Tony mentioned, we have drafts on path MTU
>> discovery in the BIER environment and application of the Alternate Marking
>> method for the packet delay and packet loss measurement in a BIER domain.
>> In my opinion, the section on OAM in draft-ietf-bier-ipv6-requirements is
>> helpful. I have a question on the intention of the following wording:
>>
>> .... by specifying a new method for the same functionality.
>>
>> If there's, for example, WG draft on proactive failure detection in the
>> BIER network using p2mp BFD with unsolicited notifications, why would we
>> entertain the idea of defining a new protocol or method for the same
>> purpose? I think that the ability to use BIER OAM solutions as defined in
>> their respective drafts already accepted by the WG (and some even passed
>> WGLC) is the litmus test for any proposed method of realizing BIER in IPv6
>> network. Thus I propose the following change of Section 3.1.4
>> <https://tools.ietf.org/html/draft-ietf-bier-ipv6-requirements-09#section-3.1.4>
>> :
>>
>> OLD TEXT:
>>
>>    BIER OAM tools like [I-D.ietf-bier-ping] and [I-D.ietf-bier-pmmm-oam]
>>    should be supported, either directly using existing methods, or by
>>    specifying a new method for the same functionality.  They are likely
>>    to be needed in normal BIER deployment for diagnostics.
>>
>> NEW TEXT:
>>
>>    BIER OAM tools defined in WG document, for example,
>>
>>    [I-D.ietf-bier-ping] and [I-D.ietf-bier-pmmm-oam],
>>    must be supported as defined in the respective specifications.
>> Consistency
>>
>>    of OAM BIER tools is essential for the productive operation of BIER
>> networks.
>>
>>
>>
>>
>>
>> Regards,
>>
>> Greg
>>
>>
>>
>>
>>
>> RE:  Greg Mirsky start of BIER IPv6 OAM discussion related to the two
>> IPV6 environment solutions
>>
>>
>>
>> Hi Tianran,
>>
>> I just recently read both proposals - BIERin6 and BIERv6. Understandably,
>> I was interested in how each solution handles BIER OAM.
>>
>> draft-zhang-bier-bierin6 explains that:
>>
>>    BIER has its own OAM function, so generally the IPv6 OAM function is
>>    not needed.
>>
>> And I agree with that conclusion. BIER OAM will work because BIER header
>> is used as defined in RFC 8296, including using OAM value in the Proto
>> field.
>>
>> draft-xie-bier-ipv6-encapsulation states that:
>>
>>         How BIER-PING is supported in BIERv6
>>         encapsulation without using this Proto field is outside the
>>         scope of this document.
>>
>> That left me with many questions. Thus, from my point of view, BIERv6
>> needs to demonstrate how BIER OAM, as defined in numerous WG drafts, works
>> in BIERv6 domain. Without that, I cannot compare the two proposals fairly.
>>
>>
>>
>> Regards,
>>
>> Greg
>>
>>
>>
>>
>>
>>
>>
>> --
>>
>> <http://www.verizon.com/>
>>
>> *Gyan Mishra*
>>
>> *Network Solutions Architect *
>>
>>
>>
>> *M 301 502-1347 13101 Columbia Pike
>> <https://www.google.com/maps/search/13101+Columbia+Pike%C2%A0+%0D%0A+Silver+Spring,+MD?entry=gmail&source=g>
>> *Silver Spring, MD
>> <https://www.google.com/maps/search/13101+Columbia+Pike%C2%A0+%0D%0A+Silver+Spring,+MD?entry=gmail&source=g>
>>
>> <https://www.google.com/maps/search/13101+Columbia+Pike%C2%A0+%0D%0A+Silver+Spring,+MD?entry=gmail&source=g>
>>
>>
>>
>> --
>>
>> <http://www.verizon.com/>
>>
>> *Gyan Mishra*
>>
>> *Network Solutions Architect *
>>
>>
>>
>> *M 301 502-1347 13101 Columbia Pike
>> <https://www.google.com/maps/search/13101+Columbia+Pike%C2%A0+%0D%0A+Silver+Spring,+MD?entry=gmail&source=g>
>> *Silver Spring, MD
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>>
>> <https://www.google.com/maps/search/13101+Columbia+Pike%C2%A0+%0D%0A+Silver+Spring,+MD?entry=gmail&source=g>
>>
>>
>>
>> --

<http://www.verizon.com/>

*Gyan Mishra*

*Network Solutions A**rchitect *



*M 301 502-134713101 Columbia Pike *Silver Spring, MD