Re: [Bier] BIERv6 and BIERin6 OAM support discussion

Gyan Mishra <> Thu, 26 November 2020 05:49 UTC

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From: Gyan Mishra <>
Date: Thu, 26 Nov 2020 00:49:10 -0500
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To: BIER WG <>, Greg Mirsky <>, Greg Shepherd <>, Gyan Mishra <>, Michael McBride <>, Tianran Zhou <>, Tony Przygienda <>, Xiejingrong <>
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Subject: Re: [Bier] BIERv6 and BIERin6 OAM support discussion
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With BIERv6 the Bier header encoded in DOH, as it is encoded as long as we
include the 2 bit OAM field for PNPM in the DOH encoding, is it possible
that OAM could work with BIERv6?

Kind Regards

On Thu, Nov 26, 2020 at 12:37 AM Gyan Mishra <> wrote:

> 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 <>
> 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.
>> -- 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
>> <> 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
>> <>
>> :
>>    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.
>>    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
>> --
>> <>
>> *Gyan Mishra*
>> *Network Solutions A**rchitect *
>> *M 301 502-134713101 Columbia Pike *Silver Spring, MD
>> --
> <>
> *Gyan Mishra*
> *Network Solutions A**rchitect *
> *M 301 502-134713101 Columbia Pike *Silver Spring, MD
> --


*Gyan Mishra*

*Network Solutions A**rchitect *

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