[Last-Call] Re: [Lsr] Re: RtgDir Last Call Review: draft-ietf-lsr-multi-tlv-06

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Aijun Wang <wangaijun@xxxxxxxxxxxxxxx> writes:

Hi, Robert:

Fragments and Glue procedures is one normal, mature  process for any
slicing application. We needn’t another document to standardize it
again.

The knob for the segmentation is the information “what concerns a
key”, which is what you mentioned should be in one wiki like online
form.

If the LSR WG can formalize such “online form”, and this document
refer to it for the future implementation and interoperability
guarantee, then I can support its forwarding.

BUT, it seems impossible to define explicitly such “online form”.

And to Chris: if you think “what constitutes a key” is one well-known
knob for vendors, why the document illustrate explicitly such
information for TLV 22 and TLV 135?

And how can you assure different vendors will use the same
information for “what constitutes a key” for each IS-IS code point?

Aijun,

You have asked this many times and been answered repeatedly; however, I will answer it again, if only to make it clear to the folks reviewing the appeal.

Please stop thinking about Multi-TLV for a minute.

How does IS-IS tell one neighbor TLV (or whatever) from another -- in regular deployed IS-IS?

That is the "key" data.

The "key" data *has* to already be agreed upon by all implementations or regular IS-IS would not function -- it would literally not function. There is nothing new to define.

Thanks,
Chris.


It’s better to answer such question clearly, reasonably than to
declare in rush that document reaches the WG consensus.


Aijun Wang
China Telecom


    On Nov 12, 2024, at 08:00, Robert Raszuk <robert@xxxxxxxxxx>
    wrote:


    Hi Aijun,

    Let's make sure that my observation in respect to key elements
    clarification for each TLV does not equal to the request to
    "ABANDON" this useful document.

    I do find the ability to fragment and glue TLVs as a useful
    protocol extension. What should be sent in each fragment perhaps
    is obvious to familgia of long time ISIS developers .. so my only
    hint was to simply publish this in some online form.

    Rgs,
    Robert


    On Tue, Nov 12, 2024 at 12:45 AM Aijun Wang <
    wangaijun@xxxxxxxxxxxxxxx> wrote:

        Hi, Robert and Mach:

        Thanks for your comments on this document.
        It reveals clearly the issues existing within the documents.

        The Chairs declare repeatedly this document reached WG
        consensus, apparently it DOESN’T.

        I have submitted the appeal to IESG.
        Wish more experts to stand out to ABANDON this error prone,
        pitfall solution being published under the name of LSR, or
        IETF.

        Aijun Wang
        China Telecom


            On Nov 12, 2024, at 06:55, Robert Raszuk <
            robert@xxxxxxxxxx> wrote:


            Les,

            >  Link identifiers are indeed sub-TLVs.
            >  That does not disqualify them from being part of “key”
            information.

            Oh, it was not clear from the draft. Perhaps you can add
            this detail in the next rev.

            - - -

            If you have multiple parallel links today they will all
            be listed in the sub-TLVs - so they are ok spec wise
            today.

            I am not sure however - assuming you do not include
            "Example" in section 4.1 that everyone would be adding
            them to each TLV fragment.

            // But then we have hackathons and interop venus where
            interop bugs can be quickly found and fixed
            // if this is how it should all work out.

            That is why I do believe a sort of dictionary would be
            nice to have in either a normative spec or reference to
            such a document or even as a simple wiki page :).

            Best,
            Robert


            On Mon, Nov 11, 2024 at 11:39 PM Les Ginsberg (ginsberg)
            <ginsberg@xxxxxxxxx> wrote:


                Robert –



                Link identifiers are indeed sub-TLVs.

                That does not disqualify them from being part of
                “key” information.



                If I have multiple parallel links between two
                routers, this is how the links are uniquely
                identified. Such information is essential to
                correctly identify the link attribute information
                which in turn is essential for applications such as
                RSVP-TE, SR=TE, and flex-algo to operate correctly.



                If you think this is underspecified, I presume you
                think it is not possible for these applications to
                work correctly today – which obviously is not the
                case.



                    Les



                From: Robert Raszuk <robert@xxxxxxxxxx>
                Sent: Monday, November 11, 2024 2:16 PM
                To: Les Ginsberg (ginsberg) <ginsberg@xxxxxxxxx>
                Cc: Acee Lindem <acee.ietf@xxxxxxxxx>; Christian
                Hopps <chopps@xxxxxxxxxx>; Mach Chen <mach.chen=
                40huawei.com@xxxxxxxxxxxxxx>; Routing ADs <
                rtg-ads@xxxxxxxx>; rtg-dir@xxxxxxxx;
                draft-ietf-lsr-multi-tlv.all@xxxxxxxx; lsr <
                lsr@xxxxxxxx>; last-call <last-call@xxxxxxxx>
                Subject: Re: [Lsr] RtgDir Last Call Review:
                draft-ietf-lsr-multi-tlv-06



                Les,



                    I note that in all of these emails expressing
                    concern no one has provided a single example



                RFC5305 defines Extended IS Reachability TLV as:



                   The proposed extended IS reachability TLV contains
                a new data
                   structure, consisting of:

                      7 octets of system ID and pseudonode number
                      3 octets of default metric
                      1 octet of length of sub-TLVs



                Now your draft makes an impression that there are
                also at the TLV level itself optional link
                identifiers.



                4.1.  Example: Extended IS Reachability

                   As an example, consider the Extended IS
                Reachability TLV (type 22).
                   A neighbor in this TLV is specified by:

                   *  7 octets of system ID and pseudonode number

                   *  3 octets of default metric

                   *  Optionally one or more of the following link
                identifiers:



                      -  IPv4 interface address and IPv4 neighbor
                address as specified
                         in [RFC5305]

                      -  IPv6 interface address and IPv6 neighbor
                address as specified
                         in [RFC6119]

                      -  Link Local/Remote Identifiers as specified
                in [RFC5307]





                Can you point to the text in RFC5305 where such IPv4
                link identifier is defined ?



                I can only find them to be defined as part of
                sub-TLVs.



                Also I do not see them as LSDB keys in FRR ISIS code
                ...

                Ref: https://github.com/FRRouting/frr/blob/master/
                isisd/isisd.c



                Thx,

                R.



                    From: Acee Lindem <acee.ietf@xxxxxxxxx>
                    Sent: Monday, November 11, 2024 1:42 PM
                    To: Robert Raszuk <robert@xxxxxxxxxx>
                    Cc: Christian Hopps <chopps@xxxxxxxxxx>; Mach
                    Chen <mach.chen=40huawei.com@xxxxxxxxxxxxxx>;
                    Routing ADs <rtg-ads@xxxxxxxx>; rtg-dir@xxxxxxxx;
                    draft-ietf-lsr-multi-tlv.all@xxxxxxxx; lsr <
                    lsr@xxxxxxxx>; last-call <last-call@xxxxxxxx>
                    Subject: Re: [Lsr] RtgDir Last Call Review:
                    draft-ietf-lsr-multi-tlv-06



                    Speaking as WG member:



                        On Nov 11, 2024, at 15:21, Robert Raszuk <
                        robert@xxxxxxxxxx> wrote:



                        Dear Christian,



                        Thank you for your answer. I remain educated
                        that LSR WG born RFCs are only for those who
                        implement protocol and have years of
                        experience in doing so.



                        I was obviously wrong thinking RFCs are
                        designed to also help operators to run and
                        troubleshoot network problems. Or maybe say
                        wireshark or tcpdump developers to properly
                        decode stuff which shows up on the wire ...



                        And if this is so obvious, what is the
                        problem for someone with such experience to
                        sit down and write down a BCP
                        dict listing what in his opinions should be
                        used as a key for each TLV listed in section
                        8.2 ? If done weeks before we would not have
                        such discussion.



                    If done correctly, this document would be
                    welcomed. However, it should be a gating factor
                    on specification of IS-IS MP-TLVs.



                    Thanks,

                    Acee











                        Kind regards,

                        Robert



                        On Mon, Nov 11, 2024 at 9:05 PM Christian
                        Hopps <chopps@xxxxxxxxxx> wrote:

                            As was pointed out on the list, anyone
                            implementing IS-IS knows exactly what a
                            key is b/c it’s literally the value they
                            use to differentiate TLVs from one
                            another — IOW *A KEY VALUE*. You don’t
                            consider 2 neighbor TLVs to be different
                            neighbors (and allocate a neighbor
                            structure to store in your DB of
                            neighbors) based on the TLV metric value.
                            This really is obvious when people stop
                            treating the discussion as some
                            abstraction which is again what people
                            keep pointing out.

                            Thanks,
                            Chris.

                            > On Nov 11, 2024, at 08:13, Robert
                            Raszuk <robert@xxxxxxxxxx> wrote:
                            >
                            > Hi Chris,
                            >
                            > > The WG explicitly decided it was
                            inappropriate to have this document
                            re-define
                            > > every "key" for every possible TLV as
                            these "key" values are already defined
                            > > by the documents that define the TLV;
                            >
                            > I have followed this discussion on the
                            list.
                            >
                            > It seems to be as a side observer that
                            folks questioning the WGLC and
                            progressing the document do have a valid
                            point.
                            >
                            > The document by its title and by
                            section 8.2 creates an impression that it
                            is a universal spec for all TLVs in
                            respect how to implement MP-TLVs for
                            them.
                            >
                            > Yet we clearly see from examples
                            provided in sections 4.1 and 4.2 that
                            what constitutes a "key" is TLV dependent
                            and it is really cherry picked out of the
                            number of values carried in a TLV.
                            >
                            > An example from section 4.1:  In TLV 22
                            - 3 octets of def metric is skipped and
                            not considered as a key
                            >
                            > An example from section 4.2: In TLV 135
                            -  4 octets of metric information and two
                            bits of control information octet are
                            skipped and not considered as a key
                            >
                            > So if an implementer takes this
                            document and attempts to write up MP-TLV
                            how is he going to figure out which
                            values for all other listed TLVs in 8.2
                            constitute a key and which not ?
                            >
                            > IMO this document can proceed however
                            only in respect to TLV 22 and TLV 135 and
                            both its title and content should reflect
                            this.
                            >
                            > Cheers,
                            > Robert
                            >
                            > On Mon, Nov 11, 2024 at 1:27 PM
                            Christian Hopps <chopps@xxxxxxxxxx>
                            wrote:
                            >
                            > Mach Chen <mach.chen=
                            40huawei.com@xxxxxxxxxxxxxx> writes:
                            >
                            > > Hello,
                            > >
                            > > I have been selected as the Routing
                            Directorate reviewer for this draft. The
                            > > Routing Directorate seeks to review
                            all routing or routing-related drafts as
                            > > they pass through IETF last call and
                            IESG review, and sometimes on special
                            > > request. The purpose of the review is
                            to provide assistance to the Routing ADs.
                            > > For more information about the
                            Routing Directorate, please
                            > > see https://wiki.ietf.org/en/group/
                            rtg/RtgDir
                            > >
                            > > Although these comments are primarily
                            for the use of the Routing ADs, it would
                            > > be helpful if you could consider them
                            along with any other IETF Last Call
                            > > comments that you receive, and strive
                            to resolve them through discussion or by
                            > > updating the draft.
                            > >
                            > > Document: https://
                            datatracker.ietf.org/doc/
                            draft-ietf-lsr-multi-tlv-06
                            > > Reviewer: Mach Chen
                            > > Review Date: 2024-11-11
                            > > IETF LC End Date:
                            > > Intended Status: Standards Track
                            > >
                            > > Summary:
                            > > • I have some major and minor
                            concerns about this document that I think
                            should be resolved before publication.
                            > >
                            > > Comments:
                            > > • The document is well written and
                            easy to read it.
                            > >
                            > > Major Issues:
                            > > 1. The definitions of the 'Key' for
                            TLVs and sub-TLVs vary, and this document
                            > > does not specify the Key for each
                            MP-TLV. Therefore, it may result in
                            > > interoperability issues if
                            implementations use different information
                            to
                            > > construct the 'Key.' Given Section
                            8.2 listed all existing applicable
                            MP-TLVs,
                            > > it's essential to specify the Key for
                            each of those MP-TLVs, either within this
                            > > document or in a separate document to
                            which this document should provide a
                            > > normative reference.
                            >
                            > Hi Mach,
                            >
                            > I'm curious if you also followed along
                            on the extensive discussions on this
                            exact issue on the LSR list or not?
                            >
                            > Understanding your exposure to this
                            would help with how to address any
                            remaining confusion about this directly
                            in the draft.
                            >
                            > The WG explicitly decided it was
                            inappropriate to have this document
                            re-define every "key" for every possible
                            TLV as these "key" values are already
                            defined by the documents that define the
                            TLV; however, documenting that choice and
                            the reasoning better may still be
                            necessary.
                            >
                            > So my question is this: were you
                            following along with this discussion in
                            the LSR WG and find yourself disagreeing
                            with the WG decision, or is this entire
                            topic new to you?
                            >
                            > Thanks,
                            > Chris.
                            >
                            >
                            > >
                            > > Minor Issues:
                            > > 1. The MP-TLV Capability
                            Advertisement is defined as a node-based
                            capability
                            > > rather than on a per-codepoint basis,
                            which limits its usefulness. In some
                            > > cases, it may even be misleading if
                            operators just rely on this capability to
                            > > assume MP-TLV support. Therefore, it
                            would be preferable to either remove this
                            > > capability advertisement or redefine
                            it to operate on a per-codepoint basis.
                            > >
                            > > Best regards,
                            > > Mach
                            >
                            >
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