Hi Chris,
You are 100% correct that today all specifications already define a set of values which are necessary to recognize TLVs to be coming from the same originator (originator can be a node_id or node_id+link_id etc ...).
What seems to be the crux of the matter here is that MP-TLV spec recommends with normative MUST that a *subset* of those values (aka "keys") should be used when fragmenting TLV into chunks and attach to each one of them. It is this lack of definition on what is that *subset* which seems to be missing here.
Intuitively, and I think this is highlighted in your and Les's responses that *subset* is what makes the TLV unique ... so values like metric, down/up bits etc ... would not be part of such *subsets*. The issue is that this is nowhere defined.
So perhaps instead of asking to create a live document where such subsets are explicitly enumerated for each TLV (which still may be useful and can be done in no time as each IETF WG already have a wiki page) - for this current topic maybe just define in the MP-TLV doc this *subset* as unique set of elements used for identification and we will be done. (Even if for folks working on ISIS for decades this is soooo obvious :).
Thx,
Robert
On Tue, Nov 12, 2024 at 10:29 AM Christian Hopps <chopps@xxxxxxxxxx> wrote:
Aijun,
Key values are defined in existing RFCs, the actual use of the word "KEY" is not necessary to understand what the key data is. Sadly, this has had to be repeated over and over and over in this discussion to no affect.
While reading the following text, please just consider regular IS-IS (i.e., the set of existing standards)
If the key data wasn't already defined in the existing RFCs then each router would store exactly 0 or 1 of each TLV code point. You would have 0 or 1 neighbor TLV, you would have 0 or 1 IP reachable prefix, etc.
And IS-IS would be utterly broken as a protocol.
So then ask yourself, how does IS-IS tell these TLVs apart? How do we support more than 1 neighbor already? Because we have *key* data in each TLV to identify each neighbor as different from the other!
If the key data wasn't already defined and understood you literally couldn't have more than 1 of each of these TLVs in exiting IS-IS.
[rhetorical] Do you believe that IS-IS currently only supports 1 neighbor, only 1 IPv4 prefix, only 1 IPv6 prefix?
Nothing new is being introduced, no new "key"s are being defined, no new "keys" need to be defined. There can be no confusion on what the key data is or IS-IS would not work at all.
Thanks,
Chris.
[as wg-member]
"Aijun Wang" <wangaijun@xxxxxxxxxxxxxxx> writes:
> Hi, Chris:
>
> I recommended you read carefully the arguments from Robert https://mailarchive.ietf.org/arch/msg/lsr/g6r1zwMfcmOPUoKMNYOMidvyqeA/
>
> And also to Les's statement: " But defining encodings that are already fully specified in existing RFCs is not in scope."--------we are arguing where in existing RFC gives the information "what constitute a key"?
> WHERE? We can limit only to TLV 22 and TLV135, as the examples in your document.
>
>
> For your conveniences, I copied the original part(there is no any change) as the below:
>
> ============================Quote Start(Mail from Robert, Nov. 11, 2024)=========================================================
> 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.
> ========================= Quote End(Mail from Robert, Nov. 11, 2024)=============================================================
>
>
>
>
> -----邮件原件-----
> 发件人: forwardingalgorithm@xxxxxxxx [mailto:forwardingalgorithm@xxxxxxxx] 代表 Christian Hopps
> 发送时间: 2024年11月12日 14:08
> 收件人: Aijun Wang <wangaijun@xxxxxxxxxxxxxxx>
> 抄送: Robert Raszuk <robert@xxxxxxxxxx>; Les Ginsberg (ginsberg) <ginsberg@xxxxxxxxx>; 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>
> 主题: [Lsr] Re: RtgDir Last Call Review: draft-ietf-lsr-multi-tlv-06
>
>
> 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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>>
>>
>>
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