Re: [ippm] Call for adoption for draft-mirsky-ippm-hybrid-two-step

Hi Bjorn,
thank you for your commentsv and thought-inspiring questions. Please find
my notes inline below under the GIM>> tag.

Regards,
Greg

On Fri, Sep 22, 2023 at 6:52 AM Bjørn Ivar Teigen <bjorn@domos.no> wrote:

> IPPM WG,
>
> I support adopting this document.
> I do think it is a bit challenging to understand the motivations for the
> mechanism, but that can probably be easily fixed by adding some clarifying
> text and/or diagrams.
>
GIM>> Thank you for supporting this work; much appreciated. We are working
on extending and clarifying the text to demonstrate motivations and goals
set for HTS.

>
> Here are my comments on the draft:
>
>    - Is one of the purposes of the two-packet approach to separate
>    measurements from different domains from each other? (I.e. by having one
>    ingress and egress node for each domain, but one trigger packet that
>    triggers measurements at all of the domains) If so, perhaps adding a
>    diagram will make that more clear.
>
> GIM>> Thank you for your suggestion. This is an interesting scenario.
We'll add it with text and an ASCII-art diagram.

>
>    - Is the purpose of the trigger packet to signal each intermediate
>    node to take a measurement immediately? The list of things for the
>    intermediate node to do upon receiving a trigger packet does not include
>    taking a measurement. Is that an oversight?
>
> GIM>> A great question, thanks! Thinking about on-path telemetry
measurements and HTS, as an example of telemetry information collection, in
some cases, we might distinguish the trigger of measurement from the
trigger of exporting telemetry information. Let's discuss that further.

>
>    - If I understand correctly there can only be one trigger packet
>    active at a time. That limits the measurement rate to one measurement per
>    round-trip. Is that correct? If so, this limitation should be more clearly
>    stated.
>
> GIM>> I think that the answer could be defined by the answer to your
question above ;) Let's look at them together.

> Best regards,
> Bjørn Ivar Teigen
>
> On Fri, 22 Sept 2023 at 12:54, Martin Duke <martin.h.duke@gmail.com>
> wrote:
>
>> I agree that this type of work is in-charter.
>>
>> I can't speak to whether this answers a big need or anyone would deploy
>> it, but I don't see a fundamental problem with adoption, assuming there are
>> satisfactory answers to the questions below.
>>
>> I can see how something like this could go haywire, with followon packets
>> getting misrouted, reordered, or lost, and wonder if we have enough
>> experience with it to be a standard, or if we should instead aim for
>> experimental.
>>
>> Some more minor comments:
>>
>> I found the motivation in the introduction to be a bit hard to
>> understand, and the abstract could use a sentence or two explaining what
>> this protocol specifically does.
>>
>> IIUC since the last major presentation @IETF 113, the model seems to have
>> evolved from each intermediate node generating its own followon packet,
>> instead the ingress node generates one and each intermediate node appends
>> to the followup. I hope that's right?
>>
>> It's also disturbing to me that there doesn't seem to be strong
>> wire-image synchronization between the trigger packet and followon packet
>> via a common sequence number or something else. This could lead to
>> confusion at the egress.
>>
>> What assurances are there that the followon packet followed the same path
>> from ingress to egress as the trigger packet? What are the consequences of
>> this not happening and remaining undetected?
>>
>> This is not very important, but I find "hybrid two-step" to be a
>> nondescriptive name, and might prefer something like "IOAM Followon".
>>
>> Martin
>>
>>
>> On Tue, Sep 19, 2023 at 11:28 AM Haoyu Song <haoyu.song@futurewei.com>
>> wrote:
>>
>>> IPPM WG,
>>>
>>>
>>>
>>> As a coauthor, I support the adoption of the draft as the WG document.
>>> The hybrid approach complements with the other IOAM approaches well and has
>>> its own merits.  Thanks!
>>>
>>>
>>>
>>> Best,
>>>
>>> Haoyu
>>>
>>>
>>>
>>> *From:* ippm <ippm-bounces@ietf.org> *On Behalf Of * Tommy Pauly
>>> *Sent:* Wednesday, September 13, 2023 9:22 AM
>>> *To:* IETF IPPM WG <ippm@ietf.org>
>>> *Subject:* [ippm] Call for adoption for
>>> draft-mirsky-ippm-hybrid-two-step
>>>
>>>
>>>
>>> Hello IPPM,
>>>
>>>
>>>
>>> This email starts a call for adoption for
>>> draft-mirsky-ippm-hybrid-two-step. This draft has been around for a while
>>> and discussed several times on list and in WG meetings.
>>>
>>>
>>>
>>> https://datatracker.ietf.org/doc/draft-mirsky-ippm-hybrid-two-step/
>>>
>>> https://www.ietf.org/archive/id/draft-mirsky-ippm-hybrid-two-step-15.html
>>>
>>>
>>>
>>> Please review the document and email the list with your comments, and if
>>> you think IPPM should adopt this work.
>>>
>>>
>>>
>>> This call for adoption will last three weeks and end on *October 4th*.
>>>
>>>
>>>
>>> Best,
>>>
>>> Tommy
>>> _______________________________________________
>>> ippm mailing list
>>> ippm@ietf.org
>>> https://www.ietf.org/mailman/listinfo/ippm
>>>
>> _______________________________________________
>> ippm mailing list
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>> https://www.ietf.org/mailman/listinfo/ippm
>>
>
>
> --
> Bjørn Ivar Teigen, Ph.D.
> Head of Research
> +47 47335952 | bjorn@domos.ai | www.domos.ai
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