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

Hi Martin,
thank you for your kind consideration of this work and your thoughtful
comments. Please find my notes below under the GIM>> tag.

Regards,
Greg

On Thu, Sep 21, 2023 at 1:45 PM 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.
>
GIM>> Thank you, Martin.

>
> 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.
>
GIM>> I agree that perhaps not all the corner cases have been sufficiently
analyzed and described in this version. I hope that if the fundamental
mechanism is seen as plausible, then handling the error cases can be
resolved by pulling together the expertise of the WG.

>
> 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.
>
GIM>> Will work on update to clarify that.

>
> 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?
>
GIM>> That is an option, than can be used based on the mode selected by an
operator. The goal of designing HTS is to provide an efficient mechanism
for collecting telemetry information generated by an on-path OAM protocol,
e.g., IOAM. The ability of a transit node to generate an additional
followup packet is intended to assist in collecting as much as possible of
available in the network telemetry information in case when the
ingress-originated packet is lost.

>
> 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.
>
GIM>> Thank you for pointing that out. We'll discuss and enhance the
mechanism with the followup packet sequencing mechanism.

>
> 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?
>
GIM>> It is assumed that the characteristic information that identifies the
flow monitored by the op-path OAM and the trigger packet also used to
identify the associated with it followup packets. I agree that a followup
packet may be misdirected. Will work on the detection mechanism in the
future versions.

>
> This is not very important, but I find "hybrid two-step" to be a
> nondescriptive name, and might prefer something like "IOAM Followon".
>
GIM>> While IOAM is an important on-path OAM mechanism, we believe that
other on-path mechanisms, e.g., the Alternate Marking method, can benefit
from combination with HTS.

>
> 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
>> _______________________________________________
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>> ippm@ietf.org
>> https://www.ietf.org/mailman/listinfo/ippm
>>
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