[ippm] Re: Adoption call for draft-whimir-ippm-cos-ecn

[Marcus Ihlar <[e-mail]>]

Thanks for your input, Sebastian,
Do you believe that the current version of the specification is good enough for adoption and that your proposed improvements can be handled as part of the normal WG process?

BR
Marcus

-----Original Message-----
From: Sebastian Moeller <moeller0=[e-mail]>
Sent: Wednesday, 26 November 2025 10:09
To: Will Hawkins <[e-mail]>
Cc: [e-mail]
Subject: [ippm] Re: Adoption call for draft-whimir-ippm-cos-ecn

Dear List,

I am not convinced that the proposed structure of the actual data is as good as we can make it:
I would propose a simpler scheme

Intended forward DSCP: 6 bit
Intended forward ECN: 2 bit

# this should be empty in forward packets Received forward DSCP: 6 bit Received forward ECN: 2 bit

Intended return DSCP: 6bit
Intended return ECN: 2bit

# this should be empty in forward packets Applied return DSCP: 6bit Applied return ECN: 2bit


The advantages are:
1) same size
2) no padding
3) the initial sender needs to keep less state
4) captured packets contain sufficient information for analysis without having to know sender internal state
5) data ordering (DSCP followed by ECN) matches the order of the bitfields in the actual IP headers, so these could be filled in bulk.

The disadvantages are:
1) no reserve bits, but I argue these are not all that helpful as they invite shoehorning...
2) ambiguity about whether a packet is on the way to or from the reflector and hence whether Received and Applied values are meaningful


And I would request two new STAMP TLV Types values:

CoSv2 request
CoSv2 response

to remove the ambiquity whether Received and Applied are truly zero or simply not yet filled.

Seems considerably cleaner than trying to shoehorn the new values into the existing format and there seem to be ample space for new STAMP TLV Types


Regards
        Sebastian




> On 25. Nov 2025, at 03:29, Will Hawkins <[e-mail]> wrote:
>
> I support!!
>
> On Mon, Nov 24, 2025 at 8:14 PM <[e-mail]> wrote:
>>
>> Hello all,
>>
>> The draft provides an effective approach for validating and monitoring L4S deployments. I support to progress it to the next stage.
>>
>>
>> Best regards,
>>
>> Xueyan
>>
>>
>> Original
>> From: MarcusIhlar <marcus.ihlar=[e-mail]>
>> To: [e-mail] <[e-mail]>;
>> Date: 2025年11月25日 05:46
>> Subject: [ippm] Adoption call for draft-whimir-ippm-cos-ecn
>> _______________________________________________
>> ippm mailing list -- [e-mail]
>> To unsubscribe send an email to [e-mail]
>>
>> Hello IPPM,
>>
>> This email starts an adoption call for “Update of the Simple Two-way Active Measurement Protocol Class-of-Service Extension – ECN” (draft-whimir-ippm-cos-ecn).
>>
>>
>>
>> You can find the draft here:
>>
>> https://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdat
>> atracker.ietf.org%2Fdoc%2Fdraft-whimir-ippm-stamp-cos-ecn%2F&data=05%
>> 7C02%7Cmarcus.ihlar%40ericsson.com%7C8ac2f47882de47314f3b08de2ccb7f7a
>> %7C92e84cebfbfd47abbe52080c6b87953f%7C0%7C0%7C638997449693811401%7CUn
>> known%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiO
>> iJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=9MnYOC
>> L%2BdqTVd%2FbImzTDH4AM4GqTfGevgeiSkm0L4kA%3D&reserved=0
>>
>> https://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww
>> .ietf.org%2Farchive%2Fid%2Fdraft-whimir-ippm-stamp-cos-ecn-01.html&da
>> ta=05%7C02%7Cmarcus.ihlar%40ericsson.com%7C8ac2f47882de47314f3b08de2c
>> cb7f7a%7C92e84cebfbfd47abbe52080c6b87953f%7C0%7C0%7C63899744969385370
>> 3%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCI
>> sIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=
>> mVGxBh0WGBCl29%2BsdRYnkVXeAr5kibwY5wC%2FLMcWBis%3D&reserved=0
>>
>>
>>
>> Please review the draft and respond to this email to indicate if you think IPPM should adopt this document as a working group item.
>>
>>
>>
>> This call will last for 3 weeks. Please reply by Monday, December 15.
>>
>>
>>
>> Best Regards,
>>
>> Marcus & Thomas
>>
>>
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>
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