Hello Magnus,

AFAIK, linux, Windows, Mac - all support reading ECN bits on received packets. 
Could you let me know which OS doesn’t support this?

Vidhi

> On Feb 28, 2023, at 4:31 AM, Magnus Westerlund 
> <[email protected]> wrote:
> 
> Hi,
>  
> I support Martin’s proposed way forward with this errata. The reality here is 
> that we in no way could force ECN reporting due to the state of difficulties 
> to access the ECN bits on received packets on some OS, and from user space 
> QUIC implementations so that was never the intention. So I think this is only 
> an editorial issue of not appear conflicting in the text.
>  
> Cheers
>  
> Magnus
>  
> From: QUIC <[email protected]> on behalf of Martin Thomson 
> <[email protected]>
> Date: Tuesday, 28 February 2023 at 01:23
> To: [email protected] <[email protected]>
> Subject: Re: [Technical Errata Reported] RFC9000 (7374)
> 
> This change would not hurt if we were actively editing, but I don't think it 
> is necessary.  Not implementing ECN is a great way to ensure that ECN 
> markings are unavailable to an endpoint.  Bob is right that we create 
> confusion by making a distinction in one place and not the other, but it 
> doesn't really change the meaning.
> 
> I suggest that we reassign this to Editorial and mark it Hold for Document 
> Update.
> 
> On Tue, Feb 28, 2023, at 10:04, RFC Errata System wrote:
> > The following errata report has been submitted for RFC9000,
> > "QUIC: A UDP-Based Multiplexed and Secure Transport".
> >
> > --------------------------------------
> > You may review the report below and at:
> > https://www.rfc-editor.org/errata/eid7374
> >
> > --------------------------------------
> > Type: Technical
> > Reported by: Bob Briscoe <[email protected]>
> >
> > Section: 13.4.1
> >
> > Original Text
> > -------------
> >                                                                If an
> >    endpoint does not implement ECN support or does not have access to
> >    received ECN fields, it does not report ECN counts for packets it
> >    receives.
> >
> >    Even if an endpoint does not set an ECT field in packets it sends,
> >    the endpoint MUST provide feedback about ECN markings it receives, if
> >    these are accessible.  
> >
> > Corrected Text
> > --------------
> >                                                                If an
> >    endpoint does not have access to
> >    received ECN fields, it does not report ECN counts for packets it
> >    receives.
> >
> >    Even if an endpoint does not set an ECT field in packets it sends,
> >    the endpoint MUST provide feedback about ECN markings it receives, if
> >    these are accessible.  
> >
> > Notes
> > -----
> > In the second sentence, the only allowed exception to "MUST provide 
> > feedback about received ECN markings" is inaccessibility. The first 
> > sentence contradicts this by allowing two exceptions: inaccessibility 
> > and just "not implementing ECN support". 
> >
> > If "not implementing ECN support" was really intended to be an allowed 
> > exception, the capitalized "MUST" would have been pointless.
> >
> > Therefore it is proposed that the words "does not implement ECN support 
> > or " are deleted from the first paragraph.
> >
> > Instructions:
> > -------------
> > This erratum is currently posted as "Reported". If necessary, please
> > use "Reply All" to discuss whether it should be verified or
> > rejected. When a decision is reached, the verifying party  
> > can log in to change the status and edit the report, if necessary. 
> >
> > --------------------------------------
> > RFC9000 (draft-ietf-quic-transport-34)
> > --------------------------------------
> > Title               : QUIC: A UDP-Based Multiplexed and Secure Transport
> > Publication Date    : May 2021
> > Author(s)           : J. Iyengar, Ed., M. Thomson, Ed.
> > Category            : PROPOSED STANDARD
> > Source              : QUIC
> > Area                : Transport
> > Stream              : IETF
> > Verifying Party     : IESG

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