Re: [tsvwg] Question about proper node behavior -ECN

[Gorry Fairhurst <[e-mail]>]

On 17/05/2023 15:57, Ingemar Johansson S wrote:
>
> Hi
>
> A very short question.. I am trying to find the proper refrenence that 
> says that nodes (routers, 5G gNB, WiFi AP...) should not remark 
> Not-ECT to any of the other 3 code points. Where do I find it
>
> Regards
> /Ingemar
>
Hi Ingemar,

A start is the statment in RFC3168 that says this in section 22:


    Prior toRFC 2474  <https://datatracker.ietf.org/doc/html/rfc2474>, routers were not permitted to modify bits in
    either the DSCP or ECN field of packets forwarded through them, and
    hence routers that comply only with RFCs prior to 2474 should have no
    effect on ECN.

Hence, if a router is not permitted to modify the field, unless it supports a spec that implements ECN.

Section 5 then states this is updated as:

The not-ECT codepoint '00' indicates a packet that is not using ECN.

I am sure someone will tell us if there is a clearer reference text somewhere else.

Best wishes,
Gorry