Re: [sfc] I-D Action: draft-ietf-sfc-nsh-ecn-support-06.txt

While such a facility (to inform about packet changes) has 
understandable value, I tend to doubt the likelihood of it being used. 
It seeems an unlikely upgrade for a SF builder to bother implementing, 
since it is likely to be significant effort.  And existing SF (including 
all those behind proxies) will not support it.

Yours,
Joel

On 9/13/2021 4:56 PM, Donald Eastlake wrote:
> This revision has minor wording improvements.
> 
> To my mind there is one substantial issue with this draft: What to do
> about SFs that add or remove packets from a flow or lengthen or
> shorten such packets. If this is ignored, the document is much less
> useful for such flows. The simplest solution seems to be that such SFs
> should optionally signal forward in separate packets the changes they
> have made, of this sort, to flows. I plan to look into adding such a
> facility.
> 
> Thanks,
> Donald
> ===============================
>   Donald E. Eastlake 3rd   +1-508-333-2270 (cell)
>   2386 Panoramic Circle, Apopka, FL 32703 USA
>   d3e3e3@gmail.com
> 
> On Mon, Sep 13, 2021 at 4:06 PM <internet-drafts@ietf.org> wrote:
>>
>>
>> A New Internet-Draft is available from the on-line Internet-Drafts directories.
>> This draft is a work item of the Service Function Chaining WG of the IETF.
>>
>>          Title           : Explicit Congestion Notification (ECN) and Congestion Feedback Using the Network Service Header (NSH) and IPFIX
>>          Authors         : Donald E. Eastlake
>>                            Bob Briscoe
>>                            Yizhou Li
>>                            Andrew G. Malis
>>                            Xinpeng Wei
>>          Filename        : draft-ietf-sfc-nsh-ecn-support-06.txt
>>          Pages           : 33
>>          Date            : 2021-09-13
>>
>> Abstract:
>>     Explicit congestion notification (ECN) allows a forwarding element to
>>     notify downstream devices of the onset of congestion without having
>>     to drop packets. Coupled with a means to feed information about
>>     congestion back to upstream nodes, this can improve network
>>     efficiency through better congestion control, frequently without
>>     packet drops. This document specifies ECN and congestion feedback
>>     support within a Service Function Chaining (SFC) architecture domain
>>     through use of the Network Service Header (NSH, RFC 8300) and IP Flow
>>     Information Export (IPFIX, RFC 7011).
>>
>>
>>
>> The IETF datatracker status page for this draft is:
>> https://datatracker.ietf.org/doc/draft-ietf-sfc-nsh-ecn-support/
>>
>> There is also an htmlized version available at:
>> https://datatracker.ietf.org/doc/html/draft-ietf-sfc-nsh-ecn-support-06
>>
>> A diff from the previous version is available at:
>> https://www.ietf.org/rfcdiff?url2=draft-ietf-sfc-nsh-ecn-support-06
>>
>>
>> Internet-Drafts are also available by anonymous FTP at:
>> ftp://ftp.ietf.org/internet-drafts/
>>
>>
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> 
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