Re: [Detnet] Packet Ordering Function (draft-varga-detnet-pof-00.txt)

Greg Mirsky <gregimirsky@gmail.com> Sat, 24 April 2021 01:04 UTC

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From: Greg Mirsky <gregimirsky@gmail.com>
Date: Fri, 23 Apr 2021 18:03:52 -0700
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Subject: Re: [Detnet] Packet Ordering Function (draft-varga-detnet-pof-00.txt)
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Hi Balazs,
thank you for the well-designed mechanism of one of the key DetNet
functions.
I have a scenario and would appreciate your consideration if you think it
is a plausible one:

   - assume that POFLastSent = 100
   - a packet with seq_num = 103 is received and placed into the buffer for
   the duration of POFMaxDelay
   - next received packet has seq_num = 102. It is also moved into the
   buffer for the duration of POFMaxDelay
   - finally, before all delayed packets transmitted out of the buffer, a
   packet with seq_num = 101 is received and is forwarded right away
   - the delay timer expires on the packet with seq_num=103. It is
   forwarded and  POFLastSent = 103
   - next, the delay timer expires on the packet with seq_num=102. It, in
   turn, is forwarded and  POFLastSent = 102
   - from now, based on my understanding of the described POF algorithm,
   every packet will be delayed even if there are no re-ordered packets. For
   example, the sequence of arriving packets is as 104, 105, 106, ...

Much appreciate your opinion if the scenario, i.e., a sequence like 100,
103, 102, 101, is a realistic one.

Regards,
Greg

On Mon, Apr 19, 2021 at 10:39 PM Balázs Varga A <balazs.a.varga=
40ericsson.com@dmarc.ietf.org> wrote:

> Hi,
>
> A draft on Packet Ordering Function (POF) algorithms were uploaded.
> Comments and views are highly appreciated.
>
> Thanks
> Bala'zs (and the authors)
>
> -----Original Message-----
> From: internet-drafts@ietf.org <internet-drafts@ietf.org>
> Sent: Tuesday, April 20, 2021 7:14 AM
> To: Balázs Varga A <balazs.a.varga@ericsson.com>om>; Janos Farkas <
> Janos.Farkas@ericsson.com>gt;; Balázs Varga A <balazs.a.varga@ericsson.com>om>;
> Janos Farkas <Janos.Farkas@ericsson.com>om>; Stephan Kehrer <
> Stephan.Kehrer@belden.com>gt;; Stephan Kehrer <stephan.kehrer@belden.com>om>;
> Tobias Heer <Tobias.Heer@belden.com>om>; Tobias Heer <tobias.heer@belden.com>
> Subject: New Version Notification for draft-varga-detnet-pof-00.txt
>
>
> A new version of I-D, draft-varga-detnet-pof-00.txt has been successfully
> submitted by =?utf-8?q?Bal=C3=A1zs_Varga?= and posted to the IETF
> repository.
>
> Name:           draft-varga-detnet-pof
> Revision:       00
> Title:          Deterministic Networking (DetNet): Packet Ordering Function
> Document date:  2021-04-19
> Group:          Individual Submission
> Pages:          10
> URL:
> https://www.ietf.org/archive/id/draft-varga-detnet-pof-00.txt
> Status:         https://datatracker.ietf.org/doc/draft-varga-detnet-pof/
> Htmlized:
> https://datatracker.ietf.org/doc/html/draft-varga-detnet-pof
> Htmlized:       https://tools.ietf.org/html/draft-varga-detnet-pof-00
>
>
> Abstract:
>    Replication and Elimination functions of DetNet [RFC8655] may result
>    in out-of-order packets, which may not be acceptable for some time-
>    sensitive applications.  The Packet Ordering Function (POF) algorithm
>    described herein enables to restore the correct packet order when
>    replication and elimination functions are used in DetNet networks.
>
>
>
>
> Please note that it may take a couple of minutes from the time of
> submission until the htmlized version and diff are available at
> tools.ietf.org.
>
> The IETF Secretariat
>
>
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