Re: [IPFIX] draft-ietf-opsawg-ipfix-fixes: tcpOptions/ipv4Options bit mappings

[[e-mail]]

Hi Paul, all,

I digged into ipfix archives to see the discussion that happened around these errata and when scrolling I found this message:
https://mailarchive.ietf.org/arch/msg/ipfix/v9ywSgTeYzataQnhMG-x7SxLo0U/ but no follow-up.

This confirms my initial assessment that a fix is needed.

Cheers,
Med

De : BOUCADAIR Mohamed INNOV/NET
Envoyé : mardi 19 septembre 2023 15:02
À : 'Aitken, Paul' <[e-mail]>; opsawg <[e-mail]>; Benoit Claise <[e-mail]>
Objet : RE: draft-ietf-opsawg-ipfix-fixes: tcpOptions/ipv4Options bit mappings

Hi Paul,

Yes, that's what I was referring to in my previous messages when I said "FWIW, (1) is what was followed in RFC5102 but changed since then by errata.".

I'm having trouble with that errata as I don't understand why the reversal was only made at the octet level and not the full IE + how to link that with "Option number X is mapped to bit X".

Thank you.

Cheers,
Med

De : Aitken, Paul <[e-mail]<mailto:[e-mail]>>
Envoyé : mardi 19 septembre 2023 12:13
À : BOUCADAIR Mohamed INNOV/NET <[e-mail]<mailto:[e-mail]>>; opsawg <[e-mail]<mailto:[e-mail]>>; Benoit Claise <[e-mail]<mailto:[e-mail]>>
Objet : Re: draft-ietf-opsawg-ipfix-fixes: tcpOptions/ipv4Options bit mappings

Med, this figure originally appeared in section 5.8.8 of draft-ietf-ipfix-info-13, -14, and RFC 5102 with the bits in this order:

              0     1     2     3     4     5     6     7

          +-----+-----+-----+-----+-----+-----+-----+-----+

          |   0 |   1 |   2 |   3 |   4 |   5 |   6 |   7 |  ...

          +-----+-----+-----+-----+-----+-----+-----+-----+

The bits were reversed by this errata: https://www.rfc-editor.org/errata/eid2946

Also see https://www.rfc-editor.org/errata/eid1739

P.
On 19/09/2023 09:49, [e-mail]<mailto:[e-mail]> wrote:
Hi all,

The description of these IEs says that "Options are mapped to bits according to their option numbers. Option number X is mapped to bit X", however the drawing does not reflect that (tcpOptions):

        0     1     2     3     4     5     6     7
    +-----+-----+-----+-----+-----+-----+-----+-----+
    |   7 |   6 |   5 |   4 |   3 |   2 |   1 |   0 |  ...
    +-----+-----+-----+-----+-----+-----+-----+-----+

        8     9    10    11    12    13    14    15
    +-----+-----+-----+-----+-----+-----+-----+-----+
... |  15 |  14 |  13 |  12 |  11 |  10 |   9 |   8 |...
    +-----+-----+-----+-----+-----+-----+-----+-----+

       16    17    18    19    20    21    22    23
    +-----+-----+-----+-----+-----+-----+-----+-----+
... |  23 |  22 |  21 |  20 |  19 |  18 |  17 |  16 |...
    +-----+-----+-----+-----+-----+-----+-----+-----+

                          . . .

       56    57    58    59    60    61    62    63
    +-----+-----+-----+-----+-----+-----+-----+-----+
... |  63 |  62 |  61 |  60 |  59 |  58 |  57 |  56 |
    +-----+-----+-----+-----+-----+-----+-----+-----+

I suspect that the confusion is rooted in the interpretation of "bit X": as (1) "bit position X" or the resulting (2) "binary value":

  1.  If (1) is followed, then bit#0 would be mapped to option 0, bit#1 to option 1, and so on. This logic is followed, e.g., for ipv6ExtensionHeaders.
  2.  If (2) is followed, then bit#63 would be mapped to option 0, bit#62 to option 1, and so on.

In both cases, the drawing is not aligned with the narrative text. We may either consider updating the drawing or the text.

Which change is likely to have less impact on existing implementations? FWIW, (1) is what was followed in RFC5102 but changed since then by errata.

Thank you.

Cheers,
Med

____________________________________________________________________________________________________________

Ce message et ses pieces jointes peuvent contenir des informations confidentielles ou privilegiees et ne doivent donc

pas etre diffuses, exploites ou copies sans autorisation. Si vous avez recu ce message par erreur, veuillez le signaler

a l'expediteur et le detruire ainsi que les pieces jointes. Les messages electroniques etant susceptibles d'alteration,

Orange decline toute responsabilite si ce message a ete altere, deforme ou falsifie. Merci.



This message and its attachments may contain confidential or privileged information that may be protected by law;

they should not be distributed, used or copied without authorisation.

If you have received this email in error, please notify the sender and delete this message and its attachments.

As emails may be altered, Orange is not liable for messages that have been modified, changed or falsified.

Thank you.

____________________________________________________________________________________________________________
Ce message et ses pieces jointes peuvent contenir des informations confidentielles ou privilegiees et ne doivent donc
pas etre diffuses, exploites ou copies sans autorisation. Si vous avez recu ce message par erreur, veuillez le signaler
a l'expediteur et le detruire ainsi que les pieces jointes. Les messages electroniques etant susceptibles d'alteration,
Orange decline toute responsabilite si ce message a ete altere, deforme ou falsifie. Merci.

This message and its attachments may contain confidential or privileged information that may be protected by law;
they should not be distributed, used or copied without authorisation.
If you have received this email in error, please notify the sender and delete this message and its attachments.
As emails may be altered, Orange is not liable for messages that have been modified, changed or falsified.
Thank you.