Subject: [IPFIX] Errata 1738

From: Paul Aitken <[email-masked]>
Date: Wed, 17 Aug 2011 12:09:24 +0100

Dear IPFIX experts,

RFC 5102, section "5.8.6. ipv6ExtensionHeaders", provides the following 
table:

          Bit    IPv6 Option   Description

        0, Res               Reserved
        1, FRA1     44       Fragmentation header - not first fragment
        2, RH       43       Routing header
        3, FRA0     44       Fragment header - first fragment
        4, UNK               Unknown Layer 4 header
                             (compressed, encrypted, not supported)
        5, Res               Reserved
        6, HOP       0       Hop-by-hop option header
        7, DST      60       Destination option header
        8, PAY     108       Payload compression header
        9, AH       51       Authentication Header
       10, ESP      50       Encrypted security payload
       11 to 31              Reserved

The intention was to encode each header in the corresponding bit per the 
table, so FRA1 would be 2^1, RH would be 2^2, UNK would be 2^4 etc.
So from a programming point of view, the bits should be:

            7      6      5      4      3      2      1      0
        +------+------+------+------+------+------+------+------+
    ... | DST  | HOP  | Res  | UNK  | FRA0 |  RH  | FRA1 | Res  |
        +------+------+------+------+------+------+------+------+

Unfortunately RFCs number the bits in the opposite order, so what we 
drew in RFC 5102 was:

           0     1     2     3     4     5     6     7
        +-----+-----+-----+-----+-----+-----+-----+-----+
        | Res | FRA1| RH  | FRA0| UNK | Res | HOP | DST |  ...
        +-----+-----+-----+-----+-----+-----+-----+-----+

- which is exactly the opposite of what was intended. The text is right, 
but the figure is backwards. Per the errata, "The diagram is back to front."

I tried to correct this in Errata 1737: 
http://www.rfc-editor.org/errata_search.php?eid=1737

Unfortunately I only flipped the bits around inside the bytes without 
flipping the bytes around too.

What the errata should say is:

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

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

              16    17    18    19    20    21    22    23
           +-----+-----+-----+-----+-----+-----+-----+-----+
       ... |         Reserved            | ESP | AH  | PAY | ...
           +-----+-----+-----+-----+-----+-----+-----+-----+

              24    25    26    27    28    29    30    31
           +-----+-----+-----+-----+-----+-----+-----+-----+
       ... | DST | HOP | Res | UNK | FRA0| RH  | FRA1| Res |
           +-----+-----+-----+-----+-----+-----+-----+-----+

Note that the network bit numbering in the figure is exactly the reverse 
of the "Bit" value in the table - so it might be better to rename "Bit" 
as "position".

P.

---

From: "Romascanu, Dan (Dan)" <[email-masked]>
Date: Wed, 17 Aug 2011 14:27:02 +0200

Thanks, Paul. This seems OK to me now. I would also like to know if any
of the IPFIX experts sees any problem with this fix - before we enter
and approve a new erratum. 

Regards,

Dan

> -----Original Message-----
> From: Paul Aitken [mailto:[email-masked]]
> Sent: Wednesday, August 17, 2011 2:09 PM
> To: IETF IPFIX Working Group
> Cc: Romascanu, Dan (Dan)
> Subject: Errata 1738
> 
> Dear IPFIX experts,
>

---

From: Paul Aitken <[email-masked]>
Date: Wed, 17 Aug 2011 14:05:52 +0100

Dan,

Note that the same applies to 1737, 1738 and 1739.

I've written about 1737 and 1738.

The revised figure for 1739 would be like so:

               0     1     2     3     4     5     6     7
           +-----+-----+-----+-----+-----+-----+-----+-----+
           |  63 |  62 |  61 |  60 |  59 |  58 |  57 |  56 |  ...
           +-----+-----+-----+-----+-----+-----+-----+-----+

                                 . . .

              56    57    58    59    60    61    62    63
           +-----+-----+-----+-----+-----+-----+-----+-----+
       ... |   7 |   6 |   5 |   4 |   3 |   2 |   1 |   0 |
           +-----+-----+-----+-----+-----+-----+-----+-----+

P.

---

From: Paul Aitken <[email-masked]>
Date: Fri, 19 Aug 2011 15:34:08 +0100

Dan,

> and approve a new erratum.

There was no reply.

Shall I proceed with 3 new errata?

P.

---

From: "Romascanu, Dan (Dan)" <[email-masked]>
Date: Sun, 21 Aug 2011 17:02:27 +0200

Yes, please!

Regards,

Dan

> Sent: Friday, August 19, 2011 5:34 PM
> To: Romascanu, Dan (Dan)
> Cc: IETF IPFIX Working Group
> Subject: Re: Errata 1738
> 
> Dan,
>

---

From: Nevil Brownlee <[email-masked]>
Date: Mon, 22 Aug 2011 10:32:42 +1200

Hi all:

Now that I've had a chance to look carefully at Paul's errata,
they do indeed seem OK to me.  I think we should indeed make these
changes now, so as to make the documents correspond exactly with
what we'd intended.

Cheers, Nevil

On 22/08/11 3:02 AM, Romascanu, Dan (Dan) wrote:
> _______________________________________________
> IPFIX mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/ipfix

-- 
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  Nevil Brownlee                    Computer Science Department | ITS
  Phone: +64 9 373 7599 x88941             The University of Auckland
  FAX: +64 9 373 7453   Private Bag 92019, Auckland 1142, New Zealand

---

From: Brian Trammell <[email-masked]>
Date: Mon, 22 Aug 2011 07:32:46 +0200

+1

(my previous message on this seems to have been lost, but didn't really have any more content...)

Cheers,

Brian

---

From: Brian Trammell <[email-masked]>
Date: Fri, 19 Aug 2011 19:34:12 +0200

Sorry, these were still in my queue.

on quick review, these are good.

cheers, B

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