Re: A puzzled maintainer with questions regarding

["M.Baris Demiray" <barisdemiray () gmail com>]

Hello,

On Thu, Feb 10, 2011 at 6:46 PM, Guy Harris <guy () alum mit edu> wrote:
> On Feb 6, 2011, at 10:17 PM, M.Baris Demiray wrote:
>
> > Unfortunately no, there is not. As in SIS Layer dissector this is also
> > a part of a standard which is available only to NATO member states
>
> Hey, I'm a citizen of a NATO member state.... :-)

Oh. :) But I would prefer to depict a DPDU header by words rather than
sending the part of the document (especially if DPDU headers are kept
intact in the new version, keep reading, explained in the next
paragraph) before ensuring that I'm authorised to do that.

> > and that therefore we access through an account. However there is a
> > version called 1.0.2 on the Internet and there you may find the
> > section C.3 Structure of sublayer protocol data units (D_PDUs) in
> > order to observe what a DPDU header looks like.  This is a really old
> > version and I think that's why it's unclassified. Here is the link,
> >
> > http://www.armymars.net/ArmyMARS/HF-Email/resources/stanag5066.pdf
> >
> > Besides this I will check if I can provide any recent versions of DPDU headers.
>
> OK, so the packets in this file are D_PDUs as described in that section?

Exactly, I've just compared DPDU headers described in two versions of
the document and the only difference is the new content of Extended
Field of Type 6 Management DPDU which was introduced by HFTRP (HF
Token Ring Protocol) to hold information such as Ring Address and
Number of Nodes in the Ring. And it's not a new field, just an
extended field placed by setting the Extended Message flag (p. 19).

> Do they begin with the 16-bit synchronization sequence, or is that stripped off, so that they begin with the header 
> field?  Do data PDUs include the CRC at the end, or is that stripped off?

16-bit synchronization sequence is sent over-the-air for all the types
of DPDUs so it's not stripped off. And for data PDUs, yes, they
include CRC at the end. So it's like below for data PDUs,

| SYNC | HEADER | HEADER_CRC | DATA | DATA_CRC |

And like below for control frames (namely DPDU types 1, 3, 5, 6, and 15),

| SYNC | HEADER | HEADER_CRC |

Cheers,

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-- 
M. Baris Demiray

Researcher
TUBITAK-UEKAE/G227
Design and Development Engineering Division

Tunali Hilmi Cad. Binnaz Sok. No:2 Kat:3
06700 Kavaklidere, ANKARA, Turkey

Phone :  (+90) 312-427-73 66 ext 128
Fax     :  (+90) 312-427-88 44
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