[SIS-CFDPV1] updated CFDP Revisions draft

[구철회]

Hi Scott,
Thank you for the changes. Please find my comments as follows;

1) Section 4.1.2
Is it more clear when target PDU format is specified? i.e.
When an entity is required to perform checksum calculation of a given type but is for any reason unable to do so, the value of the checksum shall be zero.
to
When an entity is required to perform checksum calculation of a given type but is for any reason unable to do so, the value of the file checksum in the EOF PDU shall be zero.

Or I would think it is helpful if receiving entity is able to know that the file checksum in the EOF PDU to be received will be zero because in that case receiving entity don’t have to calculate checksum incrementally, which I believe some agencies perform it for time saving because it could be an issue when big file is transferred. So would it make sense?

When an entity is required to perform checksum calculation of a given type but is for any reason unable to do so, the value of the checksum shall be zero.
to
When an entity is required to perform checksum calculation of a given type but is for any reason unable to do so, the checksum type in the Metadata PDU and the value of the file checksum in the EOF PDU shall be zero.
If so, the default checksum type for modular checksum should be ‘1’ or so.

2) Section 5.2.5
I think that 6 for the length of checksum type is too long and some space could be requested for future use. In my opinion, for interoperable operation an applicable checksum algorithm should be selectable among 2 or 3, which each agency should implement as minimum and mandatory.

FYI, for example checksum type could be 3 bit for length and value are as follows;
   - 0 (no checksum type or checksum operation is not applicable at current transaction)  ; I think at the last CCSDS meetings, we discussed the checksum type of zero (0) would be no checksum, 1 for modular checksum, 2 for CRC32 and so on.
   - 1 (CFDP mandatory checksum type #1)
- 2 (CFDP mandatory checksum type #2)
- 3 (CFDP mandatory checksum type #3)
- 4 ~ 7 (CFDP user defined checksum type #1 ~ #4)

Best,

Cheol


From: SIS-CFDPV1 <sis-cfdpv1-bounces at mailman.ccsds.org> On Behalf Of Burleigh, Scott C (312B) via SIS-CFDPV1
Sent: Saturday, May 25, 2019 5:17 AM
To: sis-cfdpv1 at mailman.ccsds.org
Cc: osvaldo.peinado at dlr.de; madalier at antarateknik.com; jens.janssen at dlr.de; Thomas Gannett <thomas.gannett at tgannett.net>; Jeremy.Mayer at dlr.de; Cola, Tomaso (Tomaso.deCola at dlr.de) <Tomaso.deCola at dlr.de>
Subject: [SIS-CFDPV1] updated CFDP Revisions draft

Hi, all.  I have made all the changes to the revised CFDP Blue Book that I think are needed in order to make the file checksum algorithm selectable by reference to the new SANA checksum algorithm registry.  The updated document is now in CWE at https://cwe.ccsds.org/sis/docs/SIS-CFDPV1/Draft%20Documents/727x0b5%20--%20Specification%20--%20Blue%20Book/727x0p42_working%202.doc?Web=1.  Please take a look at it when you have a moment; I’d like to send a final draft to Tom and ask for a supplementary Agency review soon, maybe as early as next month.

Scott
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.ccsds.org/pipermail/sis-cfdpv1/attachments/20190527/9038f3ea/attachment.html>