[Sls-sea-dls] SDLS BB : proposal for PS comments dispositions
Moury Gilles
Gilles.Moury at cnes.fr
Fri Aug 21 16:06:48 UTC 2015
Dear SDLS WG members,
Please find attached a redline version of the SDLS BB with proposed dispositions for Peter Shames comments (in line with my herebelow mail). The text modifications are tentatively justified wrt Peter's comment. We should converge internally to the WG before sending the proposed redline to Peter Shames. Craig, as technical editor of the book, could you please take the lead on this ? I am leaving for one week so will not be able to make any progress.
Best regards,
Gilles
Gilles MOURY
SDLS WG Co-Chair
De : sls-sea-dls-bounces at mailman.ccsds.org [mailto:sls-sea-dls-bounces at mailman.ccsds.org] De la part de Moury Gilles
Envoyé : mercredi 19 août 2015 15:45
À : Daniel.Fischer at esa.int; Ignacio.Aguilar.Sanchez at esa.int
Cc : sls-sea-dls at mailman.ccsds.org; sls-sea-dls-bounces at mailman.ccsds.org
Objet : RE: [Sls-sea-dls] results of CESG poll for SDLS BB publication
Dear Daniel, Ignacio and SDLS WG members,
I concur with Ignacio and Daniel proposals for Peter's comments disposition. More specifically, taking Peter's comments one by one (I attach Peter's commented version for reference):
P 1-1 : OK for the 2 comments
P 1-3, 3-1 : The usage of the term Payload: this term is duly defined upfront in SDLS book and therefore this definition replaces the CCSDS generic definition in the context of SDLS. The term is used consistently throughout the document. Besides the term payload is widely used with that meaning in the COMSEC domain. I agree with Ignacio and Daniel that we should discuss this with Peter and advocate for keeping this term.
P 2-1 : Comment not understood. To be discussed with Peter. In any case we can remove the parenthesis in the note if that causes problem.
P 2-2 : I do not support inserting in SDLS a duplicate of figures 6-1 of TM, TC and AOS books, but we could simply refer/point to it respectively in sections 2.2.3, 2.2.4 and 2.2.5 with a statement like: "the structure of the TM/TC/AOS Transfer Frame with SDLS is given in Figure 6-1 of [1]/[2]/[3]. This statement could also be placed once in section 2.3.1.4 Security Header and Trailer.
P 2-5 : Figure 2-4 : we need to change A and B to AOS ApplySecurity payload or return (instead of TM ApplySecurity ...)
P2-8, 4-9, 4-12 : NOTE on sequence number rollover : I would suggest keeping the NOTE but limiting it to the first sentence (The interpretation of a sequence number rollover (to zero) is mission specific) and then pointing to a specific SDLS green book subsection where this is discussed in more details. This would avoid confusion for implementers making it clear there is no specific recommendation (should) or permission (may) for that subject in the Blue Book.
P 3-7, 3-10 : SA management service: I would propose keeping subsection 3.4.2 intact (SA management service parameters). Replace the NOTE in 3.4.3 (SA management service directives) by : "The directives for SA management will be specified in a CCSDS recommendation currently under development (355.1-B: SDLS extended procedures)." To be coherent with that, I would replace the second sentence of subsection 3.4.1 by: "The service directives necessary
to manage the SA parameters will be specified in a CCSDS recommendation currently under development (355.1-B: SDLS extended procedures)". As suggested by Daniel, we could add a column in table 6-1 to indicate the correspondence between parameters denomination in subsection 3.4.2 and in Table 6-1.
P 5-1: Peters comment: (no mention of payload in that section 5 "Use of the services with CCSDS protocols"). I would propose to show the "ApplySecurity payload" in figures 5-1 (TM transfer frame), 5-2 (TC), 5-3 (AOS).
P 6-1 : OK to add unspecified (an unspecified management system). For the second comment (abstract SA data base) I tend to agree with Daniel, the SA data base is not abstract . It has to be implemented both on-ground and on-board.
P B-1 : OK to replace "user-supplied data unit" by "transfer frame data field" to make it unambiguous.
I hope we can converge with Peter on commonly agreed dispositions. We need to consolidate first our WG responses to his comments. Craig : let us know your position wrt the comments, so we can produce a redline version of the document with our proposed dispositions and associated explanations inserted.
Best regards,
Gilles
Gilles MOURY
CNES Toulouse
De : Daniel.Fischer at esa.int<mailto:Daniel.Fischer at esa.int> [mailto:Daniel.Fischer at esa.int]
Envoyé : jeudi 13 août 2015 14:51
À : Ignacio.Aguilar.Sanchez at esa.int<mailto:Ignacio.Aguilar.Sanchez at esa.int>
Cc : Moury Gilles; sls-sea-dls at mailman.ccsds.org<mailto:sls-sea-dls at mailman.ccsds.org>; sls-sea-dls-bounces at mailman.ccsds.org<mailto:sls-sea-dls-bounces at mailman.ccsds.org>
Objet : Re: [Sls-sea-dls] results of CESG poll for SDLS BB publication
Dear Igancio and all,
I checked the comments as well. I agree to all you say below and I have a few more remarks/ first thoughts based on the comments that Peter put in-line in the document.
1) The word payload: While of course it has different meanings, the term "payload" is very well established in the communication protocol world. You can find the following definition e.g. on Wikipedia: Payload in computing<https://en.wikipedia.org/wiki/Computing> (sometimes referred to as the actual or body data) is the cargo of a data transmission<https://en.wikipedia.org/wiki/Data_transmission>. It is the part of the transmitted data<https://en.wikipedia.org/wiki/Data_(computing)> which is the fundamental purpose of the transmission, to the exclusion of information sent with it (such as headers<https://en.wikipedia.org/wiki/Header_(computing)> ormetadata<https://en.wikipedia.org/wiki/Metadata>, sometimes referred to as overhead data) solely to facilitate delivery.
2) Regarding the inline comments:
P 1-1: I am not sure about both comments. Is this section not a standard CCSDS section? It reads like one. If yes, I would not bother modifying it.
P 1-3: See payload discussion
P 2-1: I am not sure I understand the comment. We simply state that SDLS is not associated with any other protocol and as an example we bring the SPP. This may be a misunderstanding. Perhaps Peter confuses an association with another protocol (e.g. for extended procedures) with the concept of the underlying data-link layer protocol(s). If this causes too much discussion, we could even remove the note.
P 2-2: Following up on Ignacios comments, i would not include too much additional information here. We have the Green Book for that. Also, the other SLS books that have been updated mention SDLS and how it fits in as well.
P 2-8: OK, I can see where he is coming from regarding the comment on the counter rollover. However, I think the note is pretty clear on this by saying the interpretation is mission-specific. We could think about being more concrete on this in the Green Book (if this is not already the case) and explain the benefits of not rolling over and how this can related to key lifetime.
P 3-7/3-10: I dont think that this section is an issue. Regarding the parameters, I think together with Section 6 (Managed Parameters) it makes sense to have them defined here. The only think that I agree may cause confusion is the paramater naming. E.g: Section 3.4.2.2 says "SA_authentication_key" while Section 6 says "Authentication Key". Maybe we could add a column to the table on Section 6, referring to the names used in Section 3.4.2.2. Regarding Section 3.4.3, I would almost be tempted to remove the Section from the standard (it is empty and the note will be out of date once the extended procedures...which are not a "revision" of the SDLS standard, but an addon...are out. We could pick this up in the Green Book.
P 6-1: (1) Not sure why we should add "unspecified". Did he want to say st. like "not covered by this standard?"...TBD (2) The SA database is not abstract. In fact it has to be very concrete if you want to do an implementation. Our prototype has one.
3) I think we should seek to have telcon with Peter not too far in the future to discuss his comments and not wait three months for the next meetings. This way, we could speed up the publication process a bit. What do you think?
Cheers
Daniel
Dr. Daniel Fischer
----------------------------
Data Systems Manager
Ground Systems Engineering Support Office
Ground Systems Engineering Department
Directorate of Human Spaceflight and Operations
European Space Agency - ESOC
Robert-Bosch-Str. 5
D-64293 Darmstadt - Germany
Tel: +49 (0) 6151 90 2718 - Fax: +49 (0) 6151 90 2718
Web: http://www.esa.int<http://www.esa.int/>
From: Ignacio.Aguilar.Sanchez at esa.int<mailto:Ignacio.Aguilar.Sanchez at esa.int>
To: Moury Gilles <Gilles.Moury at cnes.fr<mailto:Gilles.Moury at cnes.fr>>,
Cc: "sls-sea-dls at mailman.ccsds.org<mailto:sls-sea-dls at mailman.ccsds.org>" <sls-sea-dls at mailman.ccsds.org<mailto:sls-sea-dls at mailman.ccsds.org>>
Date: 13/08/2015 13:35
Subject: Re: [Sls-sea-dls] results of CESG poll for SDLS BB publication
Sent by: sls-sea-dls-bounces at mailman.ccsds.org<mailto:sls-sea-dls-bounces at mailman.ccsds.org>
________________________________
Dear Gilles and colleagues,
I believe the comment from Tomaso, supported by Keith, is easy to deal with
the inclusion of such note.
Concerning Peter's comments,
1) We all agreed and supported harmonisation of the SDLS with the SLPs, Part
of the agreement was the assumption that the potential user shall start
reading the SLPs before getting to the SDLS (since it is a NEW optional SLP
function). And we (SLP WG + SDLS WG) were very careful in deciding what to
put where. This can explain why the SDLS does not read so well stand-alone,
as Peter seems to want.
Including the three different scenarios (TC, TM, AOS) with corresponding
drawings into the SDLS will substantially 'inflate' the introduction.
And will risk causing incoherency issues with the SLPs and the still-to-be
published SDLS Green Book.
I think the issue needs to be re-discussed with Peter since the drawings are
already at the documents where they are supposed to be.
2) The word 'payload' is mentioned 72 times in the document. The last mention
is in paragraph B1.1, which is perhaps the one that I can see somewhat
inconsistent but it should be easy to fix. Hence, I beg to disagree with
Peter concerning inconsistency in its use. A different thing is whether
another term could be used to avoid confusion with the classical meaning of
payload in space missions but I think the meaning in SDLS is pretty clear and
defined. On his proposals "package" looks too close to "packet" and "user
provided data" too close to "service data unit" (note that the 'payload' as
in SDLS context includes the SDU and something else, hence not a valid
substitute).
Unless someone finds a clear and unambiguous term to replace 'payload' in the
SDLS context, I would advocate to re-discuss the comment with Peter.
3) If the document has to be self-standing concerning its interpretation,
this is definitely a section that I think should stay. It is addressing a
core element of the SDLS. The Green Book will provide further elaboration but
a bare minimum is needed to be able to understand and interpret SDLS.
4) There are three NOTES covering this issue that are consistent. I think we
did not want to impose requirements in this subject, reason why they are
notes. But we could change it to requirements with the word 'may' to make
them more visible as suggested by Peter.
I hope the above helps.
Kind regards,
Ignacio
From: Moury Gilles <Gilles.Moury at cnes.fr<mailto:Gilles.Moury at cnes.fr>>
To: "sls-sea-dls at mailman.ccsds.org<mailto:sls-sea-dls at mailman.ccsds.org>" <sls-sea-dls at mailman.ccsds.org<mailto:sls-sea-dls at mailman.ccsds.org>>
Date: 13/08/2015 11:01
Subject: [Sls-sea-dls] results of CESG poll for SDLS BB publication
Sent by: sls-sea-dls-bounces at mailman.ccsds.org<mailto:sls-sea-dls-bounces at mailman.ccsds.org>
Dear CCSDS SDLS WG member,
Please find attached 2 files:
The results of the CESG poll (as of today - it terminates tomorrow)
The commented version of the SDLS Blue Book attached to the comments of Peter
Shames (SEA AD)
We have to respond to those comments and resolve them with the issuer before
we can actually publish the BB. Please advise on the way to respond to those
comments.
Best regards,
Gilles MOURY
SDLS WG Co-Chair
=========================================================
Gilles MOURY
CNES Toulouse
Expert senior "Plateforme Satellite"
Sous-Direction "Techniques Véhicule, Architecture & Intégration"
DCT/TV-RA - Bpi 1416
18, avenue Edouard Belin
F-31401 TOULOUSE Cedex 9
http://www.cnes.fr<http://www.cnes.fr/>
tel : +33 (0)5 61 27 3790
fax : +33 (0)5 61 27 4099
sec : +33 (0)5 61 27 3882
mob : +33 (0)6 83 56 0485
=========================================================
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