[Sls-slp] A Mission Proposal - AOS Transfer Frames over Proximity-1 Session Control

[Marco Rovatti]

Hi Greg,

I haven’t spoken with Moonlight people yet and I had not attended the meeting mentioned by Ignacio held a couple of days ago as I was not involved, therefore I’m only speculating here. I  will coordinate internally with Moonlight and Ignacio to get a better picture.
In any case, I still don’t get what kind of problem Moonlight project is trying to solve by using AOS over Prox-1.
At a first glance it seems that they will get into more troubles than those they want to fix, but, again, pending listening to Moonlight opinions.
In fact, AOS is fixed length frames and does not support COP.
In the end, it might work with workarounds, however I would not recommend it.

Preferred options:

  1.  Use prox-1 frames OR
  2.  Use USLP

Cheers
Marco

From: SLS-SLP <sls-slp-bounces at mailman.ccsds.org> On Behalf Of Kazz, Greg (US 312B) via SLS-SLP
Sent: 22 May 2023 19:42
To: Kazz, Greg (US 312B) via SLS-SLP <sls-slp at mailman.ccsds.org>
Subject: [Sls-slp] A Mission Proposal - AOS Transfer Frames over Proximity-1 Session Control

Dear SLP WG,

A question has come to me via the ESA Moonlight mission regarding the feasibility of using the AOS Space Data Link Protocol over the Proximity-1 session control (state tables that control link establishment, data exchange, and link termination).

I would like to know your opinion on this question: What does the SLP WG think about the possibility of using the AOS transfer frame format with Prox-1 session control ?

Here are my thoughts below:

Pro:

As you may know from our last meeting, the WG is attempting to split the Prox-1 SDLP book into a separate session control book, separate COP-P book, and a separate transfer frame PDU book, that one similar to the existing TC, TM, AOS books. If we succeed in that endeavor, it would be much easier for a mission to swap in different CCSDS data link layer protocols below the Prox-1 session control sublayer.

Con:

However, all the fine details to ensure dividing up the Prox-1 books has not yet been worked out by the SLP WG. This really has only been done for USLP and Prox-1. Nor has any interoperability testing been accomplished as well to clearly demonstrate interoperability. Therefore, it would be the responsibility of each and every mission to take on that additional risk, if they were to use AOS for example with Prox-1 session control. Lastly, CCSDS created USLP in order to do just that – replace AOS, TM, TC, Prox-1 with one link layer PDU useable in all venues. USLP has been interoperability tested by CCSDS.

We have a short fuse of two weeks to gather our inputs to this question, so I appreciate a quick response back from you all.

Best regards,

Greg – Chairman CCSDS SLP WG

Greg Kazz
Principal Engineer
Technical Group Supervisor,
312B Project Protection, Project Software, and End to End Information System Engineering
Jet Propulsion Laboratory
4800 Oak Grove Dr., M/S 301-490
Pasadena, CA 91109
1+(818)393 6529(voice)
1+(818)393 6871(fax)
email: greg.j.kazz at jpl.nasa.gov<mailto:greg.j.kazz at jpl.nasa.gov>

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