[CESG] CESG-P-2023-07-001 Approval to release CCSDS 732.1-P-2.1, Unified Space Data Link Protocol (Sheets, Issue 2.1) for CCSDS Agency review

[CCSDS Secretariat]

Dear CESG Members,

Conditions for approval of CCSDS 732.1-P-2.1, Unified Space Data Link Protocol (Sheets, Issue 2.1) have been disposed to the satisfaction of the AD(s) who voted to approve with conditions. The Secretariat will now proceed with CMC polling to authorize release for Agency review.
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From:	Shames, Peter M (US 312B) <peter.m.shames at jpl.nasa.gov>
Sent:	Thursday, August 10, 2023 5:43 PM
To:	Kazz, Greg (US 312B); Thomas Gannett
Subject:	Re: [EXTERNAL] CESG poll to approve release of CCSDS 732.1-P-2.1, Unified 
Space Data Link Protocol (Pink Sheets, Issue 2.1) for CCSDS Agency review

Categories:	Poll Condition Closure

Thanks.  That works for me.

Peter


From: Greg Kazz <greg.j.kazz at jpl.nasa.gov> 
Date: Thursday, August 10, 2023 at 2:31 PM 
To: Peter Shames <peter.m.shames at jpl.nasa.gov>, Tom Gannett 
<thomas.gannett at tgannett.net> 
Subject: Re: [EXTERNAL] CESG poll to approve release of CCSDS 732.1-P-2.1, Unified Space Data 
Link Protocol (Pink Sheets, Issue 2.1) for CCSDS Agency review

Agreed.

Tom – Please add a note to the bottom of 6.5.2.2 Discussion as follows:

Note: These error conditions are detected either by the FARM and/or by the Frame Validation Check 
Procedure. To understand the reporting mechanisms with the FARM, one would go either to COP-1 Blue 
book or COP-P (currently within Prox-1 211.0) and examine the various frame rejection cases. These are 
reported in the CLCWs. Additionially and for links without ARQ, frame sequence counters are used to 
detect transfer frame gaps. For non-ARQ links, gaps are not reported but are detected by the receiving 
side via the frame sequence counter.

Thanks,
Greg

From: "Shames, Peter M (US 312B)" <peter.m.shames at jpl.nasa.gov> 
Date: Thursday, August 10, 2023 at 2:16 PM 
To: "Kazz, Greg (US 312B)" <greg.j.kazz at jpl.nasa.gov>, Thomas Gannett 
<thomas.gannett at tgannett.net> 
Subject: Re: [EXTERNAL] CESG poll to approve release of CCSDS 732.1-P-2.1, Unified Space Data 
Link Protocol (Pink Sheets, Issue 2.1) for CCSDS Agency review

Hi Greg,

From my PoV it would be better if in this document you stated that not only are the frames discarded, 
but that this is reported in the CLCW.

And my answer is yes to this question: “For non-ARQ links, gaps are not reported but are detected by 
the receiving side. Is a note to this effect warranted here ?”

Agreed?

I recognize that you do not want to repeat all of the contents of another spec every time one is 
referenced.  That said, if you are referencing a spec, as a sort of “black box”, I think it prudent to at least 
state what the gozintas and gozoutas are and what error conditions are signalled.

Thanks, Peter


From: Greg Kazz <greg.j.kazz at jpl.nasa.gov> 
Date: Thursday, August 10, 2023 at 11:00 AM 
To: Tom Gannett <thomas.gannett at tgannett.net>, Peter Shames 
<peter.m.shames at jpl.nasa.gov> 
Subject: Re: [EXTERNAL] CESG poll to approve release of CCSDS 732.1-P-2.1, Unified Space Data 
Link Protocol (Pink Sheets, Issue 2.1) for CCSDS Agency review

Hi Tom,

I searched the CESG copy of USLP and could only find this one comment by Peter (other than the typos 
you mentioned) highlighted in yellow. I put it into the attachment, but also reproduced it here with my 
response. If there is more, please let me know.

Peter – Please let us know if my response is sufficient ?

6.5.2.2 Discussion
*	The Frame Validation Check Procedure within the All Frames Reception Function includes the 
check of the FECF, if it is present. A transfer frame that fails any of these checks is discarded. 
*	FARM-1 function: the FARM-1 specified in reference [9] uses the Frame Sequence Number in 
the Primary Header of an incoming Type-A Transfer Frame to perform the Frame Acceptance 
Checks. If the checks indicate that the frame is out of sequence, FARM-1 discards the frame. 
Peter: “I’m a little surprised that the FVCP and FARM both silently discard frames.  Where are these 
error conditions caught and reported?”

Greg: Purpose was not to reproduce the FVCP and FARM procedures here, but to give sufficient 
background about the functionality. 1) These error conditions are detected either by the FARM and/or 
by the FVCP. To understand the reporting mechanisms with the FARM, one would go either to COP-1 
Blue book or COP-P (currently within Prox-1 211.0) and examine the various frame rejection cases. 
These are reported in the CLCWs. Additionally and for links without ARQ, frame sequence counters are 
used to detect transfer frame gaps. For non-ARQ links, gaps are not reported but are detected by the 
receiving side. Is a note to this effect warranted here ?

Thanks much,
Greg






From: Thomas Gannett <thomas.gannett at tgannett.net> 
Date: Thursday, August 10, 2023 at 10:18 AM 
To: "Kazz, Greg (US 312B)" <greg.j.kazz at jpl.nasa.gov> 
Cc: "Shames, Peter M (US 312B)" <peter.m.shames at jpl.nasa.gov> 
Subject: [EXTERNAL] CESG poll to approve release of CCSDS 732.1-P-2.1, Unified Space Data 
Link Protocol (Pink Sheets, Issue 2.1) for CCSDS Agency review

Greg:

Peter has some conditions for approval of the USLP pink sheets. In order to complete agency review 
prior to the fall meetings, the CMC poll will have to begin by the end of next week. So can you work with 
Peter to resolve his conditions within the next few days, like, by Tuesday next week? (I will fix any 
identified typos.)

Tom


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