[Sls-slp] Proposal: Add the CLCW to the Generic Session Control Book 235.1

Sun Jun 15 18:00:13 UTC 2025

Matt,
I am fine with not putting the CLCW definition into the Session Control Book. Maybe at some future date one might have a reason to do so but not now.
Regards,
Greg

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From: SLS-SLP <sls-slp-bounces at mailman.ccsds.org> on behalf of Matt Cosby via SLS-SLP <sls-slp at mailman.ccsds.org>
Sent: Sunday, June 15, 2025 8:40:28 AM
To: Kazz, Greg (US 312B) via SLS-SLP <sls-slp at mailman.ccsds.org>
Subject: [EXTERNAL] Re: [Sls-slp] Proposal: Add the CLCW to the Generic Session Control Book 235.1

PUBLIC

Greg,

I tend to agree with your approach… however, we are limited session control to COP-P, not COP-1… so although this is not an issue for TC, as this is not allowed to be used for the session control, we are limited its use by AOS…

Is that what we want to do?

Cheers,

Matt.

Matthew Cosby

Chief Technology Officer

Goonhilly Earth Station Ltd

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From: SLS-SLP <sls-slp-bounces at mailman.ccsds.org> On Behalf Of Kazz, Greg (US 312B) via SLS-SLP
Sent: 15 June 2025 03:36
To: Kazz, Greg (US 312B) via SLS-SLP <sls-slp at mailman.ccsds.org>
Subject: [Sls-slp] Proposal: Add the CLCW to the Generic Session Control Book 235.1

Dear SLP WG,

On topic we didn’t address during our Spring ’25 SLP WG meeting this past week at APL, was Tom Gannett’s suggestion, that the TC COMMUNICATIONS LINK CONTROL WORD(CLCW) be added as a separate chapter to the Generic Session Control Book, 235.1.

I would like to get your opinion regarding this additional reorganization step. I will state my opinion below as well.

This was Tom’s suggestion below:

[Tom Gannett] Specifically, I would create a new section in the Generic Session Control book, Section 3, Protocol Data Units; move 4.2.1, COMMUNICATIONS LINK CONTROL WORD from TC SDLP to subsection 3.1 in the Session book; and move SUPERVISORY to subsection 3.2 in the Generic Session Control book:

1              INTRODUCTION

2              OVERVIEW

3              PROTOCOL DATA UNITS

3.1          COMMUNICATIONS LINK CONTROL WORD

3.2          SUPERVISORY PROTOCOL DATA UNIT

4              DATA SERVICES OPERATIONS

4.1          STATE TABLES

                ETC.

I believe this is a clean approach that would make COP services and session control available without the need to invoke the PDU format specifications in TC SDLP and Proximity-1, but I have not looked at all potential ramifications in all Data Link Layer specs. . . .

All the cross references to CLCW/PLCW/SPDU in the source books would be changed to direct references to the Session book; current references in the COPs to CLCW/PLCW/SPDU in the source SDLP books would be changed to references to the Session book.

TC SLDP would have to be pink sheeted, and any books currently referencing TC SDLP for COP-related stuff would need to updated (via corrigendum probably).

[Greg] This approach that Tom is advocating would make the COP-1 control word generic (CLCW), but would add Telecommand to the Session book, which currently isn’t used in a generic sense like Prox-1, USLP, and AOS. TC SDLP really should not have the CLCW defined in it, since the TC Frame is the defacto PDU of that document. However, given the high priority to generate the Session Control book, it seems currently, there is not a big driver to create this separate 3.1 CLCW chapter in the Session book, mainly because Telecommand isn’t envisioned to have session control. So from my point of view, there is no action to be taken here.

Your thoughts ?

Best regards,

Greg

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