[Sea-sa] Agenda for SCCS-ARD Webex, scheduled for 1 Feb 2021 @ 745 AM PST
Shames, Peter M (US 312B)
peter.m.shames at jpl.nasa.gov
Thu Jan 28 21:56:49 UTC 2021
Dear SAWG colleagues – SCCS-ARD subset,
John Pietras has posted an update of the ARD that covers the points that we discussed and agreed on at the webex session earlier this month. These are in the CWE at:
There have been discussions related to this SCCS-ARD central topic in the weeks since the last meeting. These cover the FRM and EDS, and a special working meeting on the forward / return file service. Those support materials have been written to the SCCS-ARD CWE site in the Background Materials folder:
For the 1 Feb meeting there are more observations and questions about how the ABA ESLT Service Provider Building Block requirements (i.e., 220.127.116.11.1 and on) are currently phrased. Basically, the way they are currently stated they, too, don’t scale up well with the availability more “parallel” CCSDS standards. John would like to discuss those and make some suggested changes.
The agenda topics are:
1. Review the recent updates to sections 4.2, the tables in section 18.104.22.168, and the building block diagrams in section 22.214.171.124
2. Discuss restructuring/rephrasing of building block requirements in section 6
Please see below the final minutes from the 6 Jan 2021 meeting.
SCCS-ARD Revision Meeting Notes, 6 Jan 2021
Attendees: Peter Shames, John Pietras, Ramon Krosley, Yonghui Huang, Costin Radulescu
* Reviewed the “Issues” file that John Pietras prepared (see SCCS-ARD_Update-210104 file in CWE), including the overview of the proposed work and intended fixes.
* Specific issues were identified for three sections of the document. These are covered in the file and are just named here for reference, along with an decisions made during discussion:
* Sec 4: agreed to revise the style in which contents are presented, as suggested by John. This will result in the details of relevant protocol stacks to be moved to Sec 6 and just forward referenced in Sec 4.
* Sec 6: Modified approach to use two sets of tables.
* Mappings of services to protocols (used for cross references from section 4)
* Mappings of production functionality to protocols (used for cross references from section 5)
* Adopted other changes to Sec 6 protocol tables as discussed. This includes splitting out SLE/CSTS separate from the CFDP/TGFT protocols, largely because these are different in kind. Also agreed to other detailed changes in the handling of SCCC and DVB coding and modulation, since they are distinct from the “mainline” CCSDS coding, synch, and modulation standards.
* During the meeting we also discussed a couple of related topics, as follows:
* There is a push to not just incorporate a new “CFDP File Delivery Service”, which puts the CFDP agent into the ESLT, but also to augment that with a new kind of “lost segment signaling” and “retransmission request signaling” between the CFDP agent in the ESLT and the Earth User Node (EUN). These added signals, and the TGFP adaptation, constitute a whole new set of protocols which as, as yet, largely undefined.
* A separate request was made to the CSS and other areas involved in this to try and reach some clarity as to whether this really makes sense and just what is proposed, or planned. As separate discussion is being scheduled.
* It was noted that the kinds of configuration and control information that must be exchanged in order to make this CFDP File Delivery service work, given that it involves creating CFDP PDUs, packetizing them, creating data link frames, and encoding them in the ground station, starts to look a lot like the sorts of processing described in the DTN Last Hop and First Hop services described earlier. Those papers have been placed in the Background Materials folder for reference.
* The question of whether it makes sense to invest CCSDS resources in developing this new, rather restricted, new set of protocols or of that effort should go into refining the use of CFDP over DTN instead, which is a solid path into the future for a broader range of missions.
* Several other topics were briefly discussed at the beginning, and during, the meeting:
* Recognize that work must be done to sort out the relationships between the CSS Functional Resource Model (FRM), which was characterized as a database of knowledge about component functions that get assembled to provide services, and the SOIS Electronic Data Sheet (EDS), which was characterized as a way to document hardware and software component interfaces so as to facilitate development of software for those interfaces.
* Recognize that work must be done to disambiguate the different ‘flavors” of “service”: as in CSS services, arbitrary “application services” like packet transfer without formal application layer protocols, protocol layer Service Access Points (SAP), SM&C “Services”, service interface binding signatures, and the related protocol stacks that implement service transfers. Focus is to be on services, protocols, and interfaces and not on implementations.
* Discussed the effect of the relatively new Q-SCID specs, from CCSDS 320.0-M-7, and the new USLP protocol with its 16-bit SCID, on the existing SLE and CSTS protocols. This is apparently being addressed within the CSS area.
The files for review, and any added / background materials, will be placed in the CWE at: https://cwe.ccsds.org/sea/docs/Forms/AllItems.aspx?RootFolder=%2Fsea%2Fdocs%2FSEA%2DSA%2FDraft%20Documents%2FSCCS%2DARD%2DADD%20Revisions%202020&View=%7BA709F322%2D0E67%2D45C7%2D932D%2DCB78C55CE268%7D&&InitialTabId=Ribbon%2EDocument&VisibilityContext=WSSTabPersistence <https://urldefense.us/v3/__https:/cwe.ccsds.org/sea/docs/Forms/AllItems.aspx?RootFolder=*2Fsea*2Fdocs*2FSEA*2DSA*2FDraft*20Documents*2FSCCS*2DARD*2DADD*20Revisions*202020&View=*7BA709F322*2D0E67*2D45C7*2D932D*2DCB78C55CE268*7D&&InitialTabId=Ribbon*2EDocument&VisibilityContext=WSSTabPersistence*20__;JSUlJSUlJSUlJSUlJSUlJSUlJQ!!PvBDto6Hs4WbVuu7!dkq2FeTLx9sqJswtaTiN_Nv7x6sENZfbDvsYuqOYjkc9OVxL4cehx4WH3MeU4GQYNshqouU5$>
=> Next telecon, 1 Feb 2021: Review the refined approach for Sec 4 and Sec 6, to be produced by John Pietras, incorporating the agreed changes.
=> Peter Shames to setup a separate working session, with CSS, SLS, SIS and SEA, to look into the issues around the proposed CFDFP File Delivery service , as discussed above, and the DTN alternative.
=> Peter has set up sub-folders for background, draft docs, and working meeting minutes
=> Request for the team to familiarize with these background materials
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