[Sis-dtn] New Draft: COMPRESSED CUSTODY SIGNALING AND BUNDLE STATUS REPORTING

[Felix Flentge]

Hi Brian,

I have discussed with Yanik (who may still not have access to the CCSDS mailinglist...) and he came up with the following proposal:

In terms of wording, I think it would be clearer to keep the definition for
the Bundle Sequence Range as is and modify the definition for the Bundle Sequence instead.

I.e., we could append an "or a CBOR uint" to describe the Bundle Sequence Range (field).

This could e.g., look like:

Bundle Sequence Range - A Bundle Sequence Range as defined in 3.3.2 below
       or
       A CBOR unsigned integer if there is only a single sequence to be included, representing the length of that sequence



I suppose, put in CDDL, this could then look like this instead:

seq = [
  seq-id: uint / eid,
  seq-start: uint,
  range: seq-range / seq-incl-len,
  ? blk-source: eid
]
seq-range = [ seq-incl-len, + ( seq-excl-len, seq-incl-len) ]
seq-incl-len = uint .gt 0 ; inclusive length
seq-excl-len = uint .gt 0 ; exclusive length


Regards,
Felix

From: Sipos, Brian J. <Brian.Sipos at jhuapl.edu>
Sent: 15 May 2025 15:09
To: Felix Flentge <Felix.Flentge at esa.int>; sis-dtn at mailman.ccsds.org
Cc: Juan A. Fraire <juan.fraire at inria.fr>; Alice Le Bihan <alice.le-bihan at insa-lyon.fr>; Jeck, Yanik <yanik.jeck at cgi.com>; Kramp, Paul-Niklas <paul-niklas.kramp at cgi.com>
Subject: RE: New Draft: COMPRESSED CUSTODY SIGNALING AND BUNDLE STATUS REPORTING

Felix,
Thanks for consideration of my earlier suggestion. I think the definition of Bundle Sequence Range in Sec 3.3 is consistent and understandable.

There is one possible compression, saving one byte, in the case where the array would have a single uint item it can be substituted with the uint itself. It doesn't affect the information model being encoded, but does add a small coding / decoding overhead to apply the compression. So it's completely optional if you think there is that much value in one byte. (This compressed form would also degenerate to your earlier form of start + length if there are no excluded intervals)

Put in CDDL, the `seq-range` would include the following (with rule `eid` taken from RFC 9171 appendix)

seq = [
  seq-id: uint / eid,
  seq-start: uint,
  seq-range,
  ? blk-source: eid
]
seq-range = [ seq-incl-len, + ( seq-excl-len, seq-incl-len) ] / seq-incl-len
seq-incl-len = uint .gt 0 ; inclusive length
seq-excl-len = uint .gt 0 ; exclusive length


From: SIS-DTN <sis-dtn-bounces at mailman.ccsds.org<mailto:sis-dtn-bounces at mailman.ccsds.org>> On Behalf Of Felix Flentge via SIS-DTN
Sent: Wednesday, May 14, 2025 9:11 AM
To: Dr. Keith L Scott via SIS-DTN <sis-dtn at mailman.ccsds.org<mailto:sis-dtn at mailman.ccsds.org>>
Cc: Juan A. Fraire <juan.fraire at inria.fr<mailto:juan.fraire at inria.fr>>; Alice Le Bihan <alice.le-bihan at insa-lyon.fr<mailto:alice.le-bihan at insa-lyon.fr>>; Jeck, Yanik <yanik.jeck at cgi.com<mailto:yanik.jeck at cgi.com>>; Kramp, Paul-Niklas <paul-niklas.kramp at cgi.com<mailto:paul-niklas.kramp at cgi.com>>
Subject: [EXT] [Sis-dtn] New Draft: COMPRESSED CUSTODY SIGNALING AND BUNDLE STATUS REPORTING

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Hi,

I have just uploaded Draft H of the 'Compressed Custody Signaling And Bundle Status Reporting' Orange Book to CWE:

CompressedBundleStatusReportingAndCustodySignaling_OrangeBook_Draft_H.docx<https://spacecomm.sharepoint.com/:w:/r/sites/SIS/_layouts/15/Doc.aspx?sourcedoc=%7B10790F7B-6318-4BD0-9D53-8813C83BE941%7D&file=CompressedBundleStatusReportingAndCustodySignaling_OrangeBook_Draft_H.docx&action=default&mobileredirect=true>

We have introduced the following changes:


1)       Based on Brian's proposal to make the reporting even more efficient, Yanik analysed and designed a new way to encode bundle sequences which may contain some gaps (see updated Section 3.3). It is not so easy to come up with some concise language for that, so please let us know if you have suggestions for improvement.


2)       I took the opportunity to not allow processing of the CREB/CTEB blocks in fragments:

3.4.1          Extension Blocks specified in this specification shall only be added and processed in non-fragmented bundles.

NOTE - As later fragmentation of bundles using the extension blocks specified in this specification may lead to unintended effects such as loss of expected reporting or custody signals as fragmented bundles are never re-assembled (RfC 9171 does only specify Application Data Unit Re-Assembly), it is recommended to set the 'Bundle Must Not be Fragmented' flag at the source if the application of custody transfer or compressed status reporting according to this specification is intended.

3)       The compressed reporting signal (see 5.2.3) has been changed to include the reporting reason code as integer (and not as an integer interpreted as bit field). Please note that the Status Report Request Flags (5.1.4.1) shall actually be processed as a bit field. However, we align the Bit Number with the reason code integer for consistency.

Regards,
Felix

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