[Sis-dtn] Compressed Bundle Status Reporting and Custody Signalling - Orange Book Draft

Thu Apr 3 15:43:20 UTC 2025

Thanks a lot Brian,

We certainly can add some text regarding the sequence number scope. It could be simply 'sequence scope' but I am open for any other suggestions and would be happy to align.

We will also look into you 2nd suggestion and might change accordingly.

Regards,
Felix

From: Sipos, Brian J. <Brian.Sipos at jhuapl.edu>
Sent: 28 March 2025 17:31
To: Felix Flentge <Felix.Flentge at esa.int>
Cc: sis-dtn at mailman.ccsds.org; Taylor, Rick <rick.taylor at airbus.com>
Subject: RE: Compressed Bundle Status Reporting and Custody Signalling - Orange Book Draft
Importance: High

Felix,
I think the overall descriptions and technical contents are cohesive and consistent.

There is one aspect that I think can use more up-front clarification: a high-level description for the "scope" of the sequence number. It looks like there is a placeholder for this in Section 2.1 and some description in Section 3.1, but there is not a clear name for the "scope" or "channel" in which a sequence number is unique and used by receivers to correlate them together for "signal" messages.
>From my reading the scope is a combination of:

1.       The administrative EID of the originator of the sequence number (whether implicit or explicitly encoded)

2.       One of:

o   A single destination EID, or

o   An explicit Sequence ID itself scoped to the administrative EID from (1) above
I don't think the technical definitions for the use of this scope is missing or inconsistent, there just doesn't appear to be a higher-up summary like the short list above to frame the technical requirements and explain how the two entities involved ensure uniqueness and proper correlation of the sequence number values. I'm copying Rick Taylor on this message because having a name for this well-defined scope of unique numbers is also something that the BPT-U draft also needs (for very different purposes) but it would be good if the terminology was consistent.

The other thing is more technical in Section 3.3: the current Bundle Sequence contains a single pair of "First Sequence Number" and "Length" for each contiguous block of numbers being reported. In the case there are multiple contiguous blocks being reported on this will result in some compressible redundancy in the overall Sequence Collection. I think this is fine for an orange book, discussing what is actually implemented and tested, but it is possible to compress this case and I suggest using a list-of-pairs encoding used in the "range" construct used as part of Section 2.4.4 of the EID Patterns draft [1] but excluding the open-ended last length. That construct is usable for a compressed encoding of any ordered-set-of-finite-integer-intervals. It also degenerates to exactly the form you currently have in the draft orange book when there is only a single interval, so it isn't a large stretch from what is currently implemented.

Thanks for consideration,
Brian S.

[1] https://www.ietf.org/archive/id/draft-ietf-dtn-eid-pattern-01.html#section-2.4.4-4

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: Thursday, March 20, 2025 11:25 AM
To: Dr. Keith L Scott via SIS-DTN <sis-dtn at mailman.ccsds.org<mailto:sis-dtn at mailman.ccsds.org>>
Subject: [EXT] [Sis-dtn] Compressed Bundle Status Reporting and Custody Signalling - Orange Book Draft

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Hi,

I have uploaded the latest draft of the Compressed Bundle Status Reporting and Custody Signalling - Orange Book to CWE

https://spacecomm.sharepoint.com/:w:/r/sites/SIS/Shared%20Documents/SIS-DTN/Draft%20Documents/Compressed%20Bundle%20Reporting/CompressedBundleStatusReportingAndCustodySignaling_OrangeBook_Draft_G.docx?d=w0dad34d3ccdf4d55bf5239ef446a99c3&csf=1&web=1

This draft should be complete in terms of technical specification (but missing some of the non-normative sections).

I would welcome a (final) review by the DTN WG in terms of technical content (and also appreciate help/suggestion for the non-normative sections).

Regards,
Felix

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