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

Fri Mar 28 16:30:41 UTC 2025

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:

*	A single destination EID, or
*	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> 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>
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/CompressedBundleStatusRep
ortingAndCustodySignaling_OrangeBook_Draft_G.docx?d=w0dad34d3ccdf4d55bf5239e
f446a99c3&csf=1&web=1>
https://spacecomm.sharepoint.com/:w:/r/sites/SIS/Shared%20Documents/SIS-DTN/
Draft%20Documents/Compressed%20Bundle%20Reporting/CompressedBundleStatusRepo
rtingAndCustodySignaling_OrangeBook_Draft_G.docx?d=w0dad34d3ccdf4d55bf5239ef
446a99c3&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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