[Sls-slp] Results of Discussion with Takahiro Yamada on Revising SPP Blue Book
Shames, Peter M (312B)
peter.m.shames at jpl.nasa.gov
Mon Jan 29 19:20:07 UTC 2018
I think John is right. The distinction is between a “Space Packet Service “ that is a data encapsulation and multiplexing service within some “subnet” and a Packet Transfer Service that is the way Space Packets are transferred over an SDL. This does include the SPP muxing into an SDL VC. SPP itself cannot assert responsibility for this since it has only virtual (or managed) knowledge of how the packets will be transferred over the subnet.
Sent from Peter's JPL iPhone 7
Everything should be made as simple as possible,
but not simpler.
On Jan 27, 2018, at 11:00 AM, "Gian.Paolo.Calzolari at esa.int<mailto:Gian.Paolo.Calzolari at esa.int>" <Gian.Paolo.Calzolari at esa.int<mailto:Gian.Paolo.Calzolari at esa.int>> wrote:
Good hint, John.
It looks as we shall carry out a good comparison of the the homonymous services and determine the real deltas. It may be that in SPP only a Space Packet Multiplexing is required.
Sent from my iPhone
On 27. Jan 2018, at 16:21, John Pietras <john.pietras at gst.com<mailto:john.pietras at gst.com>> wrote:
Members of the SLPWG,
I have read through Greg’s summary of his conversation with Takahiro regarding suggested simplifications of the SPP book. One of those suggested changes is the removal of the Packet Service, which the memo implied was redundant with this Packet Service provided by the Space Data Link Protocols. This is not quite true – the Packet Service that is provided by the SPP provides the additional functionality of muxing/demuxing Packets with different APIDs into/out of a single VC.
Admittedly, I have been away from the day-to-day considerations of space link protocols for many years, but having been a member of the Panel 1 F/G team that wrote the original AOS Blue Book I can attest to the fact that the ability to flow multiple “packet channels” through a single VC was an important aspect of the protocol stack, at least at the time (late 80s). Unless there is no longer a perceived need to do such packet channel muxing/demuxing, such a capability would have to be retained in the SPP book or re-integrated into the various SDLP books as appropriate.
I will agree that calling both the SPP “Packet Services” and the SLDP “Packet Services” by the same name is confusing and can lead to overlooking this additional functionality of the SPP flavor of the service. Perhaps a different name to distinguish them would be useful.
From: SLS-SLP [mailto:sls-slp-bounces at mailman.ccsds.org] On Behalf Of Kazz, Greg J (312B)
Sent: Thursday, January 25, 2018 5:41 PM
To: sls-slp at mailman.ccsds.org<mailto:sls-slp at mailman.ccsds.org>
Subject: [Sls-slp] Results of Discussion with Takahiro Yamada on Revising SPP Blue Book
Dear SLP WG,
Happy New Year 2018 !
This topic concerns the new project recently approved for revising the Space Packet Protocol (SPP) Blue book.
Please read the attached Word file that contains a discussion I had with Takahiro Yamada, the driving force in the CCSDS restructuring of the Packet Telemetry Blue Book. Parts of that book under Takahiro’s guidance became the Space Packet Protocol, SPP, which we are now tasked to revise and update.
I have made several suggestions about removing sections of the existing SPP document and I have asked Takahiro to give us his opinion about it.
I would like to hold a 1 hour telecon on this subject in the very near future. I will set up a doodle poll to determine when the best time will be to discuss this topic. Please look forward to the invitation. If you don’t see one, please let me know so that I can add you to the list, if I missed you.
CCSDS SLP WG Chairman
Technical Group Supervisor,
Project Software and End-to-End Information Systems Engineering (312B)
Jet Propulsion Laboratory
4800 Oak Grove Dr., M/S 301-490
Pasadena, CA 91109
email: greg.j.kazz at jpl.nasa.gov<mailto:greg.j.kazz at jpl.nasa.gov>
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