[Sis-dtn] [EXTERNAL] Re: [EXT] RE: LTP vs LTPv2

Mon Oct 11 14:12:00 UTC 2021

Peter,

I think the real issue at hand is whether or not to maintain the LTPv1 spec as Blue once LTPv2 is published.

My interpretation of Leigh’s argument is that vendors are currently implementing to LTPv1 (and the current BPv6-based BP for CCSDS Book) and that deprecating those specs in favor of new, non-backward-compatible ones would be looked upon unfavorably.

                                v/r,

                                --keith

From: Tomaso.deCola at dlr.de <Tomaso.deCola at dlr.de>
Date: Monday, October 11, 2021 at 3:11 AM
To: peter.m.shames at jpl.nasa.gov <peter.m.shames at jpl.nasa.gov>
Cc: Dr. Keith L Scott <kscott at mitre.org>, Gifford, Kevin <kevin.gifford at colorado.edu>, marc.sanchez.net at jpl.nasa.gov <marc.sanchez.net at jpl.nasa.gov>, sis-dtn at mailman.ccsds.org <sis-dtn at mailman.ccsds.org>
Subject: RE: [EXTERNAL] Re: [EXT] RE: LTP vs LTPv2
Dear Peter,

Thank you for your kind support and availability for helping us in finding a suitable solution.
Indeed the two options you have mentioned are also those we have put on the table as possible solutions, although both of them show pros and cons and therefore compromise and agreement/consensus between the parties will have to be reached. This discussion will keep on going during the next DTN telco as well as the official CCSDS DTN WG Fall meetings in order to reach soon an agreed approach as also mentioned by Keith in a previous e-mail. In case no solution will be agreed, then I’ll certainly bring this point in the SIS area summary at the CESG meeting in November in order to find a way out for this impasse. Obviously, I’ll certainly count on your and other CESG colleagues suggestions to move forward and more importantly to avoid any postponed decision that would be detrimental to the activities of the DTN WG.

Best Regards
Tomaso

From: Shames, Peter M (US 312B) <peter.m.shames at jpl.nasa.gov>
Sent: Samstag, 9. Oktober 2021 01:26
To: Kevin K Gifford <kevin.gifford at colorado.edu>; Dr. Keith L Scott <kscott at mitre.org>; Cola, Tomaso de <Tomaso.deCola at dlr.de>; Sanchez Net, Marc (US 332H) <marc.sanchez.net at jpl.nasa.gov>
Cc: sis-dtn at mailman.ccsds.org
Subject: Re: [EXTERNAL] Re: [EXT] RE: LTP vs LTPv2

Guys,

As a long term member of the CESG I do agree that you can kick it “upstairs” to the CESG and have, I believe, a hope of getting a sensible response (most of the time).  Heck, we are human and therefore fallible.

>From my own point of view I recommend doing two things:

  1.  As I understand it, they are different protocols, hence not “backward compatible”.  Using the “version” option, including, in this case, adopting some explicit name extension like LTPv2 makes the most sense to me.  The rationale for that is that what you plan to produce is not backward compatible with v1.  In other words, there is no way to configure V2, without the new options, and still have a v1 implementation accept it.
  2.  Silverize the v1 book.  This is normally done when a new protocol version is created.  The old silver book will still be available and it may be referenced with its (new) silver name and number.  This has happened before with other specs.  It is not unusual for some mission to nail their interface to some specific version of a document, even, in some cases, a Red Book (which is really dangerous since they are likely to change).

If you want to discuss this further please let me know.  And it you do decide to send it to the CESG you now know where I stand, and why.  Of course, if any of my assumptions are flawed I am happy to be corrected.

Cheers, Peter

From: Kevin K Gifford <kevin.gifford at colorado.edu<mailto:kevin.gifford at colorado.edu>>
Date: Friday, October 8, 2021 at 11:58 AM
To: Keith Scott <kscott at mitre.org<mailto:kscott at mitre.org>>, "Tomaso.deCola at dlr.de<mailto:Tomaso.deCola at dlr.de>" <Tomaso.deCola at dlr.de<mailto:Tomaso.deCola at dlr.de>>, Marc Sanchez Net <marc.sanchez.net at jpl.nasa.gov<mailto:marc.sanchez.net at jpl.nasa.gov>>
Cc: "sis-dtn at mailman.ccsds.org<mailto:sis-dtn at mailman.ccsds.org>" <sis-dtn at mailman.ccsds.org<mailto:sis-dtn at mailman.ccsds.org>>, Peter Shames <peter.m.shames at jpl.nasa.gov<mailto:peter.m.shames at jpl.nasa.gov>>, Kevin K Gifford <kevin.gifford at colorado.edu<mailto:kevin.gifford at colorado.edu>>
Subject: [EXTERNAL] Re: [EXT] RE: LTP vs LTPv2

Hi SIS-DTN -

FWIW, I want to emphasize that the CESG does a great job in this regard (fixing issues that arise in WGs or inter-WG conflicts or inter-agency conflicts).
-- Keith was a member of the CESG for several years and understands this vital role that the CESG plays in issues such as this

Thus, my two cents worth is await CESG advice as well as Keith already stated (I wanted to maybe ease any queasiness in regard to CESG involvement/inputs).

Thanks.

Kevin
________________________________
From: SIS-DTN <sis-dtn-bounces at mailman.ccsds.org<mailto:sis-dtn-bounces at mailman.ccsds.org>> on behalf of Dr. Keith L Scott <kscott at mitre.org<mailto:kscott at mitre.org>>
Sent: Friday, October 8, 2021 12:49 PM
To: Tomaso.deCola at dlr.de<mailto:Tomaso.deCola at dlr.de> <Tomaso.deCola at dlr.de<mailto:Tomaso.deCola at dlr.de>>; marc.sanchez.net at jpl.nasa.gov<mailto:marc.sanchez.net at jpl.nasa.gov> <marc.sanchez.net at jpl.nasa.gov<mailto:marc.sanchez.net at jpl.nasa.gov>>
Cc: sis-dtn at mailman.ccsds.org<mailto:sis-dtn at mailman.ccsds.org> <sis-dtn at mailman.ccsds.org<mailto:sis-dtn at mailman.ccsds.org>>
Subject: Re: [Sis-dtn] [EXT] RE: LTP vs LTPv2

OK fine, if the CESG decides to not rule on it, great, we’ll make a decision in the WG and they can live with it (and we can certainly discuss it SOME in the WG; don’t want to put too much time into it until the CESG is at least given a chance to get us out of this).

                                --keith

From: Tomaso.deCola at dlr.de<mailto:Tomaso.deCola at dlr.de> <Tomaso.deCola at dlr.de<mailto:Tomaso.deCola at dlr.de>>
Date: Friday, October 8, 2021 at 10:04 AM
To: Dr. Keith L Scott <kscott at mitre.org<mailto:kscott at mitre.org>>, marc.sanchez.net at jpl.nasa.gov<mailto:marc.sanchez.net at jpl.nasa.gov> <marc.sanchez.net at jpl.nasa.gov<mailto:marc.sanchez.net at jpl.nasa.gov>>
Cc: sis-dtn at mailman.ccsds.org<mailto:sis-dtn at mailman.ccsds.org> <sis-dtn at mailman.ccsds.org<mailto:sis-dtn at mailman.ccsds.org>>
Subject: RE: [EXT] RE: LTP vs LTPv2

Hi Keith,

I agree with your point on troubles in maintaining two books and the fact that this will imply the same treatment for BPv7. Then whether agencies are happy to refer to a silver book rather than a blue book is a bit question mark in my opinion. I remember we decided a few years ago not to silverize SCPS-TP exactly because there were activities or usage of the corresponding blue book.

We can certainly bring this matter to the next CESG meeting, although I fear that there might be no strict decision in this regard, since I think there is no specific rule again either approaches and the hot potato could be sent back to WG.

Regards,

Tomaso

From: Dr. Keith L Scott <kscott at mitre.org<mailto:kscott at mitre.org>>
Sent: Freitag, 8. Oktober 2021 15:52
To: Cola, Tomaso de <Tomaso.deCola at dlr.de<mailto:Tomaso.deCola at dlr.de>>; marc.sanchez.net at jpl.nasa.gov<mailto:marc.sanchez.net at jpl.nasa.gov>
Cc: sis-dtn at mailman.ccsds.org<mailto:sis-dtn at mailman.ccsds.org>
Subject: Re: [EXT] RE: LTP vs LTPv2

I don’t like it, but I propose that the WG move forward with developing the book and you bring up the new-version vs. new-book issue to the CESG.

Reasons I don’t like the two-book solution:

  *   So now we’re maintaining two versions of LTP, which version are folks supposed to choose for missions going forward?  They’ll choose the one with flight heritage, right?
  *   We’ll have to do the same thing with BPv7
  *   There’s a version number in the header; receivers will know what was sent.
  *   The book as Silver is still reference-able.  If folks have systems they’re building to the current (v1) book, they can switch to referencing the silver book.
  *   Why don’t we do that with ALL CCSDS books, backward-compatible or not?

--keith

From: Tomaso.deCola at dlr.de<mailto:Tomaso.deCola at dlr.de> <Tomaso.deCola at dlr.de<mailto:Tomaso.deCola at dlr.de>>
Date: Friday, October 8, 2021 at 4:19 AM
To: marc.sanchez.net at jpl.nasa.gov<mailto:marc.sanchez.net at jpl.nasa.gov> <marc.sanchez.net at jpl.nasa.gov<mailto:marc.sanchez.net at jpl.nasa.gov>>, Dr. Keith L Scott <kscott at mitre.org<mailto:kscott at mitre.org>>
Cc: sis-dtn at mailman.ccsds.org<mailto:sis-dtn at mailman.ccsds.org> <sis-dtn at mailman.ccsds.org<mailto:sis-dtn at mailman.ccsds.org>>
Subject: [EXT] RE: LTP vs LTPv2

Then probably we should better keep two books, one with the “old LTP” for which we’ll do some pink sheets to fix some inconsistencies and another one (the new LTP). In such a away we could have two versions of LTP available, similarly to IPv4 and IPv6 in IETF. Probably we may have to slightly change the title of the books (v1 and v2?) to have a clear demarcation between the two version of the protocols and avoid any ambiguity.

@Scott, Keith L.<mailto:kscott at mitre.org>:what do you think?

Tomaso

From: SIS-DTN <sis-dtn-bounces at mailman.ccsds.org<mailto:sis-dtn-bounces at mailman.ccsds.org>> On Behalf Of Sanchez Net, Marc (US 332H) via SIS-DTN
Sent: Donnerstag, 7. Oktober 2021 00:21
To: sis-dtn at mailman.ccsds.org<mailto:sis-dtn at mailman.ccsds.org>
Subject: [Sis-dtn] LTP vs LTPv2

All,

I had to leave today’s meeting early. Did we reach consensus on how to proceed?

Also, I will note that some colleagues at JPL (I have similar concerns) do not really like the idea of turning the current version of LTP into a silver book. The problem is that, by definition, a silver book implies that a protocol is deprecated or obsolete, but several systems that are being built today use BPv6+LTP or BPv7+LTP and thus might be in operation for a long time. So, essentially, we are “telling” industry that they have developed an already obsolete standard?

Best,

-----------------------------------------------------------------------------------------------------------------------

Marc Sanchez Net

Telecommunications Engineer

Jet Propulsion Laboratory

Office: (818) 354-1650<tel:(818)%20393-5840> | Email: marc.sanchez.net at jpl.nasa.gov<mailto:marc.sanchez.net at jpl.nasa.gov>

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