[Sis-dtn] New version of LTP Corrigendum

Thu May 25 11:56:23 UTC 2023

Hi,

I agree with the modifications below.

Some additional points:

  *   I would propose to also deprecate Service Data Aggregation (it is currently mandatory). Unless, I am overlooking something, it is not an interoperable mechanism as there is no generic way to determine the length of a client data capsule. Also, for BP/LTP the updated BP standard will describe an aggregation mechanism (CBOR length information + bundle IIRC).
  *   Should we discourage use of mixed sessions (on the other hand LTP green is optional anyway)?
  *   For the two additional issues, we could add that this is an implementation issue and that implementation may want to introduce these additional timers in case they (routinely) expect out-of-order delivery

Regards,
Felix

From: SIS-DTN <sis-dtn-bounces at mailman.ccsds.org> On Behalf Of sburleig.sb--- via SIS-DTN
Sent: Thursday, May 18, 2023 1:23 AM
To: 'Sanchez Net, Marc (US 332H)' <marc.sanchez.net at jpl.nasa.gov>; 'Dr. Keith L Scott via SIS-DTN' <sis-dtn at mailman.ccsds.org>
Cc: 'Torgerson, J. Leigh (US 332C)' <jordan.l.torgerson at jpl.nasa.gov>
Subject: Re: [Sis-dtn] New version of LTP Corrigendum

Marc, FWIW, I agree about deprecating LTP security and I am likewise skeptical that adding more timers is a good idea; that sounds like a way to work around a design element that hasn't been thought through completely.

Scott

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: Tuesday, May 16, 2023 7:05 PM
To: Dr. Keith L Scott via SIS-DTN <sis-dtn at mailman.ccsds.org<mailto:sis-dtn at mailman.ccsds.org>>
Cc: Torgerson, J. Leigh (US 332C) <jordan.l.torgerson at jpl.nasa.gov<mailto:jordan.l.torgerson at jpl.nasa.gov>>
Subject: [Sis-dtn] New version of LTP Corrigendum

All,

Please find attached a new version of the LTP corrigendum with some modifications including:
*         Comparison between LTP and "the new protocol" has been reduced. This in part motivated by the fact that we have demonstrated ~4 Gbps rates with ION's LTP implementation, which is more than sufficient for deep space links (e.g., even in future trunk lines between Earth and Mars, data rates of 4 Gbps are never exceeded).
*         I have added two possible additions to the technical corrigendum based on work done by Brian and people at GRC. They are all optional (MAY) statements and I believe can be implemented without additional managed parameters (and timers).
*         Brian has commented on two additional issues (see here<https://github.com/nasa/HDTN/issues/22> and here<https://github.com/nasa/HDTN/issues/24>), but those seem to require additional timers that would need to be managed, so I am unconvinced it is worth the extra complexity. Brian, please correct me if I am wrong.
Finally, I think the note at the beginning of Section 3.9 of the current CCSDS LTP spec should be modified to explicitly state that LTP security should not be used and, instead, implementers should rely on security mechanisms provided by other parts of the CCSDS protocol stack, be it SDLS or BPSec. Thoughts on this point?

[https://opengraph.githubassets.com/20650d8341084e048ce0b347834a0c8d441c40acab81b1ef4c075e8770078d33/nasa/HDTN/issues/24]<https://github.com/nasa/HDTN/issues/24>
Defer data retransmission with out-of-order report segments * Issue #24 * nasa/HDTN<https://github.com/nasa/HDTN/issues/24>
When the network is causing out-of-order segment reception it is possible that one or more synchronous reception reports are received either out-of-order or within a short time window, possibly fol...
github.com
[https://opengraph.githubassets.com/557790465f865a493213b66289d08ffd17c4b98d48ae91ec6ef62866fa1ceac9/nasa/HDTN/issues/22]<https://github.com/nasa/HDTN/issues/22>
Defer synchronous reception report with out-of-order data segments * Issue #22 * nasa/HDTN<https://github.com/nasa/HDTN/issues/22>
When red part data is segmented and delivered to the receiving engine out-of-order, the checkpoint(s) and EORP can be received before the earlier-in-block data segments. If a synchronous report is ...
github.com

Thanks,
-----------------------------------------------------------------------------------------------------------------------
Marc Sanchez Net (332H)
Telecommunications Engineer
Jet Propulsion Laboratory
Cell: (617) 953-7977<mailto:(617)%20953-7977> | Email: marc.sanchez.net at jpl.nasa.gov<mailto:marc.sanchez.net at jpl.nasa.gov>
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