[CESG] Last Hop / First Hop service

Tomaso.deCola at dlr.de Tomaso.deCola at dlr.de
Tue May 30 15:00:41 UTC 2023

Hi Peter,

Thank you for providing the report from the SISG dated 2010! I was quite aware of that version but I had did not include the backup slides which also contain some relevant material.

In my opinion, the open points (=questions for CESG) are the following:

  1.  Is this ICPA requirement still meaningful or can it be superseded in favour of any new ones possibly coming from the Lunanet WG within IOAG?
  2.  If still requirement, which area shall lead the corresponding specification work ? According to what stated in the report, it would be about the definition of an delivery agent running on the higher protocol layers (e.g. in top of CFDP/SSI protocol stack) and the specification of the corresponding services

As to point 2), as already stated we see this not SIS-centric, as DTN is concerned here in terms of relaying capabilities but no more than that (at least according to the discussion had in the DTN WG). We are in any case happy to support the activity in whatever area is going to be carried out.

Best Regards,


Von: Shames, Peter M (US 312B) <peter.m.shames at jpl.nasa.gov>
Gesendet: Dienstag, 30. Mai 2023 10:05
An: de Cola, Tomaso <Tomaso.deCola at dlr.de>; CESG <cesg at mailman.ccsds.org>
Betreff: Last Hop / First Hop service

Dear Tomaso, et al,

During today’s CMC meeting the question came up of the origins of the Last Hop / First Hop service.  Regardless of which Area or WG takes this work up, I thought it worthwhile to share the document that defined this service, along with the rationale for it.

This was studied in 2010 as part of the IOAG Space Internetworking Strategy group (SISG).  It was intended as a service to “determine how the SSI will handle services for spacecraft that do not or cannot implement SSI user node functions”.  This explicitly includes SSI nodes that need to be “rebooted” using link layer / emergency commands, as well as nodes that are not DTN nodes, but that could benefit from using a higher speed DTN relay service than their own DTE/DFE link can support.

For the record, the attached document is what was published by the IOAG back in 2010.

Cheers, Peter

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.ccsds.org/pipermail/cesg/attachments/20230530/bf40dbc0/attachment.htm>

More information about the CESG mailing list