Name of Group | 6.12 CFDP Revisions Working Group |
Area | Space Internetworking Services Area (SIS) |
Chairperson | Felix Flentge |
Chairperson E-Mail Address | felix.flentge@esa.int |
Chairperson Agency | ESA |
Deputy Chairperson | Dai Stanton |
Deputy Chairperson E-Mail Address | dstanton@keltik.co.uk |
Deputy Chairperson Agency | UKSA |
Mailing List | Sis-cfdpv1@mailman.ccsds.org |
Scope of Activity | The working group will accomplish the mandated 5-year reconfirmation review of the CCSDS File Delivery Protocol (CFDP) Blue Book. To this end, the working group will consider a number of proposed revisions to CFDP (listed below) and thereupon apply to the specification some agreed-upon subset of those revisions; will perform interoperability testing between two independently developed implementations of the changes incorporated into the revised CFDP Blue Book, to ensure that the revised specification can be successfully implemented; and will revise the three CFDP Green Books accordingly.
The following CFDP revisions have been proposed:
• Remove the Extended Procedures, which are unused.
• Relocate the Store and Forward Overlay User Operation (SFO) to a normative annex. (This could be a step toward eventually deprecating SFO in favor of operating CFDP over a Bundle Protocol unitdata transfer layer.)
• Provide a way of using CFDP to transfer files that are larger than 4 GB.
• Increase the maximum file data segment size, to reduce per-segment processing overhead.
• Add per-segment metadata to increase the utility of individually received file data segments prior to reassembly of an entire file.
• Enable file record boundaries to be encoded in file data segments, so that a record may span multiple segments or multiple records may be aggregated into a single segment.
• Define additional standard service classes that include different subsets of CFDP functionality.
• Add more Delivery Code values to make the Finished PDU more informative in proxy operations.
• Add the ability to aggregate the Finished information for multiple transactions into a single segment.
• Standardize the format for listing the contents of a remote directory.
In developing the agreed-upon revisions the working group will preserve backward compatibility with existing CFDP implementations to the extent possible.
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Rationale for Activity | Publication CCSDS A02.1-Y-3, CCSDS Organization and Processes, requires that
Recommended Standards undergo reconfirmation review every five years; the current release of the CFDP specification (CCSDS 727.0-B-4) was published in January of 2007. Moreover, a number of revisions to CFDP have been proposed with the intent of making the specification more suitable for current and future space flight missions including the NASA Mars program and operations on the International Space Station.
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Goals | The goals of the CFDP Revisions Working Group are:
• Publish a new version of the CFDP Blue Book, incorporating an agreed-upon subset of the revisions proposed in the “Scope of Activity” above.
•As part of the Blue Book activity, document the results of interoperability testing of the revised CFDP Blue Book.
• Publish revised editions of the three CFDP Green Books, aligning them with the revised CFDP Blue Book.
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Survey of Similar Standards Efforts Undertaken in
Other Bodies and elsewhere in CCSDS | Pink sheets for one CFDP revision – providing for the transmission of a “Finished” PDU on completion of a file transfer transaction in Unacknowledged mode – are being developed within the SIS Delay-Tolerant Networking Working Group. Development of this revision has been migrated into the proposed scope of work of the CFDP Revisions Working Group. No other revisions to CFDP, nor development of alternative space flight file transfer protocol specifications, are in progress elsewhere within CCSDS or within other known standards bodies. |
Patent Licensing Applicability for Future Standards | There are NO known patent license issues. |
Technical Risk Mitigation Strategy | The participating agencies were involved in the original development of CFDP and in its implementation. Their familiarity with the issues minimizes the likelihood of failure in developing the proposed revisions. |
Management Risk Mitigation Strategy | Resource estimates provided by the participating agencies ensure that sufficient technical resources will be applied to enable the CFDP Revisions Working Group to meet its goals. |
