International Telemetering Conference Proceedings / October 18-21, 2004 / Town & Country Resort, San Diego, California / The CCSDS has developed the “CCSDS File Delivery Protocol” (CFDP), as a disruption/delay tolerant file transfer protocol. CFDP allows an automatic, reliable file transfer between spacecraft and ground (in both directions) designed to support the operation of spacecraft by means of file transfer and remote file system management. To support the development and fielding of the protocol in an international and cross-supporting environment, an international, inter-operability test program has been developed and successfully executed. First phase testing involved five independent implementations of the Core Procedures of the protocol. The second phase tests involve multi-hop transferring of files using the Extended Procedures. The third phase involves the testing of the SFO Procedures. The latter two phases involved two independent protocol implementations, namely, those of ESA and JPL. This paper constitutes a final report on the process of testing, the test results, the experience gained, and the resulting plans to extend this methodology to other areas within the CCSDS.

International Telemetering Conference Proceedings / October 22-25, 2001 / Riviera Hotel and Convention Center, Las Vegas, Nevada / In CCSDS File Delivery Protocol (CFDP), four acknowledged modes essentially have an identical protocol for initializing and closing a file delivery. In this protocol, the system occasionally run into a state in which Sender has closed the transaction and Receiver has not closed the transaction. In this paper, we point out the danger of such state being prolonged. Such a state can be prolonged due to link occultation, extremely long propagation delay, or implementation caused by common misinterpretation of the protocol specification. We provide two failure scenarios, which occur in such a state. Then, we discuss ways of preventing such failures.

International Telemetering Conference Proceedings / October 18-21, 2004 / Town & Country Resort, San Diego, California / The Consultative Committee for Space Data Systems (CCSDS) developed the CCSDS File Delivery Protocol (CFDP) to provide reliable delivery of files across space links. Space links are typically intermittent, requiring flexibility on the part of CFDP. Some aspects of that flexibility will be highlighted in this paper, which discusses the planned use of CFDP on the Global Precipitation Measurement (GPM) mission. The operational scenario for GPM involves reliable downlink of science data files at a high datarate (approximately 4 megabits per second) over a space link that is not only intermittent, but also one-way most of the time. This paper will describe how that scenario is easily handled by CFDP, despite the fact that reliable delivery requires a feedback loop.

International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Reliable delivery of data products is often required across space links. For example, a NASA mission will require reliable delivery of images produced by an on-board detector. Many missions have their own (unique) way of accomplishing this, requiring custom software. Many missions also require manual operations (e.g. the telemetry receiver software keeps track of what data is missing, and a person manually inputs the appropriate commands to request retransmissions). The Consultative Committee for Space Data Systems (CCSDS) developed the CCSDS File Delivery Protocol (CFDP) specifically for this situation. CFDP is an international standard communication protocol that provides reliable delivery of data products. It is designed for use across space links. It will work well if run over the widely used CCSDS Telemetry and Telecommand protocols. However, it can be run over any protocol, and will work well as long as the underlying protocol delivers a reasonable portion of the data. The CFDP receiver will autonomously determine what data is missing, and request retransmissions as needed. The CFDP sender will autonomously perform the requested transmissions. When the entire data product is delivered, the CFDP receiver will let the CFDP sender know that the transaction has completed successfully. The result is that custom software becomes standard, and manual operations become autonomous. This paper will consider various ways of achieving reliable file delivery, explain why CFDP is the optimal choice for use over space links, explain how the core protocol works, and give some guidance on how to best utilize CFDP within various mission scenarios. It will also touch on additional features of CFDP, as well as other uses for CFDP (e.g. the loading of on-board memory and tables).

International Telemetering Conference Proceedings / October 18-21, 2004 / Town & Country Resort, San Diego, California / The MESSENGER mission to Mercury will downlink data files via a protocol defined by the Consultative Committee for Space Data Systems (CCSDS) called the CCSDS File Delivery Protocol (CFDP). A reduced implementation of the protocol was developed for the spacecraft due to various system constraints and operational requirements. The software operates in conjunction with the playback features of the MESSENGER flight software allowing for the autonomous downlinking of files as well as providing for the management of the file system by the mission operations team. This paper presents the software implementation, metrics, and the lessons learned.

International Telemetering Conference Proceedings / October 22-25, 2001 / Riviera Hotel and Convention Center, Las Vegas, Nevada / We study the reliable (acknowledged) operation (i.e., ARQ scheme) of CFDP (CCSDS File Delivery Protocol) over single-hop space link. We focus on the immediate NAK mode, as specified in [1], under the assumption that PDU error events of forward and backward channels are statistically independent. We point out the problem of duplicated retransmissions due to the long propagation delay and analyze throughput efficiency. We also present modeling and analysis of the average time taken for the delivery of a file with an arbitrary size, which are more rigorous than currently available heuristics.

International Telemetering Conference Proceedings / October 22-25, 2001 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The Consultative Committee for Space Data Systems (CCSDS) is defining a CCSDS File Delivery Protocol (CFDP) capable of use between systems of multiple endpoints. A number of prototype CFDP implementations have been developed and some interoperability tests performed over UDP links. This paper reports on a study of CFDP running over more realistic packet telecommand and packet telemetry links. An integrated test system was constructed by adapting existing commercial and prototype software. This was used to study a number of scenarios which are likely to be important in early operational use of CFDP in space. This approach has been found to be useful both for testing a protocol during its development and specification and for verifying the impact of new approaches to Space Missions.

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