The CCSDS (Consultative Committee for Space Data Systems) File Delivery Protocol for Interplanetary Overlay Network (CFDP-ION) is an implementation of CFDP that uses ION’s DTN (delay tolerant networking) implementation as its UT (unit-data transfer) layer. Because the DTN protocols effect automatic, reliable transmission via multiple relays, CFDP-ION need only satisfy the requirements for Class 1 (“unacknowledged”) CFDP. This keeps the implementation small, but without loss of capability.
This innovation minimizes processing resources by using zero-copy objects for file data transmission. It runs without modification in VxWorks, Linux, Solaris, and OS/X. As such, this innovation can be used without modification in both flight and ground systems. Integration with DTN enables the CFDP implementation itself to be very simple; therefore, very small. Use of ION infrastructure minimizes consumption of storage and processing resources while maximizing safety.
This work was done by Scott C. Burleigh of Caltech for NASA’s Jet Propulsion Laboratory.
The software used in this innovation is available for commercial licensing. Please contact Daniel Broderick of the California Institute of Technology at
This Brief includes a Technical Support Package (TSP).
CFDP for Interplanetary Overlay Network
(reference NPO-47084) is currently available for download from the TSP library.
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Overview
The document outlines the CCSDS File Delivery Protocol (CFDP) for the Interplanetary Overlay Network (ION), developed by NASA's Jet Propulsion Laboratory. CFDP is an international standard designed for automatic, delay-tolerant, and reliable file transfer, particularly suited for space communications. It supports concurrent file transfers in both directions, ensuring data is delivered in the correct order without waiting for missing segments, and allows for the preliminary delivery of individual records before the complete file is received.
CFDP operates symmetrically, meaning that the communication process is the same regardless of which entity is sending or receiving data. It includes mechanisms for data integrity, such as mandatory file checksums and optional cyclic redundancy checks (CRCs) on individual records. The protocol relies on the Unitdata Transfer (UT) layer for actual data transmission, which can vary in capability across four defined classes of service, from best-effort delivery to automated retransmission procedures.
CFDP-ION specifically utilizes the ION's Delay-Tolerant Networking (DTN) protocols, which facilitate reliable communication over complex network topologies, including deep-space links. This implementation allows CFDP-ION to operate under Class 1 requirements, focusing on unacknowledged data transmission. It segments files according to user-defined rules, transmits these segments, and reassembles them at the receiving end, all while managing user-supplied metadata.
The CFDP-ION system is designed for both flight and ground applications, minimizing software acquisition and support costs. It features capabilities for canceling, suspending, resuming, and monitoring file transmissions, as well as reporting on transmission and reception activities. The protocol data units are encapsulated as application data within DTN bundles, which can be routed through multiple ground stations and relay orbiters, optimizing communication resources and reducing latency.
Overall, the document emphasizes the importance of CFDP in enhancing data transfer reliability in space missions, showcasing its adaptability to various operating systems and its integration with the ION infrastructure. This technology is crucial for future space exploration and communication, ensuring that data can be transmitted efficiently across vast distances.
