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 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.