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.