The CCSDS File Delivery Protocol (CFDP-reference [1]) has been designed to support the transfer of files in a variety of mission scenarios. CFDP offers different qualities of service ranging from best effort to fully reliable and has been specifically optimized for long delay, noisy, and disjoint links. CFDP requires a simple minimum service from the underlying protocols, operating over any link providing a packet communication service.

ISO 20105:2015 is to specify how to operate CFDP over the CCSDS Encapsulation Service (reference [2]) as provided for Earth-to-spacecraft, spacecraft-to-Earth, and spacecraft-to-spacecraft communications. It sets out the communications architecture for CFDP operating over the Encapsulation Service. It describes the service expected by CFDP of the underlying layers and reconciles this with the service provided by the Encapsulation Service.