The four Space Communications Protocol Specification (SCPS) Recommendations define a protocol suite that is parallel in function to, and interoperable with, the protocols of the Earth-based Internet (FTP/TCP/IP). The SCPS protocols have been optimized to overcome problems associated with using Internet protocols in space. This Recommendation defines the transport-layer protocols and services of the SCPS protocol suite. The current issue of Space Communications Protocol Specification (SCPS) Transport Protocol (SCPS-TP) specification: - adds optional support for Selective Acknowledgements (SACK) and Explicit Congestion Notification (ECN)- defines semantics to extend SCPS-TP signaling to allow optional inclusion of vendor- and community-specific options. The CCSDS conducts periodic reconfirmation reviews of its publications to assure their continued relevance.

This Recommended Standard has been reconfirmed through June 2022.