The Space Communications Protocol Specifications (SCPS) are a set of extensions to existing protocols and new protocols developed by the Consultative Committee for Space Data Systems (CCSDS) to improve performance of Internet protocols in space environments. The SCPS protocol stack consists of:

• SCPS-FP -- A set of extensions to FTP to make it more bit efficient and to add advanced features such as record update within a file and integrity checking on file transfers.
• SCPS-TP -- A set of TCP
  Transmission Control Protocol
  The Transmission Control Protocol is one of the core protocols of the Internet Protocol Suite. TCP is one of the two original components of the suite, complementing the Internet Protocol , and therefore the entire suite is commonly referred to as TCP/IP...
  
   options and sender-side modifications to improve TCP
  Transmission Control Protocol
  The Transmission Control Protocol is one of the core protocols of the Internet Protocol Suite. TCP is one of the two original components of the suite, complementing the Internet Protocol , and therefore the entire suite is commonly referred to as TCP/IP...
  
   performance in stressed environments including long delays, high bit error rates, and significant asymmetries. The SCPS-TP options are TCP options registered with the Internet Assigned Numbers Authority
  Internet Assigned Numbers Authority
  The Internet Assigned Numbers Authority is the entity that oversees global IP address allocation, autonomous system number allocation, root zone management in the Domain Name System , media types, and other Internet Protocol-related symbols and numbers...
  
   (IANA) and hence SCPS-TP is compatible with other well-behaved TCP
  Transmission Control Protocol
  The Transmission Control Protocol is one of the core protocols of the Internet Protocol Suite. TCP is one of the two original components of the suite, complementing the Internet Protocol , and therefore the entire suite is commonly referred to as TCP/IP...
  
   implementations.
• SCPS-SP -- A security protocol comparable to IPsec
  IPsec
  Internet Protocol Security is a protocol suite for securing Internet Protocol communications by authenticating and encrypting each IP packet of a communication session...
  
  
• SCPS-NP -- A bit-efficient network protocol analogous to but not interoperable with IP
  Internet Protocol
  The Internet Protocol is the principal communications protocol used for relaying datagrams across an internetwork using the Internet Protocol Suite...
  
  

The SCPS protocol that has seen the most use commercially is SCPS-TP, usually deployed as a Performance Enhancing Proxy

Performance Enhancing Proxy

Performance Enhancing Proxies are network agents designed to improve the end-to-end performance of some communications protocol. Performance Enhancing Proxies standards are defined in RFC 3135 and .-Classification:Available PEP implementations...

(PEP) to improve TCP performance over satellite links.

External links

• www.scps.org is a web page devoted to the SCPS protocols and contains links to the protocol specifications, briefing material, and test results.

• The Open Channel Foundation distributes a free reference implementation of the SCPS protocols that includes a transport-layer PEP application.
• CCSDS.org is the main web page for the CCSDS.