Network Acceleration (incl. SCPS-TP)

Space Communications Protocol Specifications (SCPS) are a set of protocols and extensions to existing protocols created to adapt IP communications to the unique environment of space.

These updated protocols are designed to improve reliability, error checking, efficiency and performance in communications between ground locations, manned craft and satellites.

TCP PEP (TCP Performance Enhancing Proxy)

This industry standard for TCP acceleration over high latency links is designed to overcome the impact of latency on the throughput of satellite and other impaired links. The SCPS-TP options are TCP options registered with the Internet Assigned Numbers Authority (IANA) and hence SCPS-TP is compatible with other well-behaved TCP implementations.

The OPUS Enhance TCP Acceleration function provides an interoperable standards based SCPS-TP capability as defined in the Consultative Committee for Space Data Systems (CCSDS) Recommended Standard CCSDS 714.0-B-2 Blue Book October 2006 found at

Standalone, SCPS has its benefits, but combined with PACE+ and other capabilities in OPUS Enhance, it brings superior performance to a wide portfolio of network traffic - video, voice, files, internet and radio.


TCP Acceleration Feature in OPUS Enhance

The purpose of the OPUS Enhance TCP Acceleration is to adapt the standard TCP/IP protocol for operation over satellite networks making the underlying TCP mechanisms and algorithms more effective in these environments.

Unlike PACE+ optimization and content compression techniques which aim to send less data to increase effective throughput, TCP Acceleration primarily (but not solely) sends the same amount of data as non-accelerated sessions, but sends this data in a more effective manner delivering increased throughput.

SCPS-TP Details

This feature is used to accelerate data transfers over TCP connections through use of the Space Communications Protocol Specification Transport Protocol (SCPS-TP) resulting in increased transfer speed. The OPUS SCPS-TP feature analyses traffic passing through an OPUS Node and identifies TCP traffic which can be accelerated, uses the SCPS-TP Connection Management capability to determine if this identified traffic is to path through a peer OPUS Node, and if this is the case, automatically establishes a SCPS ‘Full Reliability’ accelerated TCP connection which may use techniques such as:

  • Header Compression;
  • Selective Negative Acknowledgement (SNACK);
  • Window scaling;
  • Fast start;
  • Round Trip Time (RTT) measurement;
  • Retransmission Timeout (RTO) measurement.

The OPUS Enhance SCPS-TP feature is designed to the SCPS-TP standard and as such is interoperable with other SCPS-TP compliant devices. 

The OPUS Enhance SCPS-TP feature operates on TCP connections over IPv4 and IPv6 and as such both flows of a TCP connection must ALWAYS pass through the same pair of OPUS Nodes.

The OPUS Enhance SCPS-TP feature operates regardless of the location of the OPUS Node.


Vocality can provide consultancy and support in implementing SCPS and Vocality's own PACE+ technology into your network, your devices or service, in order to achieve dramatic satellite bandwidth reduction.

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