TCP / IP factors over a satellite connection

A VSAT is often referred to as a long fat pipe network . This term refers to factors that affect TCP/ IP performance on any network that has relatively large bandwidth , but high latency . Most Internet connections in Africa and other parts of the developing world are via VSAT . Therefore , even if a university gets its connection via an ISP , this section might apply if the ISP's connection is via VSAT . The high latency in satellite networks is due to the long distance to the satellite and the constant speed of light .This distance adds about 520ms to a packet's round - trip time (RTT) , compared to a typicalRTT between Europe and the USA of about 140ms . 

tHE FACTORS that most significantly impact TCP  / Ip performance are long RTT , large bandwidth dela product , and transmission errors . 

Generally speaking , operating systems that supporty modern TCP/IP implementations should be used in a satellite network . These implementations support the RFC 1323 extensions : 

• The window scale option for supporting large TCP window sizes ( larger than 64kb) . 
• Selective acknowledgment (SACK) to enable faster recovery from transmission errors . 
• Timestamps for calculating approperiate RTT and retransmission timeout values for the link in use .