A fair amount of press has focused on TCP/IP, the networking protocol that the Internet and the World Wide Web (WWW) rely on, for not working properly over satellite transmissions. Satellite can support very high-speed communications such as multimegabit speeds. The claims are that the TCP/IP reference implementation s 4K buffer size limits channel capacity and data throughput to only 64 Kbps. The argument is then used that the maximum buffer of 64K limits maximum throughput to 1 Gbps. Therefore, the argument continues that GEO Ka-band satellite services are unsuitable for high-bandwidth applications as the increased latency of a GEO connection decreases the available bandwidth.

TCP buffers are sized as

With a limited buffer size, a longer end-to-end delay decreases the space available to hold spare copies of unacknowledged data for retransmission. This limits the throughput on a lossless TCP connection.

However, this argument ignores the work done on larger buffer sizes for TCP in RFC 1323, the large windows effort. Work to expand TCP beyond its original 16-bit buffer space has been going on for several years. Moreover, the effort and result of large windows is supported by several versions of UNIX. The TCP buffer limit isn t as bad as it s made out to be. TCP copes with GEO delays quite nicely today. Individual high-bandwidth GEO TCP links are possible with the right equipment and software. Military applications have been using TCP/IP in many GEO-based networks for years.

GEO links are suitable for seamless...