What did they do?
They implemented an IP-layer coding mechanism on the layer-3 path that traversed the satellite link, effectively distributing every TCP packet across a number of transport packets (to minimize the effects of packet bursts on other TCP sessions) while also adding forward error correction to recover from reasonable packet loss rate without triggering TCP retransmissions.
Couldn’t they just use QoS?
Couldn’t they use intelligent shaping?
No idea. Teclo Networks is using intelligent per-session shaping to improve TCP goodput on mobile networks (more details in Software Gone Wild Episode 25), but I don’t know enough to judge whether their approach would work in environment with very large TCP RTT. Have to ask Juho…
Can’t we just fix TCP?
Maybe. While academics claim their machine-generated congestion control algorithms increased TCP throughput by almost a factor of 2, I’m not aware of any production experience, particularly in harsh environment (mobile or satellite)… and there might be a slight difference between theory and practice.
Obviously, if I’m missing something, please write a comment. Thank you!