TCP flow control has two modes: softboost and hardboost.
Softboost uses a rate-based sender that sends accelerated traffic at speeds up to the link's bandwidth limit. If the bandwidth limit is set slightly lower than the link speed, packet loss and latency are minimized, while link utilization is maximized. Interactive applications see fast response times while bulk-transfer applications see high bandwidth. Softboost shares the network with other applications in any topology, and it interoperates with third-party QoS systems.
Hardboost is more aggressive than softboost. By ignoring packet losses and other so-called "congestion signals," it performs very well on links plagued with heavy, non-congestion-related losses, such as satellite links. It is also excellent on low-quality, long-haul links with a high background packet loss, such as many overseas links. Hardboost is recommended only for point-to-point links that do not achieve adequate performance with softboost.
Softboost is the default mode and is recommended in most cases.
To select hardboost mode