Where can FAST TCP help?
TCP is useful whenever the availability of resources and the set of competing users vary over time unpredictably, yet efficient sharing is desired. In order to get high throughput end-to-end between applications, we must have a network infrastructure that can provide large raw capacity, and a protocol that can make efficient use of the high capacity infrastructure. The efficiency of the (congestion control algorithm in the) current TCP implementation drops steadily, and the protocol eventually becomes a performance bottleneck itself, as the network infrastructure scales up in capacity. FAST TCP aims to remove this bottleneck: it is scalable to networks with large bandwidth-delay product. FAST TCP does not solve the infrastructure problem: if the underlying hardware has low speed, no TCP implementation can increase the throughput beyond the limit imposed by the underlying hardware. It can at best be at the limit.
