FAST TCP - Strengths and Weaknesses

Strengths and Weaknesses

Delay-based algorithms can, in principle, maintain a constant window size, avoiding the oscillations inherent in loss-based algorithms. However, they also detect congestion earlier than loss-based algorithms, since delay corresponds to partially filled buffers, while loss results from totally filled buffers. This can be either a strength or a weakness. If the only protocol used in a network is delay-based, then the inefficiency of loss can be avoided; however, if loss-based and delay-based protocols share the network, then delay-based algorithms tend to be less aggressive. This can be overcome by suitable choice of parameters, leading to complex interactions studied by Tang et al.

Delay measurements are also subject to jitter as a result of operating system scheduling, or bus contention.

Whether the strengths or weaknesses prevail is not clear, and depends in large part on the particular scenario.