Epilog|NETWORK SIMULATIONS: NS-2
Simulations using ns (either ns-2 or ns-3) are a central part of networks research. Most scientific papers addressing comparisons between TCP flavors refer to ns simulations to at least some degree; ns is also widely used for non-TCP research (especially wireless).
But simulations are seldom a matter of a small number of runs. New protocols must be tested in a wide range of conditions, with varying bandwidths, delays and levels of background traffic. Head-to-head comparisons in isolation, such as our first runs in 31.3.3 Unequal Delays, can be very misleading. Good simulation design, in other words, is not easy.
Our simulations here involved extremely simple networks. A great deal of effort has been expended by the ns community in the past decade to create simulations involving much larger sets of nodes; the ultimate goal is to create realistic simulations of the Internet itself. We refer the interested reader to [FP01]