perf.eval: bandwidth estimation


caida (dovrolis) capacity estim. methodology  (2000)
effects of cross-traffic on measurement
packet pair technique by itself doesn't work if cross-traffic ignored
distribution of b/w measurements multi-modal
local modes often stronger than capacity mode
increasing train length helps
but estimates convert to under-estimate
implemented in pathrate  (caida)
accurate for capacities 10-40 Mbps at 1Mbps resolution
higher capacity paths require larger estimate resolution