Estimating Round Trip Times
Mean and standard deviation estimates made with exponential smoother:
- mean’ = (7/8)*mean + (1/8)*(rtt)
- sdev’ = (3/4)*sdev + (1/4)*abs(rtt-mean)
If rtt has low variance, then RTO will be only a little greater than the mean round trip time
If rtt has high variance, then RTO will be much greater than the mean round trip time
- combination of high loss and variable delay is bad for throughput