Tcptrace Throughput Graph

Yellow Dots

The yellow dots are the "instantaneous throughput", which is defined as the size of the segment that caused it divided by the time elapsed since the previous segment arrived. Due to clock granularity, there tends to be a lot of banding in these points

Blue Line

The blue line is the average throughput over the life of the connection to that point (total bytes / total seconds).

Red Line

The red line is easiest to describe as an average of the previous N yellow dots. It's the throughput of the last few samples. By default, N is 10, but you can change that with the "-AN" argument.