even ns2 version affects the pacing's results

After I changed from ns2.27 to ns2.28, the result of pacing changed, too.
Here are the new results (with 2.28) for competition of paced and non-paced tcp:
label with 1 is for pacing tcp and label with 2 is for non-paced tcp.

win is the aggregate congestion window
cut is the aggregate # of congestion reduction (# of loss event rate)
seq is the aggregate maxseq # (aggregate throughput)

Another strange thing to be make clear: the non-paced flows suffer significantly more cwnd cut than paced flows. but they still achieve higher throughput. Why?

Reno:


New Reno:


FACK:


In comparison, here is the corresponding results with ns2.27:
Reno:


NewReno:


FACK: