[ns] curious behaviour of the FTP application in ns2.1b6

[Michael Savoric <savoric@ftmail.ee.TU-Berlin.DE>]

Hi,
I have observed a curious behaviour of the FTP application in ns (Version
2.1b6) in conjunction with the (initial) congestion window size of a TCP agent.
With

$tcp set cwnd_ 1
$ftp produce $number_of_packets$

everything works as expected, i.e. the FTP application produces $number_of_packets
packets for the TCP agent. But, for example, with

$tcp set cwnd_ 5
$ftp produce $number_of_packets$

the FTP application produces more than $number_of_packets packets for the TCP
agent. This applies also for other cwnd_ values greater than 1. The same
behaviour of the FTP application can be observed with the functions produce and
send/sendmore. How can this be explained? Any ideas?

Best regards,
Michael Savoric
 
savoric@ee.tu-berlin.de