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[ns] Does Droptail have infinite queue?



Hi.

I found some strange things... in NS 2.1b6

Here is my network configuration

Sender-----link1-----router-----link2-----receiver

router use droptail both sides.
link1: 500Mbps 20msec RTT
link2 : 10Mbps 0.1msec RTT
Sender use TCP/Reno(all parameter default)
simulation time 100sec
throughput : about 3.9Mbps
link1's RTT 100msec(same bandwidth 500Mbps) throughput : 0.8Mbps
link1's RTT 20msec and bandwidth 500Mbps link2's RTT 0.1msec, 1Mbps :
throughput 1Mbps
and both simulation router doesn't discard any packet.
I think if router packet discarding occurs, low throughput is
reasonalble.
but no packet discard why tcp can't sends upto about 500Mbps?

I attach my tcl script..

Did I miss something?

Any information helpful.

Thx

1node.tcl