[ns] RED does not drop packets

[Wen Shushan <wenss@uestc.edu.cn>]

Hi, ns-users,
When I use ns for a RED simulation. I found I can't control the gateway's
character through RED arguments. e.g.

Queue set limit_ 2	;#buffer size in pkts
#or I use Queue/RED to set buffer size directly
Queue/RED set limit_ 2
Queue/RED set maxthresh_ 1
Queue/RED set thresh_ 1
Queue/RED set setbit_  false	;#should drop pkts rather than mark them

The simulating result was different from what I had expected; the gateway
did not drop packets even when the TCP source transmits bursty 4 pkts to the
gateway.

If I did not use RED and I define the queue as DropTail, then the gateway will
drop packet just as expected.

Who can help me solve this problems?

Thanks!

Wen Shushan