Re: [ns] X-Mailer: Infom@il (correo con interfaz WEB)

[Debojyoti Dutta <ddutta@ISI.EDU>]

Try this 

$ns queue-limit $nagr $ndest 1 to set the limits. 

debo

On Fri, 25 May 2001, JORGE MANRIQUE MARGALEJO wrote:

> Hi all,
> 
> Sorry for bothering you again but I've found quite a weird problem when trying to simulate a simple 4-node scenario with two generator nodes, an aggregation node and a destination node. The traffic genrators I use are TCP and congestion is suffered on the aggregation node. I've set a queue "limit_" of 1 on que aggregation node and I expected to see packets being dropped with nam as soon as there were two elements on the queue, but the problem is I see the queue grow and grow and packets are not dropped until the queue is rally large (about 50 packest?). What's wrong with my code?:
> -
> -
> -
> #Create a simulator object
> set ns [new Simulator]
> 
> $ns color 1 Red
> $ns color 2 Blue
> 
> #Open the nam trace file
> set nf [open tcp1.nam w]
> $ns namtrace-all $nf
> 
> #Define a 'finish' procedure
> proc finish {} {
>         global ns nf
>         $ns flush-trace
> 	#Close the trace file
>         close $nf
> 	#Execute nam on the trace file
>         exec nam tcp1.nam &
>         exit 0
> }
> 
> #Create two nodes
> set n0 [$ns node]
> set n1 [$ns node]
> set nagr [$ns node]
> set nfin [$ns node]
> 
> 
> #Create a duplex link between the nodes
> $ns duplex-link $n0 $nagr 200kb 100ms DropTail
> $ns duplex-link $n1 $nagr 200kb 100ms DropTail
> $ns duplex-link $nagr $nfin 250kb 100ms DropTail limit_ 1
> $ns duplex-link-op $nagr $nfin queuePos 0.3
> 
> #Create a TCP agent and attach it to node n0
> set tcp0 [new Agent/TCP]
> $tcp0 set window_ 50
> $tcp0 set class_ 1
> $tcp0 set packetSize_ 500
> $ns attach-agent $n0 $tcp0
> set tcp1 [new Agent/TCP]
> $tcp1 set window_ 50
> $tcp1 set class_ 2
> $tcp1 set packetSize_ 500
> $ns attach-agent $n1 $tcp1
> 
> # Create a FTP traffic source and attach it to udp0
> set ftp0 [new Application/FTP]
> $ftp0 attach-agent $tcp0
> set ftp1 [new Application/FTP]
> $ftp1 attach-agent $tcp1
> 
> #Create a Null agent (a traffic sink) and attach it to node n1
> set sink0 [new Agent/TCPSink]
> $ns attach-agent $nfin $sink0
> set sink1 [new Agent/TCPSink]
> $ns attach-agent $nfin $sink1
> 
> 
> #Connect the traffic source with the traffic sink
> $ns connect $tcp0 $sink0  
> $ns connect $tcp1 $sink1  
> 
> #Schedule events for the CBR agent
> $ns at 0.5 "$ftp0 start"
> $ns at 0.6 "$ftp1 start"
> $ns at 4.5 "$ftp0 stop"
> $ns at 4.6 "$ftp1 stop"
> #Call the finish procedure after 5 seconds of simulation time
> $ns at 5.0 "finish"
> 
> #Run the simulation
> $ns run
> 
> Thanks a lot. Any help will be great, since I really can't figure out what the problem is.
> 
> Best regards,
> 
> Jorge Manrique
> 
>