Re: [ns] weird throughput result

[kunchanl <kunchanl@pollux.usc.edu>]

Can you explain how did you get those statistics in more details?

Kun-chan Lan

On Mon, 22 Jan 2001, Devendra Goyal wrote:

> I ran one experiment, created a link between two nodes with following
> specf.
> $ns duplex-link $n1 $n2 10Mb 1ms DropTail
> 
> and a cbr with following specf.
> $cbr0 set packetSize_ 1500
> $cbr0 set rate_ 15Mb
> 
> on running this, I get following output:
> For Packetsize= 1500 and Interval= 1.0 :
>         Application Load     	= 29.739659045857014 Mbs (enqueued packet)
>         Throughput              = 15.12356283864147 Mbs
>         Avg. Plus Delay         = 0.03948850052429101 sec
>         Avg. Minus Delay        = 0.001793289059769138 sec
>         Packet Drop Prob        = 0.4914681834340562
> 
> 
> The Throughput is more than the link bandwidth.
> I cannot explain this. Any idea...
> Thanks a lot
> DEV
> 
> The program is appended:
> 
> 
> #Create a simulator object
> set ns [new Simulator]
> 
> #Open the trace file
> set nf [open out.ex2 w]
> $ns trace-all $nf
> 
> #Define a 'finish' procedure
> proc finish {} {
>         global ns nf
>         $ns flush-trace
>         #Close the trace file
>         close $nf
>         exit 0
> }
> 
> #Create four nodes
> set n1 [$ns node]
> set n2 [$ns node]
> 
> #Create links between the nodes
> $ns duplex-link $n1 $n2 10Mb 1ms DropTail
> 
> #Create a UDP agent and attach it to node n0
> set udp0 [new Agent/UDP]
> $udp0 set class_ 1
> $ns attach-agent $n1 $udp0
> 
> # Create a CBR traffic source and attach it to udp0
> set cbr0 [new Application/Traffic/CBR]
> $cbr0 set packetSize_ 1500
> $cbr0 set rate_ 15Mb
> $cbr0 attach-agent $udp0
> 
> #Create a Null agent (a traffic sink) and attach it to node n3
> set null0 [new Agent/Null]
> $ns attach-agent $n2 $null0
> 
> #Connect the traffic sources with the traffic sink
> $ns connect $udp0 $null0
> 
> #Schedule events for the CBR agents
> $ns at 0 "$cbr0 start"
> $ns at 4.5 "$cbr0 stop"
> #Call the finish procedure after 5 seconds of simulation time
> $ns at 5.0 "finish"
> 
> #Run the simulation
> $ns run
> 
>