Re: [ns] weird throughput result

[Devendra Goyal <goyald@email.uc.edu>]

I run the program. Process the trace file.
get total_send_packet_count using 'grep -cw "+" tracefile'.
and the same way total_received_packet_count.
Then
Application Load=total_send_packet_count*packet_size*8(bits per
byte) / total_time.
Throughput=total_received_packet_count*packet_size*8(bits per
byte) / total_time.

I get the total time from my simulation time or last packet time stamp
from trace file.

It just clisks me. My results are almost double of expected results.
Does it have something to do with the duplex link?
Thanks a lot.
DEV

On Mon, 22 Jan 2001, kunchanl wrote:

> 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
> >
> >
>