Re: [ns] weird throughput result

[Kaleelazhicathu R R Kumar <kaleelaz@comp.nus.edu.sg>]

at the moment,you are actually counting the number of packets enqueued at
the node 1 and not the packets received at node 2 when u do a grep on
"+". Hence the rate u get now is the sending rate(15Mbps) and not the
throughput. Inorder to get the throuput , u may have to do a grep on
"r". you should get 10Mbps as the rest would be taildroped. to verify this
, u can count "d" packets. no. of "d" + "r" = "+".i think this would help.
 
Renjish.


If you love life, don't waste time, for time is what life is made up of.
-- Bruce Lee







On Tue, 23 Jan 2001, Devendra Goyal wrote:

> 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
> > >
> > >
> >
>