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Komunikasi Digital (TEP 651)
NS-2 Simulation
Dr. I Wayan Mustika, ST., M.Eng.
Jurusan Teknik Elektro dan Teknologi Informasi FT UGM
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Outline
ns2- Network Simulator Wired Network Wireless Network
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ns2- Network Simulator
One of the most popular simulator among networking
researchers.
Discrete event, Packet level simulator Events like received an
ack packet, enqueued a
data packet Network protocol stack written in C++ Tcl (Tool
Command Language) used for
specifying scenarios and events. Unix Based. Runs also in
windows using cygwin Simulates both wired and wireless
networks.
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Wired Creating a simple two node network topology Adding traffic
to the link UDP traffic TCP traffic Fault injection
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Simple two node wired network
n0 n1
#Create a simulator object set ns [new Simulator] Step 1:
Step 2: #Open trace files set f [open out.tr w] $ns trace-all
$f
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n0 n1
#Create two nodes set n0 [$ns node] set n1 [$ns node]
Step 3:
Step 4: #Create a duplex link between the nodes $ns duplex-link
$n0 $n1 1Mb 10ms DropTail
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#Create a simulator object set ns [new Simulator] #Open trace
files set f [open out.tr w] $ns trace-all $f #Define a 'finish'
procedure proc finish {} { global ns $ns flush-trace exit 0 }
#Create two nodes set n0 [$ns node] set n1 [$ns node] #Create a
duplex link between the nodes $ns duplex-link $n0 $n1 1Mb 10ms
DropTail #Call the finish procedure after 5 seconds of simulation
time $ns at 5.0 "finish" #Run the simulation $ns run
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Adding traffic to the link
n0 n1
udp
#Create a UDP agent and attach it to node n0 set udp0 [new
Agent/UDP] $ns attach-agent $n0 $udp0
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n0 n1
udp
# Create a CBR traffic source and attach it to udp0 set cbr0
[new Application/Traffic/CBR] $cbr0 set packetSize_ 500 $cbr0 set
interval_ 0.005 $cbr0 attach-agent $udp0
cbr
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n0 n1
udp
cbr
#Create a Null agent (a traffic sink) and attach it to node n1
set null0 [new Agent/Null] $ns attach-agent $n1 $null0
null
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n0 n1
udp
cbr
#Connect the traffic source with the traffic sink $ns connect
$udp0 $null0 #Schedule events for the CBR agent $ns at 0.5 "$cbr0
start" $ns at 4.5 "$cbr0 stop
null
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Trace Analysis
http://nsnam.isi.edu/nsnam/index.php/NS-2_Trace_Formats
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Wireless Simulation
Defining wireless options Create & define topology Create
God General Operations Descriptor Configure node Create nodes
Provide start positions Create movement Set connections Schedule
traffic events Define initial position in NAM Tell nodes when the
simulation ends Ending NAM and the simulation
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Performance Metrics
We will try to evaluate the routing protocols in terms of two
metrics
1. Packet delivery fraction : It is the ratio of packets
delivered to that generated by the traffic generator.
2. Routing load : It is the number of routing packets required
to be sent per data packet delivered.
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Trace file name: simple-dsdv.tr. Use following command to get
the number of packets sent
by the traffic source. grep "^s.*\-Nl AGT.*\-It cbr.*"
simple-dsdv.tr | wc l
Now, use following command to get the actual number of packets
received at the destination. grep "^r.*\-Nl AGT.*\-It cbr.*"
simple-dsdv.tr | wc l
Calculate Packet Delivery Fraction using (received packets/sent
packets)
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Use following command to get the total number of routing packets
sent. grep "^\(s\|f\).*\-Nl RTR.*\-It message.*" simple-dsdv.tr |
wc l Calculate Routing Load using (routing packets/received
packets)
