Komunikasi Digital (TEP 651)

NS-2 Simulation

Dr. I Wayan Mustika, ST., M.Eng.

Jurusan Teknik Elektro dan Teknologi Informasi FT UGM

Outline

ns2- Network Simulator Wired Network Wireless Network

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.

Wired Creating a simple two node network topology Adding traffic to the link UDP traffic TCP traffic Fault injection

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

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

#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

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

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

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

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

Trace Analysis

http://nsnam.isi.edu/nsnam/index.php/NS-2_Trace_Formats

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

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.

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)

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)