# Creates a simulator object
set ns [new Simulator]
#trace file name meshout.tr will keep record of network data flow
set nf [open meshout.tr w]
$ns trace-all $nf
# trace file named meshout.nam will keep record of data flow
set fr [open meshout.nam w]
$ns namtrace-all $fr
#colors for data flow in NAM
$ns color 1 Blue
$ns color 2 Orange
$ns color 3 Red
# defining all 6 workstation nodes
for {set i 0} {$i<5} {incr i} {
set n($i) [$ns node]
}
# finish procedure
proc finish {} {
global ns nf fr
$ns flush-trace
# Close NAM and TR trace files
close $fr
close $nf
# Execute NAM on trace file
exec nam meshout.nam &
exit 0
}
# Establish links between nodes
$ns duplex-link $n(0) $n(1) 5Mb 2ms DropTail
$ns duplex-link $n(0) $n(2) 5Mb 2ms DropTail
$ns duplex-link $n(0) $n(3) 5Mb 2ms DropTail
$ns duplex-link $n(0) $n(4) 5Mb 2ms DropTail
$ns duplex-link $n(1) $n(2) 5Mb 2ms DropTail
$ns duplex-link $n(1) $n(3) 5Mb 2ms DropTail
$ns duplex-link $n(1) $n(4) 5Mb 2ms DropTail
$ns duplex-link $n(2) $n(3) 5Mb 2ms DropTail
$ns duplex-link $n(2) $n(4) 5Mb 2ms DropTail
$ns duplex-link $n(3) $n(4) 5Mb 2ms DropTail
# Queue Size for links set to 5
$ns queue-limit $n(1) $n(2) 5
$ns queue-limit $n(3) $n(4) 5
$ns queue-limit $n(4) $n(0) 5
#n1 to n3
# Setup a TCP connection
set tcp1 [new Agent/TCP]
$tcp1 set class_ 2
$ns attach-agent $n(1) $tcp1
set sink1 [new Agent/TCPSink]
$ns attach-agent $n(3) $sink1
$ns connect $tcp1 $sink1
$tcp1 set fid_ 1
# Setup a FTP over TCP connection
set ftp1 [new Application/FTP]
$ftp1 attach-agent $tcp1
$ftp1 set type_ FTP
#n2 to n1
# Setup a TCP connection
set tcp2 [new Agent/TCP]
$tcp2 set class_ 2
$ns attach-agent $n(2) $tcp2
set sink2 [new Agent/TCPSink]
$ns attach-agent $n(1) $sink2
$ns connect $tcp2 $sink2
$tcp2 set fid_ 2
# Setup a FTP over TCP connection
set ftp2 [new Application/FTP]
$ftp2 attach-agent $tcp2
$ftp2 set type_ FTP
#between n0 and n3
# Setup a UDP connection
set udp [new Agent/UDP]
$ns attach-agent $n(0) $udp
set null [new Agent/Null]
$ns attach-agent $n(3) $null
$ns connect $udp $null
$udp set fid_ 3
# Setup a CBR over UDP connection
set cbr [new Application/Traffic/CBR]
$cbr attach-agent $udp
$cbr set type_ CBR
$cbr set packet_size_ 1000
$cbr set rate_ 1mb
$cbr set random_ false
# Schedule events for the CBR and FTP agents
$ns at 0.1 "$cbr start"
$ns at 2.7 "$cbr stop"
$ns at 0.3 "$ftp1 start"
$ns at 2.3 "$ftp1 stop"
$ns at 0.5 "$ftp2 start"
$ns at 2.5 "$ftp2 stop"
# Detach tcp and sink agents
# (not really necessary)
$ns at 3.0 "$ns detach-agent $n(1) $tcp1 ; $ns detach-agent $n(3) $sink1"
$ns at 3.0 "$ns detach-agent $n(2) $tcp2 ; $ns detach-agent $n(1) $sink2"
# Call the finish procedure after 3 seconds simulation
$ns at 3.0 "finish"
# Print CBR packet size and interval
puts "CBR packet size = [$cbr set packet_size_]"
puts "CBR interval = [$cbr set interval_]"
# Run the simulation
$ns run
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Public Module Program
Public Sub Main(args() As string)
Dim name as String = Console.ReadLine() ' Reading input from STDIN
Console.WriteLine("Hello " & name) ' Writing output to STDOUT
End Sub
End Module
Visual Basic is a event driven programming language by Microsoft, first released in the year 1991.
Variable is a name given to the storage area in order to identify them in our programs.
Simple syntax of Variable declaration is as follows
Dim variableName [ As [ New ] dataType ] [ = initializer ]
variableName = value
If condition-expression Then
'code
End If
If(conditional-expression)Then
'code if the conditional-expression is true
Else
'code if the conditional-expression is false
End If
If(conditional-expression)Then
'code if the above conditional-expression is true
Else If(conditional-expression) Then
'code if the above conditional-expression is true
Else
'code if the above conditional-expression is false
End If
If(conditional-expression)Then
'code if the above conditional-expression is true
If(conditional-expression)Then
'code if the above conditional-expression is true
End If
End If
Select [ Case ] expression
[ Case expressionlist
'code ]
[ Case Else
'code ]
End Select
For counter [ As datatype ] = begin To end [ Step step ]
'code
[ Continue For ]
'code
[ Exit For ]
'code
Next [ counter ]
For Each element [ As datatype ] In group
'code
[ Continue For ]
'code
[ Exit For ]
'code
Next [ element ]
While conditional-expression
'Code
[ Continue While ]
'Code
[ Exit While ]
'Code
End While
Do { While | Until } conditional-expression
'Code
[ Continue Do ]
'Code
[ Exit Do ]
'Code
Loop
Do
'Code
[ Continue Do ]
'Code
[ Exit Do ]
'Code
Loop { While | Until } conditional-expression
Procedure is a sub-routine which contains set of statements. Usually Procedures are written when multiple calls are required to same set of statements which increases re-usuability and modularity.
Procedures are of two types.
Functions return a value when they are called.
[accessModifiers] Function functionName [(parameterList)] As returnType
'code
End Function
Sub-procedures are similar to functions but they don't return any value.
Sub ProcedureName (parameterList)
'Code
End Sub