ns2 模拟器中没有显示输出

Question

#Create a simulator object
set ns [new Simulator]

#Define different colors for data flows (for NAM) 
$ns color 1 Blue
$ns color 2 Red

#Open the NAM trace file
set nf [open out.nam w]
$ns namtrace-all $nf

set nt [open test.tr w]
$ns trace-all $nt

#Define a 'finish' procedure
proc finish {} {
    global ns nf nt
    $ns flush-trace
    #Close the NAM trace file
    close $nf
    close $nt
    #Execute NAM on the trace file
    exec nam out.nam &
    exit 0
}

#Create four nodes
set n1 [$ns node]
set n2 [$ns node]
set n3 [$ns node]
set n4 [$ns node]
set n5 [$ns node]
set n6 [$ns node]

#Create links between the nodes
$ns duplex-link $n1 $n2 10Mb 10ms DropTail
$ns duplex-link $n2 $n3 10Mb 20ms DropTail
$ns duplex-link $n3 $n4 10Mb 10ms DropTail
$ns duplex-link $n5 $n2 10Mb 10ms DropTail
$ns duplex-link $n3 $n6 10Mb 10ms DropTail

#Set Queue Size of link (n2-n3) to 10
$ns queue-limit $n2 $n3 10

#Give node position (for NAM)
$ns duplex-link-op $n1 $n2 orient right-down
$ns duplex-link-op $n5 $n2 orient right-up
$ns duplex-link-op $n2 $n3 orient right
$ns duplex-link-op $n3 $n4 orient right-up
$ns duplex-link-op $n6 $n3 orient left-up

#Monitor the queue for link (n2-n3). (for NAM)
$ns duplex-link-op $n2 $n3 queuePos 0.5


#Setup a TCP connection
set tcp [new Agent/TCP]
$tcp set class_ 2
$ns attach-agent $n1 $tcp
set sink [new Agent/TCPSink]
$ns attach-agent $n4 $sink
$ns connect $tcp $sink
$tcp set fid_ 1

#Setup a FTP over TCP connection
set ftp [new Application/FTP]
$ftp attach-agent $tcp
$ftp set type_ FTP


#Setup a UDP connection
set udp [new Agent/UDP]
$ns attach-agent $n2 $udp
set null [new Agent/Null]
$ns attach-agent $n3 $sink
$ns connect $udp $sink
$udp set fid_ 2

#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"
$ns at 1.0 "$ftp start"
$ns at 4.0 "$ftp stop"
$ns at 4.5 "$cbr stop"

#Detach tcp and sink agents (not really necessary)
$ns at 4.5 "$ns detach-agent $n1 $tcp ; $ns detach-agent $n4 $sink"

我正在尝试通过此链接 http://www.ccs.neu.edu/home/cbw/4700/project3.html 执行示例 1。但由于某种原因，在终端中输入 ns sample.tcl 后，只显示“puts”部分，没有 nam 输出。

#Call the finish procedure after 5 seconds of simulation time
$ns at 5.0 "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

Answer 1

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请从这里开始了解基础知识 (Marc Greiss) http://www.isi.edu/nsnam/ns/tutorial/nsscript1.html

示例：“examples_1-2-3-4.tar.gz”https://drive.google.com/file/d/0B7S255p3kFXNakF3X0FHby1aYlU/view?usp=sharing

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