ns仿真之ftp和udp

set ns [new Simulator]
$ns color 1 Blue 
$ns color 2 Yellow
set nf [open out.nam w]
$ns namtrace-all $nf
#set nd [open out.tr w]
#$ns trace-all $nd
proc finish {} {
       global ns nf
       $ns flush-trace
       close $nf
       #close $nd
       exec nam out.nam &
        exit 0
}
set s1 [$ns node]
set s2 [$ns node]
set r [$ns node]
set d [$ns node]
$ns duplex-link $s1 $r 2Mb 10ms DropTail
$ns duplex-link $s2 $r 2Mb 10ms DropTail
$ns duplex-link $r $d 1.7Mb 20ms DropTail
$ns queue-limit $r $d 10
$ns duplex-link-op $s1 $r orient right-down
$ns duplex-link-op $s2 $r orient right-up
$ns duplex-link-op $r $d orient right
$ns duplex-link-op $r $d queuePos 0.5
#set tcp [new Agent/TCP]
#$ns attach-agent $s1 $tcp
#set sink [ new Agent/TCPSink]
#$ns attach-agent $d $sink
#$ns connect $tcp $sink
#$tcp set fid_ 1
#set ftp [new Application/FTP]
#$ftp attach-agent $tcp
#$ftp set type_ FTP
#$ns at 1.0 "$ftp start"
#$ns at 4.0 "$ftp stop"
set udp [new Agent/UDP]
$ns attach-agent $s2 $udp
set null [new Agent/Null]
$ns attach-agent $d $null
$ns connect $udp $null
$udp set fid_ 2
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
$ns at 0.1 "$cbr start"
$ns at 4.5 "$cbr stop"
$ns at 5.0 "finish"
$ns run

其中“#"号注释掉的部分是对ftp的仿真，直接运行后（只有udp）结果如下：