NS2模拟教程-优快云博客

链接：http://blog.chinaunix.net/u3/105477/showart_2088091.html

关注点：

采样过程的编写！

Xgraph、Nam在Finish proc中调用的简单命令！

#============================================
# 对NS2入门实例3的深入研究
# 通过采样测量应用CBR和FTP的吞吐量、丢包率、时延
#============================================
# 代码注释请参考NS2入门实例3
set ns [new Simulator]
$ns color 1 Blue
$ns color 2 Red
set nf [open out.nam w]
$ns namtrace-all $nf
set nd [open out.tr w]
$ns trace-all $nd
#用于记录采样结果的文件
set f0 [open cbr-throughput.tr w]
set f1 [open cbr-loss.tr w]
set f2 [open ftp-throughput.tr w]

set last_ack 0
#采样过程的代码编写
proc record {} {
global ns null tcp f0 f1 f2 last_ack
set time 0.5     ;#Set Sampling Time to 0.5 Sec
set a [$null set bytes_] ;# CBR/UDP--Through
set b [$null set nlost_] ;# CBR/UDP--Loss
set c [$tcp set ack_]     ;# FTP/TCP--Through
set d [$tcp set packetSize_]
set now [$ns now]

# Record Bit Rate in Trace Files， CBR--Throughput
    puts $f0 "$now [expr $a*8/$time]"

    # Record Packet Loss Rate in File，CBR--loss
    puts $f1 "$now [expr $b/$time]"

    if { $c >0} {
       set e [expr $c - $last_ack]
       puts $f2 "$now [expr $e*$d*8/$time]"
       set last_ack $c ;#注意哦：更新last_ack, 以便用于进行下一时刻的采样计算
    } else {
       puts $f2 "$now 0"
    }
    # Reset Variables
    $null set bytes_ 0
    $null set nlost_ 0

    $ns at [expr $now+$time] "record" ;# Schedule Record after $time interval sec
}

proc finish {} {
        global ns nf nd f0 f1 f2
        $ns flush-trace
        close $nf
        close $nd
        close $f0
        close $f1
        close $f2
        # Plot Recorded Statistics
     exec xgraph cbr-throughput.tr ftp-throughput.tr -geometry 800x400 &
     exec xgraph cbr-loss.tr -geometry 800x400 &
        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

#设置FTP/TCP的部分
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

#设置CBR/UDP的部分
set udp [new Agent/UDP]
$ns attach-agent $s2 $udp
set null [new Agent/LossMonitor]
$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

#模拟时间的设定
$ns at 0.0 "record"
$ns at 0.1 "$cbr start"
$ns at 1.0 "$ftp start"
$ns at 4.0 "$ftp stop"
$ns at 4.5 "$cbr stop"
#此行代码可有可无，暂时不管啊！
$ns at 4.5 "$ns detach-agent $s1 $tcp ; $ns detach-agent $d $sink"

$ns at 5.0 "finish"
$ns run