NS网络模拟和协议仿真源代码.doc

第4章
例1
#建立一个模拟
set ns [new Simulator]
#定义不同数据流的颜色(NAM显示时用到)
$ns color 1 Blue
$ns color 2 Red
#开启Trace跟踪和NAM跟踪
set tracefd [open w]
$ns trace-all $tracefd
set nf [open w]
$ns namtrace-all $nf
#定义结束进程
proc finish {} {
global ns tracefd nf
$ns flush-trace
close $tracefd
close $nf
exit 0
}
#定义节点
set n0 [$ns node]
set n1 [$ns node]
set n2 [$ns node]
set n3 [$ns node]
set n4 [$ns node]
set n5 [$ns node]
#$n5 color black
$n5 color red
#定义节点间的链路
$ns duplex-link $n0 $n1 2Mb 10ms DropTail
$ns duplex-link $n1 $n2 2Mb 10ms DropTail
$ns duplex-link $n1 $n4 2Mb 20ms DropTail
$ns duplex-link $n3 $n4 2Mb 10ms DropTail
$ns duplex-link $n4 $n5 2Mb 10ms DropTail
#定义链路的队列长度
$ns queue-limit $n1 $n4 10
#指定节点间的相互位置(NAM显示用到)
$ns duplex-link-op $n0 $n1 orient right-down
$ns duplex-link-op $n2 $n1 orient right-up
$ns duplex-link-op $n1 $n4 orient right
$ns duplex-link-op $n3 $n4 orient left-down
$ns duplex-link-op $n5 $n4 orient left-up
#监视链路的队列
$ns duplex-link-op $n1 $n4 queuePos
#建立一个TCP连接
set tcp [new Agent/TCP]
$tcp set class_ 2
$ns attach-agent $n0 $tcp
set sink [new Agent/TCPSink]
$ns attach-agent $n5 $sink
$ns connect $tcp $sink
$tcp set fid_ 1
#在TCP连接上建立FTP流
set ftp [new Application/FTP]
$ftp attach-agent $tcp
$ftp set type_ FTP
#建立一个UDP代理
set udp [new Agent/UDP] ;#建立一个数据发送代理
$ns attach-agent $n2 $udp ;#将数据发送代理绑定到发送节点
set null [new Agent/Null] ;#建立一个数据接收代理
$ns attach-agent $n3 $null ;#将数据接收代理绑定到接收节点
$ns connect $udp $null ;#连接两个代理(也就决定了数据包的发送和接收节点)
$udp set fid_ 2
#在UDP代理上建立CBR流
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
#启动和结束流代理
$ns at "$cbr start"
$ns at "$ftp start"
$ns at "$ftp stop"
$ns at "$cbr stop"
$ns at "$ns detach-agent $n0 $tcp; $ns detach-agent $n5 $sink"
#仿真结束时调用结束进程
$ns at "finish"
#打印CBR数据包的大小和间隔
puts "CBR packet_size_ = [$cbr set