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_ = [$cbr set packet_size_]" puts "CBR interval = [$cbr set interval_]"