NS 2.35 柯志亨书实验4笔记随机数产生

上图是笔记。

测试了3条ftp流时，链路的吞吐量
通过采用不同的随机启动时间，得到不同的试验结果，可以平均一下

tcl代码：

# Kezhiheng, experiment 4, test RNG, 3 tcp flow

#Create a simulator object
set ns [new Simulator]

set tracefd [open out.tr w]
$ns trace-all $tracefd
set namtracefd [open out.nam w]
$ns namtrace-all $namtracefd

proc finish {} {
        global ns tracefd namtracefd
        $ns flush-trace
        close $tracefd
        close $namtracefd
    #    exec nam out.nam &
        exit 0
}

# 3 TCP flow
set nflow 3

# Set router nodes
set r1 [$ns node]
set r2 [$ns node]
$ns duplex-link $r1 $r2 1Mb 10ms DropTail
$ns queue-limit $r1 $r2 10

# Set TCP src, dest, link
for {set i 1} {$i<=$nflow} {incr i} {
    set s($i) [$ns node]
    set d($i) [$ns node]
    
    $ns duplex-link $s($i) $r1 10Mb 1ms DropTail
    $ns duplex-link $r2 $d($i) 10Mb 1ms DropTail
}

# Set TCP agent and FTP traffic
for {set i 1} {$i<=$nflow} {incr i} {
    set tcp($i)  [new Agent/TCP]
    set sink($i) [new Agent/TCPSink]
    $ns attach-agent $s($i) $tcp($i)
    $ns attach-agent $d($i) $sink($i)
    $ns connect $tcp($i) $sink($i)

    set ftp($i) [new Application/FTP]
    $ftp($i) attach-agent $tcp($i)
    $ftp($i) set type_ FTP
}

set rng [new RNG]
$rng seed 5

set rvStart [new RandomVariable/Uniform]
$rvStart use-rng $rng
$rvStart set min_ 0.0
$rvStart set max_ 1.0

for {set i 1} {$i<=$nflow} {incr i} {
    set startT($i) [expr [$rvStart value]]
#    puts "startT($i) $startT($i) sec"
    set endT($i) [expr ($startT($i)+5)]
#    puts "endT($i) $endT($i) sec"
    
    $ns at $startT($i) "$ftp($i) start"
    $ns at $endT($i)   "$ftp($i) stop"
}

$ns at 7.0 "finish"

$ns run

awk代码：

# Measure the throughput by the trace file

BEGIN{
    # program initialize
    init = 0;
    startT=0;
    endT=0;
}

{

action = $1;
time = $2;
from = $3;
to = $4;
type = $5;
pktsize = $6;
flow_id = $8;
src = $9;
dst = $10;
seq_no = $11;
packet_id = $12;

# Record pkttype=tcp, action=r, time 1s~5s
if(action=="r" && type=="tcp" && time>=1.0 && time<=5.0 && \
    ( (from==1 && to==3)||(from==1 && to==5)||(from==1 && to==5) ) )
{
    if(init==0)
    {
        startT = time;
        init = 1;
    }
    pkt_byte_sum += pktsize;
    endT=time;
}

}

END {
# When read over, start to calculate
printf("startT:%f,endT:%f\n",startT,endT);
printf("pkt_byte_sum:%d\n",pkt_byte_sum);
time = endT-startT;
throughput=pkt_byte_sum * 8 / time / 1000000;
printf("throughput:%.3f Mbps\n", throughput);
}

执行shell代码：

#!/bin/bash

ns rng_tcp.tcl

awk -f rng_tcp.awk out.tr

ftp flow为3条的测试结果：

-------------------------------
seed=1
startT:1.025972,endT:4.977268
pkt_byte_sum:266280
throughput:0.539 Mbps
-------------------------------
seed=2
startT:1.005634,endT:4.992002
pkt_byte_sum:353600
throughput:0.710 Mbps
-------------------------------
seed=3
startT:1.000912,endT:4.999952
pkt_byte_sum:320320
throughput:0.641 Mbps
-------------------------------
seed=4
startT:1.003102,endT:4.999262
pkt_byte_sum:246480
throughput:0.493 Mbps
-------------------------------
seed=5
startT:1.009901,endT:4.996269
pkt_byte_sum:271440
throughput:0.545 Mbps

可完善地方：
如果ns xxx.tcl
这句可以带参数，那么就可以在shell中，写循环测试不同数量ftp流的吞吐率了
外层循环使用ftp流的数量
内层循环使用随机数种子

后面将寻找实现方法，这样可以节省许多功夫，有谁知道的，要分享一下哦～