Analysis of the process of configuring a simple network environment based on Tcl language

#Set some properties needed for simulation set val(chan) Channel/WirelessChannel
set val(prop) Propagation/TwoRayGround
set val(netif) Phy/WirelessPhy
set val(mac) Mac/802_11
#After setting the protocol to DSR, set the queue to CMUPriQueue
set val(ifq) CMUPriQueue
set val(ll) LL
set val(ant) Antenna/OmniAntenna
set val(ifqlen) 50
#Preset the number of nodes to 0 and wait for user input. This item requires user input, otherwise the simulation will not be performed.
set val(nn) 0
set val(rp) DSR
#The default value of the scene size is 1000*1000
set val(x) 1000
set val(y) 1000
#The default radius of the circle is 400
set val(r) 400
#This procedure is used to print on the screen. Type ns circle.tcl in the terminal and then add the parameter format proc usage {} {
  global argv0
  puts "\nusage: $argv0 \[-nn nodes\] \[-rr\] \[-xx\] \[-yy\]\n"
  puts "note: \[-nn nodes\] is essential, and the others are optional.\n"
}
#This procedure is used to change the values ​​of some preset parameters according to user input. proc getval {argc argv} {
  global val
  lappend vallist nn rxyz
  #argc is the number of parameters, argv is the string consisting of the entire parameter for {set i 0} {$i < $argc} {incr i} {
    #The variable arg is the i-th part of argv, separated by spaces. set arg [lindex $argv $i]
    #Skip the string without the character "-", which is usually a number typed by the user. #string range $arg mn means taking the mth character to the nth character of the string $arg if {[string range $arg 0 0] != "-"} continue
    set name [string range $arg 1 end]
    #Change preset variables (number of nodes, radius, scene size)
    set val($name) [lindex $argv [expr $i+1]]
  }
}
#Call getval procedure getval $argc $argv
#The user did not enter any parameters, but only typed ns circle.Tcl, so the number of nodes is assumed to be 0
if { $val(nn) == 0 } {
  #Print usage
  exit
}

#Create a simulation instance set ns [new Simulator]

#Set the record file set tracefd [open circle.tr w]
$ns trace-all $tracefd
set namtracefd [open circle.nam w]
$ns namtrace-all-wireless $namtracefd $val(x) $val(y)

#Close the trace file and call the nam program to demonstrate the animation proc finish { } {
	global ns tracefd namtracefd
	$ ns flush-trace
	close $tracefd
	close $namtracefd
	exec nam circle.nam &
	exit 0
}

set topo [new Topography]
$topo load_flatgrid $val(x) $val(y)

create-god $val(nn)
#Node configuration. Due to version reasons, addressType is set to def
$ns node-config -addressType def\
-adhocRouting $val(rp) \
    -llType $val(ll) \
    -macType $val(mac)\
    -ifqType $val(ifq) \
    -ifqLen $val(ifqlen) \
    -antType $val(ant) \
    -propType $val(prop) \
    -phyType $val(netif) \
    -channelType $val(chan) \
    -topoInstance $topo \
    -agenttrace ON \
    -routertrace ON \
    -mactrace OFF \
    -movementtrace OFF

# Initialize the node for {set i 0} {$i < $val(nn)} {incr i} {
#Create a node set node_($i) [$ns node]
$node_($i) random-motion 0
#Calculate the node position and set it, using trigonometric functions $node_($i) set X_ [expr $val(r) * cos($i * 2 * 3.14159 / $val(nn))]
  $node_($i) set Y_ [expr $val(r) * sin($i * 2 * 3.14159 / $val(nn))]
$node_($i) set Z_ 0
#Set the display size of the mobile node in nam, otherwise, the node cannot be displayed in nam $ns initial_node_pos $node_($i) [expr $val(x) / 10]
}

#Create a UDP agent on node_(0) set tcp [new Agent/UDP]
$ns attach-agent $node_(0) $tcp
#Create a data receiver on the node opposite to node(0) along the diameter set null [new Agent/Null]
$ns attach-agent $node_([expr $val(nn)/2]) $null
#Create a new CBR traffic generator, with a packet size of 500B and an interval of 0.05s
set cbr [new Application/Traffic/CBR]
$cbr set packetSize_ 5000
$cbr set interval_ 0.05
#Connect UDP and Null
$cbr attach-agent $tcp
$ns connect $tcp $null
#Send data at 0.1s, stop sending data at 3.0s, and call the finish process at 5.0s $ns at 0.1 "$cbr start"
$ns at 3.0 "$cbr stop"
$ns at 5.0 "finish"
$ns run

BEGIN {
#Set initial variables num_D = 0; #Number of lost packets num_s = 0; #Number of sent packets num_r = 0; #Number of received packets rate_drop = 0; #Packet loss rate sum_delay = 0; #Total delay time average_delay = 0; #Average delay time}
{
	#Read the trace file record event = $1; #The first column is the packet operation (s is the sending packet, r is the receiving packet)
	time = $2; #The second column is the operation time node = $3; #The third column is the node number trace_type = $4; #The fourth column is the operation layer flag = $5; #The fifth column is the flag uid = $6; #The sixth column is the node identifier pkt_type = $7; #The seventh column is the packet type pkt_size = $8; #The eighth column is the packet size #Operation if (event == "s" && trace_type == "AGT" && pkt_type == "cbr")
	{ send_time[uid] = time; #Create an array to record the time of sending packets num_s++; #Record the total number of packets sent }
	if (event == "r" && trace_type == "AGT" && pkt_type == "cbr")
	{ delay[uid] = time - send_time[uid]; #Create an array to record the delay time num_r++; #Record the total number of packets received }
	if (event == "D" && pkt_type == "cbr")
		delay[uid] = -1; #-1 means the packet is lost and the packet will not be recorded in the delay time}

END {
	#Calculate the number of packet losses and packet loss rate num_D = num_s-num_r; #Total number of packet losses rate_drop = num_D / num_s * 100.0; #Calculate the packet loss rate	
	#Calculate delay for ( i = 0; i < num_s; i++)
		{if (delay[i] >= 0)
			sum_delay += delay[i];
		}#Total delay time average_delay = sum_delay / num_r; #Average delay time #Print results printf("number of packets dropped: %d \n",num_D);
	printf("number of packets sent: %d \n",num_s);
	printf("drop rate: %.3f%% \n",rate_drop);
	printf("average delay time: %.9f \n",average_delay);
}