Re: cbr and udp packet size

[Haobo Yu <haoboy@isi.edu>]

> > Why the dimension of the packets transmitted  (in the trace-file) is 210 byte?
> > Beyond to the header (ip/udp) is there other?
> 
> use packet_size_ instead of packetSize_; 210 is just the dfault value (from 
> tcl/lib/ns-default.tcl)

210 is the default size, but packetSize_ should be used instead of
packet_size_. The latter is supported only for backward compability; see
tcl/lib/ns-source.tcl. 

BTW, I changed tcl/ex/simple.tcl to use my own CBR packet sizes and
rates, but I cannot repeat what you have observed. I've attached my script
for your comparison. 

- Haobo

set ns [new Simulator]

$ns color 0 blue
$ns color 1 red
$ns color 2 white

set n0 [$ns node]
set n1 [$ns node]
set n2 [$ns node]
set n3 [$ns node]

set f [open out.tr w]
$ns trace-all $f
set nf [open out.nam w]
$ns namtrace-all $nf

$ns duplex-link $n0 $n2 5Mb 2ms DropTail
$ns duplex-link $n1 $n2 5Mb 2ms DropTail
$ns duplex-link $n2 $n3 1.5Mb 10ms DropTail

$ns duplex-link-op $n0 $n2 orient right-up
$ns duplex-link-op $n1 $n2 orient right-down
$ns duplex-link-op $n2 $n3 orient right

$ns duplex-link-op $n2 $n3 queuePos 0.5

set udp0 [new Agent/UDP]
$ns attach-agent $n0 $udp0
set cbr0 [new Application/Traffic/CBR]
$cbr0 attach-agent $udp0
$cbr0 set packetSize_ 100
$cbr0 set rate_ 100Kb
#$cbr0 set interval_ 0.01

set udp1 [new Agent/UDP]
$ns attach-agent $n3 $udp1
$udp1 set class_ 1
set cbr1 [new Application/Traffic/CBR]
$cbr1 attach-agent $udp1
$cbr1 set packetSize_ 200
$cbr1 set rate_ 50Kb
#$cbr1 set interval_ 0.1

set null0 [new Agent/Null]
$ns attach-agent $n3 $null0

set null1 [new Agent/Null]
$ns attach-agent $n1 $null1

$ns connect $udp0 $null0
$ns connect $udp1 $null1

$ns at 1.0 "$cbr0 start"
$ns at 1.1 "$cbr1 start"

set tcp [new Agent/TCP]
$tcp set class_ 2
set sink [new Agent/TCPSink]
$ns attach-agent $n0 $tcp
$ns attach-agent $n3 $sink
$ns connect $tcp $sink
set ftp [new Application/FTP]
$ftp attach-agent $tcp
$ns at 1.2 "$ftp start"

$ns at 1.35 "$ns detach-agent $n0 $tcp ; $ns detach-agent $n3 $sink"

puts [$cbr0 set packetSize_]
puts [$cbr0 set interval_]

$ns at 3.0 "finish"

proc finish {} {
	global ns f nf
	$ns flush-trace
	close $f
	close $nf

	puts "running nam..."
	exec nam out.nam &
	exit 0
}

$ns run