Hi,

I am simulating a TCP/FTP to TCP/FTP network and trying to monitor the packet loss.
I am able to monitor and graph data regarding the TCPSinks' bytes received, but I can't monitor packet loss.

Why is it that the TCPSink Agent has a variable for bytes (bytes_) but not one for monitoring packet loss?

Do I have to monitor the packet loss from the queue? If so, how do I write code for this?

Below is part of the code for monitoring bytes received from sinks if anyone was interested.


proc record {} {
global sink sink1 f0 f1 f2
#Get an instance of the simulator
set ns [Simulator instance]
#Set the time after which the procedure should be called again
set time 0.3
#How many bytes have been received by the traffic sinks?
set bw0 [$sink set bytes_]
set bw1 [$sink1 set bytes_]
#Get the current time
set now [$ns now]
#Calculate the bandwidth (in MBit/s) and write it to the files
puts $f0 "$now [expr $bw0/$time*8/1000000]"
puts $f1 "$now [expr $bw1/$time*8/1000000]"
#combination of f0 and f1
puts $f2 "$now [expr $bw0/$time*8/1000000+$bw1/$time*8/1000000]"
#Reset the bytes_ values on the traffic sinks
$sink set bytes_ 0
$sink1 set bytes_ 0
#Re-schedule the procedure
$ns at [expr $now+$time] "record"
}



Thank you for your help.
-Yida

May be try : Google .. Monitoring TCP Packet Loss in NS2 ..
http://www.google.com/webhp#hl=en&so...ca4f5b132e8dd5

Examples
http://nsnam.isi.edu/nsnam/index.php/Contributed_Code

http://www.eastman-watch.cn/ns-2-pra...ol-principles/
..

Sorry , browser hick up.



..

I did a fairly extensive google search before posting here.
I've visited the two links above and could not find code for what I needed.

Does anyone see a bug in this code:

First monittor the queue

set qfile [$ns monitor-queue $n2 $n3 [open queue.tr w] 0.05]
[$ns link $n2 $n3] queue-sample-timeout;


then write a prcodure to montior it

set prevDrops 0

proc record {} {
global ns qfile qsize qbw qlost n2 n3 prevDrops
set time 0.05
set now [$ns now]
$qfile instvar parrivals_ pdepartures_ bdrops_ bdepartures_ pdrops_
puts $qsize "$now [expr $parrivals_-$pdepartures_-$pdrops_]"
set bdepartures_ 0
set totalDrops [$qfile set pdrops_]
set currentDrops [expr $totalDrops - $prevDrops]
set prevDrops $totalDrops
puts $qlost "$now $currentDrops"
$ns at [expr $now+$time] "record"
}

May be ask @ emtarik05 :
http://www.linuxquestions.org/questi...arik05-516518/

Posts by @ emtarik05 are here
http://www.linuxquestions.org/questi...379/page5.html

http://www.linuxquestions.org/questi...379/page2.html
..