Creating my own TCP

[Karim Benjelloun <kbenjell@caramail.com>]

Hello everybody,

I would like to personalize the current TcpAgent by
creating a subclass (say MyTcp) which  prints the seqno
everytime it receives a pkt. My idea was to create a
subclass extending TcpAgent, and redefine the virtual
procedure 'recv' to do the job.
Here is my listing :

----------------------------------------------------
set ns [new Simulator]
### Procedures
proc finish {} {
    global ns
    $ns flush-trace
    exit 0
}
Class MyTcp -superclass { Agent/TCP }
MyTcp instproc recv {pkt Handler} {
    eval $self next $pkt $Handler
    puts "pkt [$self seqno_]"
}
### Nodes
set n0 [$ns node]
set n1 [$ns node]
### Links
$ns duplex-link $n0 $n1 2MB 560ms DropTail
### TCPs
set src [new MyTcp]
   $ns attach-agent $n0 $src
set dst [new Agent/TCPSink]
   $ns attach-agent $n1 $dst
$ns connect $src $dst
### FTP
set ftp01 [new Application/FTP]
$ftp01 attach-agent $src
###Scheduler
$ns at 0.1 "$ftp start"
$ns at 60 "$ftp stop"
$ns at 60.1 "finish"
$ns run
----------------------------------------------------

The simulator runs fine, but no result appears on the
screen.

Thanks for help !

                Karim

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