Re: Callback function instead of trace-file?

["Christoph Haenle" <christoph@starburstcom.com>]

Hi again,

> > I'm using ns-2b18 and need a possibility to see what happens to certain
> > packets inside the network. I thus need to monitor the links. However,
my
> > simulation has a large number of links and my logfiles become soon very
> > large (ca 10MB/min) if I log everything. In order to run simulations
> > overnight, I don't want all traces to be written to disk. Rather, I'm
> > looking for some possibility to register a callback-function that is
called
> > whenever a packet is enqueued, dequeued or lost on a link. If I
remember
> > right, this functionality was implemented in ns-1.4, but I can't find
it in
> > ns-2.
> > If nothing else helps, I could open a named pipe with Tcl, have ns
write
> > everything to the pipe and read & parse everything that arrives on the
> > other end. But that would pretty much be a hack. Moreover, I would need
> > multithreading support (for running ns and the evaluation of the traces
> > simultaneously).
> > 
> >      Any suggestions?
> > 
> >        TX,
> > 
> >          -Chris.
> 
> Can you describe a bit more of your application?  Do you need to
> take some action other than statistic gathering when packets
> {arrive/depart/are dropped}?
> 
> - K

I'm simulating the behaviour (error recovery, congestion control) of
different multicast protocols (at least SRM and MFTP) in a fictive
large-scale network in which lots of fictive TCP-connections run. To see
for example how much the TCP-connections suffer from MFTP, I must observe
the packet loss on the various links and seperate it into TCP-connections
and MFTP (e.g. with the help of different flow_id's). Or I want to observe
potential NAK-implosions with MFTP, i.e. look at every dropped packet from
where it has came.
Further, I want to trace a repair-packet and see over which links it
travels in order to determine the network utilization by this particular
packet.

I'd need a custom-callback-event-handler to further evaluate a packet loss
or to trace a packet on it's way through the net.

    -Chris.