[ns] Newbie application questions

[Sahil Sunil Rihan <srihan@stanford.edu>]

Hi all!

I've just gotten started using ns and need to model how a particular
application affects network congestion.

The application in question will be run by user's on their terminals. It
is assumed that the user's will be connected to the internet via a modem.

When a particular user node receives a packet from another user node, it
needs to selectively send it to a varying group of other  user node's that
it is aware about. 

I've been trying to use the UDP recv method to receive event
notification and use a separate connection to send out the response
messages. But this doesnt seem to be working. I've also tried using
something like $ns at now + 0.2 "$conn3 send 200", in case this was due 
to synchro. problems, but without any luck.

Any help will be greatly appreciated.

Thanks in advance,
Sahil Rihan