[ns] please help me

hi ,

i have a simple application which sends some data packet to a node and the node ,received packet, send ack data.The application uses a pointer to the agent in agent_.

i am able to send message to the node using agent_->sendmsg(.....).

and the dest node also able rx the packet.When i am trying to send the ack packet using(in the rx side) agent_->sendmsg(....) it crashes .it is not able to use agent_ with rx side.

can any one tell me what could be the problem.

I have defined a new agent from UDP which sends my data.

i have attached the part of the code .i am getting problem in the line colored Red.

In the receiver node i could not access the "object pointer " agent_.

Simply accessing the agent_ variable it self make segmentation fault.

please help me.

int simapp::command(int argc,const char*const* argv)
{
Tcl & tcl=Tcl::instance();
if(argc==2)
{
if(strcmp(argv[1],"start")==0)
{
  start();
}
}
if(argc==3)
{
if(strcmp(argv[1],"attach-app")==0)
{
static int i=0;
fprintf(stdout,"object count is %d",i);
agent_=(Agent*)TclObject::lookup(argv[2]);
fprintf(stdout,"agent address is %d \n",agent_);
if(agent_==0)
{
  tcl.resultf("no such a agent\n");
  return (TCL_ERROR);
}
if(agent_->supportMM())
  agent_->enableMM();

agent_->attachApp(this);
i++;
return (TCL_OK);
}
}
return(Application::command(argc,argv));
}

void simapp::init()
{
}

void simapp::start()
{
init();
sendpkt();
}

void simapp::stop()
{
}

void simapp::sendpkt()
{
hdr_simapp *sim;
agent_->sendmsg(6,"hello");
double next_time_=0.03;
snd_timer_.resched(next_time_);
}

void simapp::recv_msg(int bytes,const char *msg =0)
{
sendackpkt();
}

void simapp::sendackpkt()
{
agent_->sendmsg(4,"hai");
}

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persists in trying to adapt the world to himself. Therefore all progress
depends on the unreasonable man. -- George Bernard Shaw