Queuing Models in NS2

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M/M/1 is a system with poisson arrival time, servicing exponentially and a queue of unlimited capacity and type of FIFO Queue. This is the simplest queuing system.  NS2 supports various distributions like pareto, exponential, constant, unifrom, etc to handle the network dynamics and metrics. So it is very easy to test the given network link to monitor a given queue using any of these queuing models. The listing 3 and 4 are monitoring the link when DropTail queue is used with a capacity of finite and infinite. Listing 13.3 uses infinite capacity and Listing 13.4 uses Finite capacity The output screen shot is shown below the scripts for further understanding
Listing 3 – M/M/1 Queuing Model #new Simulator creation set ns [new Simulator] #trace file creation for capturing the UDP data set tf [open out.tr w] $ns trace-all $tf
#setting the exponential distribution param set lambda 30.0 set mu     33.0
#creation of nodes set n1 [$ns node] set n2 [$ns node] #The queue limit is 1Lakh as the capacity is infin…

Creating a New Agent in Network Simulator 2

How to create a new agent in NS2. You can use any version of the Simulator. The following codes will make you to understand the writing of a sample agent.

Requirements:

  • NS2 Simulator
  • A tcl file to test the compiled agent

If any two values are supplied from the TCL file, the agent computes the Surface area of the Cylinder which is nothing but (2* PI * r * h).  The supplied values from TCL file are r and h.

How to do that.

1. Copy the newagent.cc (given below ) file in ~ns-allinone-2.34/ns-2.34/newfolder
2. Make an entry in the ~ns-2.34/Makefile.in
    Make an entry in the OBJ_CC =
            newfolder/newagent.o \
3. in the shell prompt, go to ~ns-2.34 and give the command
./configure
make
4. run the file agent_new.tcl (given below)
you can see the output

Here is the C++ code to be written and compiled

//Name of the file is newagent.cc and put it in a folder inside ~ns-2.34/newfolder/
#include <stdio.h>
#include <string.h>
#include "agent.h"
class TSPAgent : public Agent {
public:
        TSPAgent();
protected:
        int command(int argc, const char*const* argv);
private:
        int    tsp_var1;
        double tsp_var2;
        void   TSPPrivFunc(void);
};

static class TSPAgentClass : public TclClass {
public:
       TSPAgentClass() : TclClass("Agent/TSPAgentOtcl") {}
        TclObject* create(int, const char*const*) {
                return(new TSPAgent());
        }
} class_tsp_agent;

TSPAgent::TSPAgent() : Agent(PT_UDP) {
       bind("tsp_var1_otcl", &tsp_var1);
       bind("tsp_var2_otcl", &tsp_var2);
}
int TSPAgent::command(int argc, const char*const* argv) {
      if(argc == 2) {
           if(strcmp(argv[1], "call-tsp-priv-func") == 0) {
                  TSPPrivFunc();
                  return(TCL_OK);
           }
      }
     return(Agent::command(argc, argv));
}

void TSPAgent::TSPPrivFunc(void) {
      Tcl& tcl = Tcl::instance();
      tcl.eval("puts \"Message From TSPPrivFunc\"");
      tcl.evalf("puts \"     Area of the Cylinder is = %f\"", tsp_var1*tsp_var2*2*3.14);
}

TCL Code to Test the above C++ Program (Agent)

# Create MyAgent (This will give two warning messages that
set myagent [new Agent/TSPAgentOtcl]

# Set configurable parameters of MyAgent
$myagent set tsp_var1_otcl 2
$myagent set tsp_var2_otcl 6.5

# Give a command to MyAgent
$myagent call-tsp-priv-func

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