Adding a New Agent and Application in Network Simulator 2 (NS2)

 This post is reproduced from this websitehttp://nile.wpi.edu/NS/new_app_agent.html.  But the above code is compiled for older ns2 version. But nsnam.com showcases the code for ns-2.35 version. You can read the theory about the agent from this weblink.
  
A Simple theory about Application and Agent
In Ns2, Nodes are individual entities where in...

Nodes -> Agent -> Application
Nodes is attached with an Agent and the Agent carries the Application. You can see the following image where Node is attached with the Agent and the Agent carries the FTP or CBR Application

Here is an Agent and Application is implemented
Agent - UDPmm
Application - mmApp

node -> Agent -> Application

To compile it 
Method 1: Easy method


Please download the code here

• Copy the mm-app.cc/.h and udp-mm.cc/.h in the -ns-2.35/multimedia directory
• there is another folder called ns-modified-files/folder, copy the files which are there in to the corresponding location as specified below (Replace the existing files, Also take backup of your old files)

Following Files are modified
-ns-2.35/common/packet.h
 -ns-2.35/common/agent.h
-ns-2.35/tcl/lib/ns-packet.tcl
-ns-2.35/tcl/lib/ns-default.tcl
-ns-2.35/apps/app.h
-ns-2.35/Makefile.in


Then from the ns-2.35/folder 
$] ./configure && make
Test the testmm.tcl file and see the output, you can create any tcl file with udpmm as an agent and mmapp as application layer. 

Method 2: For advanced users... 

1. Copy "mm-app.h", "mm-app.cc", "udp-mm.h" and "udp-mm.cc" to the "~ns-2.35/multimedia" directory.

2. Add the entry to Makefile.in as shown below

~ns-2.35/Makefile.in

OBJ_CC=

.....................

multimedia/mm-app.o multimedia/udp-mm.o \

3. Register the new application header by modifying "packet.h" (~ns-2.35/common/packet.h) and "ns-packet.tcl" (~ns-2.35/tcl/lib/ns-packet.tcl) as shown below.

Change the following lines to

// AOMDV packet

static const packet_t PT_AOMDV = 72;

// insert new packet types here

static packet_t PT_NTYPE = 73; // This MUST be the LAST one

// AOMDV packet

static const packet_t PT_AOMDV = 72;

static const packet_t PT_Multimedia = 73;

// insert new packet types here

static packet_t PT_NTYPE = 74; // This MUST be the LAST one

Change the following lines to

name_[PT_AOMDV]= "AOMDV";

name_[PT_NTYPE]= "undefined";

name_[PT_AOMDV]= "AOMDV";

name_[PT_Multimedia]="Multimedia";

name_[PT_NTYPE]= "undefined";

change the following lines in the ns-packet.tcl

# Other:

Encap # common/encap.cc

IPinIP # IP encapsulation

HDLC # High Level Data Link Control

# Other:

Encap # common/encap.cc

IPinIP # IP encapsulation

HDLC # High Level Data Link Control

Multimedia

4. Add supportMM() and enableMM() methods to the "Agent" class in "agent.h" (~ns-2.35/common/agent.h) as shown below.

Add the two yellow colored lines in agent.h in Agent Class

class Agent : public Connector {

public:

--------------------------

virtual void sendmsg(int sz, AppData*, const char* flags = 0);

virtual void send(int sz, AppData *data) { sendmsg(sz, data, 0); }

virtual int supportMM() { return 0; }

virtual void enableMM(){}

virtual void attachApp(Application* app);

virtual int& size() { return size_; }

5. Add recv_msg() method to the "Application" class in "app.h" (~ns-2.35/apps/app.h) as shown below.

Add the yellow line to app.h in Application Class.
class Application : public Process {

public:

Application();

virtual void send(int nbytes);

virtual void recv(int nbytes);

virtual void recv_msg(int nbytes, const char *msg=0){}

virtual void resume();

6. Set default values for the newly introduced configurable parameters in "ns-default.tcl" as shown below.

# There are five rates in which the application layer is supporting.. 

Application/MmApp set rate0_ 0.3mb

Application/MmApp set rate1_ 0.6mb

Application/MmApp set rate2_ 0.9mb

Application/MmApp set rate3_ 1.2mb

Application/MmApp set rate4_ 1.5mb

Application/MmApp set pktsize_ 1000

Application/MmApp set random_ false

7. Be SURE to complete this last step. Otherwise, all five-scale rates are initialized to zero unless specified in the input simulation script (i.e., the test simulation script given below will not transmit any frames).

8. Go to ns-2.35 using shell prompt and enter the commands

./configure

make

9. Run the file using “ns testmm.tcl” (this is to test your multimedia using applications) 
   
   
    Here is a sample output

   

   Multimedia Agent