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Introduction to OMNeT++

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Introduction to OMNeT++ IDE, Part -1

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Introduction to OMNeT++

  1. 1. Introduction to OMNet++ Prepared by Md. Mahedee Hasan M.Sc Engg. IICT, BUET Web: http://mahedee.net Reviewed by Amit Karmaker Md. Abir Hossain M.Sc Engg. IICT, BUET Supervised by Dr. Mohammad Shah Alam Assistant Professor IICT, BUET Contents What is OMNeT++?.......................................................................................................................................2 Modeling concepts........................................................................................................................................2 Module..........................................................................................................................................................3 Message, gets and links ................................................................................................................................3 Parameters....................................................................................................................................................3 Classes that are part of simulation class library ...........................................................................................4 OMNeT++ Consists of....................................................................................................................................4 How OMNeT++ Works? ................................................................................................................................4 NED Features ................................................................................................................................................5 The Network .................................................................................................................................................5 .ini (Initialization) Files..................................................................................................................................6 .cc (C++) Files.................................................................................................................................................7 Channel .........................................................................................................................................................7 Simple and Compound Module ....................................................................................................................8
  2. 2. Simple Module............................................................................................................................................10 Compound Modules ...................................................................................................................................11 Channels......................................................................................................................................................12 Parameter ...................................................................................................................................................12 Gates...........................................................................................................................................................14 Sub Modules ...............................................................................................................................................15 Connections ................................................................................................................................................16 Inheritance..................................................................................................................................................16 Packages......................................................................................................................................................16 Create First Simulation Project using OMNeT++ ........................................................................................17 References ..................................................................................................................................................26 History Card ................................................................................................................................................26 What is OMNeT++?  OMNeT++ is a Simulator  For discrete event network  It is object oriented and modular  Used to simulate o Modeling of wired and wireless communication networks o Protocol modeling o Modeling of queuing networks etc.  Modules are connected using gates to form compound module o In other system sometimes gates are called port Modeling concepts  Modules are communicate with message passing  Active modules are called simple modules  Message are sent through output gates and receive through input gates  Input and output gates are linked through connection  Parameters such as propagation delay, data rate and bit error rate, can be assigned to connections
  3. 3. Fig – simple and compound module Module  In hierarchical module, the top level module is system module  System module contains sub modules  Sub modules contains sub modules themselves  Both simple and compound modules are instance of module type Message, gets and links  Module communicate by exchanging message  Message can represent frames or packets  Gates are the input and output interface of modules  Two sub modules can be connected by links with gates  Links = connections  Connections support the following parameter o Data rate, propagation delay, bit error rate, packet error rate Parameters  Modules parameters can be assigned o in either the NED files or o the configuration file omnetpp.ini.  Parameter can take string, numeric or Boolean data values or can contains XML data trees
  4. 4. Classes that are part of simulation class library The following classes are the part of simulation class library  Module, gates, parameter, channel  Message, packet  Container class (e.g. queue and array)  Data collection classes  Statistics and distribution estimated classes  Transition and result accuracy detection classes. OMNeT++ Consists of  NED language topology description(s)(.ned files)  Message definitions (.msg files)  Simple module sources. They are C++ files, with .h/.cc suffix. How OMNeT++ Works?  When Program started o Read all NED files containing model topology o Then it reads a configuration file(usually called omnetpp.ini)  Output is written in result file  Graph is generated from result file using Matlab, Phython etc
  5. 5. NED Features NED has several features which makes it scale well to large project  Hierarchical  Component-based  Interfaces  Inheritance  Packages  Metadata annotation The Network  Network consists of o Nodes o Gates and o Connections Fig: The network
  6. 6. network Network { submodules: node1 : Node; node2 : Node; node3 : Node; ……………………… connections: node1.port++<-->{datarate=100Mbps;}<-->node2.port++; node2.port++<-->{datarate=100Mbps;}<-->node3.port++; node3.port++<-->{datarate=100Mbps;}<-->node1.port++; ……………………… }  The double arrow means bi-directional connection  The connection points of the modules are called gates  The port++ notation adds a new gate to the port[] gate vector  Nodes are connected with a channel  Specify the network option in to the configuration like below [General] network = Network .ini (Initialization) Files  Defines the network initialization point with/without some parameters [General] network = TicToc1
  7. 7. .cc (C++) Files  Contains class definition and function for modules. #include <string.h> #include <omnetpp.h> class Txc1 : public cSimpleModule { protected: virtual void initialize(); virtual void handleMessage(cMessage *msg); }; Define_Module(Txc1); void Txc1::initialize() { // Am I Tic or Toc? if (strcmp("tic", getName()) == 0) { cMessage *msg = new cMessage("tictocMsg"); send(msg, "out"); } } void Txc1::handleMessage(cMessage *msg) { send(msg, "out"); } Channel  Predefined Channel type o IdealChannel o DelayChannel  delay (double with s, ms, us)  diabled (boolean) o DatarateChannel  delay (double with s, ms, us)  disabled (boolean)  datarate (double with unit as bps, kbps, Mbps, Gbps)  ber (double bit error rate [0,1])  per (double packet error rate [0,1])  One can create new channel type
  8. 8. network net { @display("bgb=340,233"); types: channel customChannel extends ned.DatarateChannel{ datarate=100Mbps; } submodules: computer1: computer { @display("p=63,55"); } computer2: computer { @display("p=260,55"); } connections: computer1.out -->customChannel--> computer2.in; computer2.out -->customChannel--> computer1.in; } Simple and Compound Module  Simple module is a basic building block  Denoted by simple keyword simple App { parameters: int destAddress; ... @display("i=block/browser"); gates: input in; output out; } simple Routing { ... } simple Queue { ... }  Convention : Module name should be Pascal case  Simple module combines into compound module
  9. 9. simple App { parameters: int destAddress; @display("i=block/browser"); gates: input in; output out; } simple Routing { gates: input localIn; output localOut; } simple Queue { gates: input in; output out; } module Node { parameters: int address; @display("i=misc/node_vs,gold"); gates: inout port[]; submodules: app: App; routing: Routing; queue[sizeof(port)]: Queue; connections: routing.localOut --> app.in; routing.localIn <-- app.out; for i=0..sizeof(port)-1 { routing.out[i] --> queue[i].in; routing.in[i] <-- queue[i].out; queue[i].line <--> port[i]; } }
  10. 10. Fig – The node compound module  When simulation program started its load NED file first.  Then it load corresponding simple module written in C++ such as App, Queue Simple Module  Simple module is the active component defined by simple keyword simple Queue { parameters: int capacity; @display("i=block/queue"); gates: input in; output out; }  Parameters and gates sections are optional here  Parameters keywords is optional too, parameters can be defined without parameters keyword  One can explicitly specify the C++ class with the @class property simple Queue { parameters: int capacity; @class(mylib::Queue); @display("i=block/queue"); gates: input in; output out; }
  11. 11.  The C++ classes will be mylib::App, mylib::Router and mylib::Queue @namespace(mylib); simple App{ ... } simple Router{ ... } simple Queue{ ... } Compound Modules  Groups other modules into a larger unit  A compound modules may have gates and parameters like simple module but not active  A compound modules may have several sections all of them optional module Host { types: ... parameters: ... gates: ... submodules: ... connections: ... }  Modules contains in compound module are called sub module – are in sub module section  Compound module may be inherited via sub classing module WirelessHost extends WirelessHostBase { submodules: webAgent:WebAgent; connections: webAgent.tcpOut-->tcp.appIn++; webAgent.tcpIn<--tcp.appOut++; } module DesktopHost extends WirelessHost { gates: inout ethg; submodules:
  12. 12. eth:EthernetNic; connections: ip.nicOut++-->eth.ipIn; ip.nicIn++<--eth.ipOut; eth.phy<-->ethg; } Channels  Channels are connections between nodes  Predefined channel types are: ned.IdealChannel, ned.DelayChannel and ned.DatarateChannel  Can use import ned.* channel Ethernet100 extends ned.DatarateChannel { datarate = 100Mbps; delay = 100us; ber = 1e-10; } Or channel DatarateChannel2 extends ned.DatarateChannel { double distance @unit(m); // @unit is a property delay = this.distance/200000km * 1s; } Parameter  Parameters are variables that belong to a module.  Parameters can be used in building the topology (number of nodes, etc)  To supply input to C++ code that implements simple modules and channels  For the numeric types, a unit of measurement can also be specified (@unit property), to increase type safety.  Parameters can get their values from NED files or from the configuration(Omnetpp.ini)
  13. 13. simple App { parameters: string protocol; //protocoltouse:"UDP"/"IP"/"ICMP"/... int destAddress; //destinationaddress volatile double sendInterval@unit(s)= default(exponential(1s)); //timebetweengeneratingpackets volatile int packetLength@unit(byte)= default(100B); //lengthofonepacket volatile int timeToLive= default(32); //maximumnumberofnetworkhopstosurvive gates: input in; output out; } Assigning a Value Another example  * matches any index  .. matches ranges  If number of individual hosts instead of a sub module vector, network definition can be like this:
  14. 14. Example: Gates  Connection points of Module  OMNeT++ has three types of gates o Input, output and inout Example 1:
  15. 15. Example 2: Example 3:  Gates around the edges of the grid are expected to remain unconnected, hence the @loose annotation used. Sub Modules  Modules that a compound module is composed of are called its sub modules.  A sub module has a name, and it is an instance of a compound or simple module type. Example:
  16. 16. Connections  Connections are defined in connections section in compound module Inheritance  In NED, a type may only extend an element of the same component type  A simple module may only extend a simple module, compound module may only extend a compound module, and so on.  Single inheritance is supported for modules and channels  Multiple inheritance is supported for module interfaces and channel interfaces  Inheritance may: o Add new properties, parameters, gates, inner types, sub modules, connections, as long as names do not conflict with inherited names o Modify inherited properties, and properties of inherited parameters and gates Packages  Group together similar modules  Reduces name conflicts  Before use the class, must reference the package
  17. 17. Create First Simulation Project using OMNeT++ Step 1: Create a OMNeT++ Project Go to File -> New -> OMNeT++ Project Step 2: Type project Name Type project Name (ex. FirstSim) in Project Name text box
  18. 18. Step 3: Add Initial Contents Here I add Empty project Step 4: Choose C++ Project Type Here we choose OMNeT++ simulation
  19. 19. Step 5: Select Configuration Step 6: Create NED File File -> New -> Network Description file (NED)
  20. 20. Step 7: Select Project for the NED file Step 8: Choose initial content for NED file
  21. 21. Step 9: Click finish Step 10: Modify and add the code below to source of ned file // // TODO documentation // simple computer { gates: input in; output out; } // // TODO documentation // network net { @display("bgb=340,233"); submodules: computer1: computer { @display("p=63,55"); } computer2: computer { @display("p=260,55"); } connections: computer1.out --> computer2.in; computer2.out --> computer1.in; } Step 11: Modify the source of Package.ned //package firstsim; // //@license(LGPL); @license(omnetpp);
  22. 22. Step 12: Create Initialization File (ini) Step 13: Choose project for ini file
  23. 23. Step 14: Choose initial content for ini file Step 15: Choose ned file for ini file
  24. 24. Step 16: Click finish Step 17: Create a C++ source file File->New->Source File Step 18: Type name of the C++ File (example: computer.cc)
  25. 25. Step 19: Modify the computer.cc /* * computer.cc * * Created on: Aug 25, 2015 * Author: mahedee */ #include<string.h> #include<omnetpp.h> /*computer is a simple module. A simple module is nothing more than a C++ class which has to be sub classed from cSimpleModule,with one or more virtual member functions redefined to define its behavior.*/ class computer : public cSimpleModule { protected: virtual void initialize(); virtual void handleMessage(cMessage *msg); }; /* The class has to be registered with OMNeT++ via the Define_Module() macro.The Define_Module() line should always be put into .cc or .cpp file and not header file (.h), because the compiler generates code from it. */ Define_Module(computer); void computer :: initialize() { if(strcmp("computer1",getName())==0) { cMessage *msg = new cMessage("checkMsg"); send(msg,"out"); } } void computer::handleMessage(cMessage *msg) { send(msg,"out"); } Now build the project, if it succeed then run the project. Mission complete..
  26. 26. References 1. OMNeT++ User Manual – Version 4.4 2. OMNeT++ User Guide – Version 4.4 3. OMNeT++ Video Tutorial 4. Stack Overflow 5. A Quick Overview of OMNeT++ IDE History Card Version Description Update Date Published Date 1 Draft Preparation 14 Aug 2015 2

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