NS-3 源码修改--实现tcp数据包特征（大小和间隔）服从特定分布

NS-3源文件中包含有许多样例和说明文档，大家可以参考学习。针对本实验室需要完成工作的一部分，也就是源节点向目的节点发送Tcp数据包，数据包大小满足均匀分布，发包过程满足泊松分布（即发包间隔满足指数分布）的要求，没有现成的样例可以借鉴，思考之后，决定修改onoffapplication和OnOffHelper相关源码。

OnOffApplication类声明和实现中，PacketSize是一个常数，

.AddAttribute ("PacketSize", "The size of packets sent in on state",                 UintegerValue (512),                 MakeUintegerAccessor (&OnOffApplication::m_pktSize),                 MakeUintegerChecker<uint32_t> (1))

一旦设定，本次仿真无法更改；
而且也没有发包间隔Interval这一属性。
为不影响系统其他模块的使用，将涉及到onoffapplication类定义和声明的头文件，源文件全部拷贝进入一个.cc文件。包括onoff-application.h；onoff-application.cc；on-off helper.h；onoff helper.cc
相关类名之前加上前缀，如my,即类名分别为myOnOffApplication，myOnOffHelper。
新增变量：

Ptr<RandomVariableStream>  m_interval;    Ptr<RandomVariableStream>  m__packetsize;

myOnOffApplication类实现中，增加语句

.AddAttribute ("PacketSize", "The size of packets sent in on state",                   StringValue ("ns3::ConstantRandomVariable[Constant=137]"),                   MakePointerAccessor (&myOnOffApplication::m__packetsize),                   MakePointerChecker <RandomVariableStream>()).AddAttribute ("Interval", "The time between packets sent in on state",                   StringValue ("ns3::ConstantRandomVariable[Constant=1.0]"),                   MakePointerAccessor (&myOnOffApplication::m_interval),                   MakePointerChecker <RandomVariableStream>())

在成员函数myOnOffApplication::AssignStreams (int64_t stream)中添加语句

m_interval->SetStream (stream + 2);m__packetsize->SetStream (stream + 3);return 4;

在成员函数myOnOffApplication::ScheduleNextTx ()中添加语句

 m_pktSize=m__packetsize->GetValue();

来控制数据包大小；
添加语句

double myinterval=m_interval->GetValue();cout << "the interval is "<<myinterval<<endl;Time nextTime (Seconds (bits /                          static_cast<double>(m_cbrRate.GetBitRate ())+myinterval)); NS_LOG_LOGIC ("nextTime = " << nextTime);

之后只需修改OnOffHelper类名为myOnOffHelper即可。
关键是数据PacketSize和Interval格式的改变，将两者都定义为随机变量流。

统计数据包大小和发包间隔，利用Gnuplot画图如下


数据包大小在100-137字节之间均匀分布；
发包间隔为指数分布。

希望对大家的学习有所帮助！
可直接运行的源码如下：

#include <fstream>#include "ns3/gnuplot.h"#include "ns3/core-module.h"#include "ns3/network-module.h"#include "ns3/internet-module.h"#include "ns3/point-to-point-module.h"#include "ns3/applications-module.h"#include "ns3/random-variable-stream.h"#include "ns3/rng-seed-manager.h"#include <iostream>#include "ns3/gnuplot.h"#include "ns3/core-module.h"#include "ns3/network-module.h"#include "ns3/netanim-module.h"#include "ns3/internet-module.h"#include "ns3/point-to-point-module.h"#include "ns3/applications-module.h"#include "ns3/point-to-point-layout-module.h"#include "ns3/netanim-module.h"#include "ns3/address.h"#include "ns3/application.h"#include "ns3/event-id.h"#include "ns3/ptr.h"#include "ns3/data-rate.h"#include "ns3/traced-callback.h"#include "ns3/log.h"#include "ns3/address.h"#include "ns3/inet-socket-address.h"#include "ns3/inet6-socket-address.h"#include "ns3/packet-socket-address.h"#include "ns3/node.h"#include "ns3/nstime.h"#include "ns3/data-rate.h"#include "ns3/random-variable-stream.h"#include "ns3/socket.h"#include "ns3/simulator.h"#include "ns3/socket-factory.h"#include "ns3/packet.h"#include "ns3/uinteger.h"#include "ns3/trace-source-accessor.h"#include "ns3/onoff-application.h"#include "ns3/udp-socket-factory.h"#include "ns3/string.h"#include "ns3/pointer.h"#include "ns3/on-off-helper.h"#include "ns3/inet-socket-address.h"#include "ns3/packet-socket-address.h"#include "ns3/string.h"#include "ns3/data-rate.h"#include "ns3/uinteger.h"#include "ns3/names.h"#include "ns3/random-variable-stream.h"#include <stdint.h>#include <string>#include "ns3/object-factory.h"#include "ns3/address.h"#include "ns3/attribute.h"#include "ns3/net-device.h"#include "ns3/node-container.h"#include "ns3/application-container.h"#include "ns3/onoff-application.h"#include <fstream>#include "ns3/gnuplot.h"#include "algorithm"using namespace std;using namespace ns3;///////////////////////统计画图模块/////////// Gnuplot2dDataset dataset_interval2;std::string fileNameWithNoExtension = "uniform";std::string graphicsFileName        = fileNameWithNoExtension + ".png";std::string plotFileName            = fileNameWithNoExtension + ".plt";std::string plotTitle               = "packetsizes interval";std::string dataTitle               = "uniform-D Data";// Instantiate the plot and set its title.Gnuplot plot (graphicsFileName);Gnuplot2dDataset dataset_interval;/////////////////////////////////std::string fileNameWithNoExtension2 = "packetsize";std::string graphicsFileName2        = fileNameWithNoExtension2 + ".png";std::string plotFileName2            = fileNameWithNoExtension2 + ".plt";std::string plotTitle2               = "packetsizes ";  std::string dataTitle2               = "uniform-D Data";  // Instantiate the plot and set its title.  Gnuplot plot2 (graphicsFileName2);  Gnuplot2dDataset dataset_packetsize;//dataset_interval.SetTitle (dataTitle);  //dataset_interval.SetStyle (Gnuplot2dDataset::LINES_POINTS);  int count_packets=0;  double data_interval[48];  int    data_packetsize[48];////////////////////////////////////////////////////////////////////////// onoff-application .h  类声明namespace ns3 {class Address;class RandomVariableStream;class Socket;class myOnOffApplication : public Application{public:  /**   * \brief Get the type ID.   * \return the object TypeId   */  static TypeId GetTypeId (void);  myOnOffApplication ();  virtual ~myOnOffApplication();  /**   * \brief Set the total number of bytes to send.   *   * Once these bytes are sent, no packet is sent again, even in on state.   * The value zero means that there is no limit.   *   * \param maxBytes the total number of bytes to send   */  void SetMaxBytes (uint32_t maxBytes);  /**   * \brief Return a pointer to associated socket.   * \return pointer to associated socket   */  Ptr<Socket> GetSocket (void) const; /**  * \brief Assign a fixed random variable stream number to the random variables  * used by this model.  *  * \param stream first stream index to use  * \return the number of stream indices assigned by this model  */  int64_t AssignStreams (int64_t stream);protected:  virtual void DoDispose (void);private:  // inherited from Application base class.  virtual void StartApplication (void);    // Called at time specified by Start  virtual void StopApplication (void);     // Called at time specified by Stop  //helpers  /**   * \brief Cancel all pending events.   */  void CancelEvents ();   void StartSending ();  /**   * \brief Start an Off period   */  void StopSending ();  void SendPacket ();  Ptr<Socket>     m_socket;       //!< Associated socket  Address         m_peer;         //!< Peer address  bool            m_connected;    //!< True if connected  Ptr<RandomVariableStream>  m_onTime;       //!< rng for On Time  Ptr<RandomVariableStream>  m_offTime;      //!< rng for Off Time  Ptr<RandomVariableStream>  m_interval;      Ptr<RandomVariableStream>  m__packetsize;  DataRate        m_cbrRate;      //!< Rate that data is generated  DataRate        m_cbrRateFailSafe;      //!< Rate that data is generated (check copy)  uint32_t        m_pktSize;      //!< Size of packets  uint32_t        m_residualBits; //!< Number of generated, but not sent, bits  Time            m_lastStartTime; //!< Time last packet sent  uint32_t        m_maxBytes;     //!< Limit total number of bytes sent  uint32_t        m_totBytes;     //!< Total bytes sent so far  EventId         m_startStopEvent;     //!< Event id for next start or stop event  EventId         m_sendEvent;    //!< Event id of pending "send packet" event  TypeId          m_tid;          //!< Type of the socket used // int             count_packets;  /// Traced Callback: transmitted packets.  TracedCallback<Ptr<const Packet> > m_txTrace;private:  /**   * \brief Schedule the next packet transmission   */  void ScheduleNextTx ();  /**   * \brief Schedule the next On period start   */  void ScheduleStartEvent ();  /**   * \brief Schedule the next Off period start   */  void ScheduleStopEvent ();  void ConnectionSucceeded (Ptr<Socket> socket);  /**   * \brief Handle a Connection Failed event   * \param socket the not connected socket   */  void ConnectionFailed (Ptr<Socket> socket);};} // namespace ns3//////////////////////////////////////////////onoff-application.cc  类的实现 namespace ns3 {NS_LOG_COMPONENT_DEFINE ("myOnOffApplication");NS_OBJECT_ENSURE_REGISTERED (myOnOffApplication);TypeIdmyOnOffApplication::GetTypeId (void){  static TypeId tid = TypeId ("ns3::myOnOffApplication")    .SetParent<Application> ()    .SetGroupName("Applications")    .AddConstructor<myOnOffApplication> ()    .AddAttribute ("DataRate", "The data rate in on state.",                   DataRateValue (DataRate ("500kb/s")),                   MakeDataRateAccessor (&myOnOffApplication::m_cbrRate),                   MakeDataRateChecker ())    .AddAttribute ("PacketSize", "The size of packets sent in on state",                   StringValue ("ns3::ConstantRandomVariable[Constant=137]"),                   MakePointerAccessor (&myOnOffApplication::m__packetsize),                   MakePointerChecker <RandomVariableStream>())    .AddAttribute ("Interval", "The time between packets sent in on state",                   StringValue ("ns3::ConstantRandomVariable[Constant=1.0]"),                   MakePointerAccessor (&myOnOffApplication::m_interval),                   MakePointerChecker <RandomVariableStream>())    .AddAttribute ("Remote", "The address of the destination",                   AddressValue (),                   MakeAddressAccessor (&myOnOffApplication::m_peer),                   MakeAddressChecker ())    .AddAttribute ("OnTime", "A RandomVariableStream used to pick the duration of the 'On' state.",                   StringValue ("ns3::ConstantRandomVariable[Constant=1.0]"),                   MakePointerAccessor (&myOnOffApplication::m_onTime),                   MakePointerChecker <RandomVariableStream>())    .AddAttribute ("OffTime", "A RandomVariableStream used to pick the duration of the 'Off' state.",                   StringValue ("ns3::ConstantRandomVariable[Constant=1.0]"),                   MakePointerAccessor (&myOnOffApplication::m_offTime),                   MakePointerChecker <RandomVariableStream>())    .AddAttribute ("MaxBytes",                   "The total number of bytes to send. Once these bytes are sent, "                   "no packet is sent again, even in on state. The value zero means "                   "that there is no limit.",                   UintegerValue (0),                   MakeUintegerAccessor (&myOnOffApplication::m_maxBytes),                   MakeUintegerChecker<uint32_t> ())    .AddAttribute ("Protocol", "The type of protocol to use.",                   TypeIdValue (UdpSocketFactory::GetTypeId ()),                   MakeTypeIdAccessor (&myOnOffApplication::m_tid),                   MakeTypeIdChecker ())    .AddTraceSource ("Tx", "A new packet is created and is sent",                     MakeTraceSourceAccessor (&myOnOffApplication::m_txTrace),                     "ns3::Packet::TracedCallback")  ;  return tid;}myOnOffApplication::myOnOffApplication ()  : m_socket (0),    m_connected (false),    m_residualBits (0),    m_lastStartTime (Seconds (0)),   // count_packets(0),    m_totBytes (0){  NS_LOG_FUNCTION (this);}myOnOffApplication::~myOnOffApplication(){  NS_LOG_FUNCTION (this);}voidmyOnOffApplication::SetMaxBytes (uint32_t maxBytes){  NS_LOG_FUNCTION (this << maxBytes);  m_maxBytes = maxBytes;}Ptr<Socket>myOnOffApplication::GetSocket (void) const{  NS_LOG_FUNCTION (this);  return m_socket;}int64_tmyOnOffApplication::AssignStreams (int64_t stream){  NS_LOG_FUNCTION (this << stream);  m_onTime->SetStream (stream);  m_offTime->SetStream (stream + 1);  m_interval->SetStream (stream + 2);  m__packetsize->SetStream (stream + 3);  return 4;}voidmyOnOffApplication::DoDispose (void){  NS_LOG_FUNCTION (this);  m_socket = 0;  // chain up  Application::DoDispose ();}// Application Methodsvoid myOnOffApplication::StartApplication () // Called at time specified by Start{  NS_LOG_FUNCTION (this);  // Create the socket if not already  if (!m_socket)    {      m_socket = Socket::CreateSocket (GetNode (), m_tid);      if (Inet6SocketAddress::IsMatchingType (m_peer))        {          m_socket->Bind6 ();        }      else if (InetSocketAddress::IsMatchingType (m_peer) ||               PacketSocketAddress::IsMatchingType (m_peer))        {          m_socket->Bind ();        }      m_socket->Connect (m_peer);      m_socket->SetAllowBroadcast (true);      m_socket->ShutdownRecv ();      m_socket->SetConnectCallback (        MakeCallback (&myOnOffApplication::ConnectionSucceeded, this),        MakeCallback (&myOnOffApplication::ConnectionFailed, this));    }  m_cbrRateFailSafe = m_cbrRate;  // Insure no pending event  CancelEvents ();  // If we are not yet connected, there is nothing to do here  // The ConnectionComplete upcall will start timers at that time  //if (!m_connected) return;  ScheduleStartEvent ();}void myOnOffApplication::StopApplication () // Called at time specified by Stop{  NS_LOG_FUNCTION (this);  CancelEvents ();  if(m_socket != 0)    {      m_socket->Close ();    }  else    {      NS_LOG_WARN ("myOnOffApplication found null socket to close in StopApplication");    }}void myOnOffApplication::CancelEvents (){  NS_LOG_FUNCTION (this);  if (m_sendEvent.IsRunning () && m_cbrRateFailSafe == m_cbrRate )    { // Cancel the pending send packet event      // Calculate residual bits since last packet sent      Time delta (Simulator::Now () - m_lastStartTime);      int64x64_t bits = delta.To (Time::S) * m_cbrRate.GetBitRate ();      m_residualBits += bits.GetHigh ();    }  m_cbrRateFailSafe = m_cbrRate;  Simulator::Cancel (m_sendEvent);  Simulator::Cancel (m_startStopEvent);}// Event handlersvoid myOnOffApplication::StartSending (){  NS_LOG_FUNCTION (this);  m_lastStartTime = Simulator::Now ();  ScheduleNextTx ();  // Schedule the send packet event  ScheduleStopEvent ();}void myOnOffApplication::StopSending (){  NS_LOG_FUNCTION (this);  CancelEvents ();  ScheduleStartEvent ();}void myOnOffApplication::ScheduleNextTx (){  NS_LOG_FUNCTION (this);  if (m_maxBytes == 0 || m_totBytes < m_maxBytes)    {      cout<<"第几次进入 ScheduleNextTx ()"<<endl;        m_pktSize=m__packetsize->GetValue();   // 添加这一个数据包大小控制语句      data_packetsize[count_packets]=m_pktSize;      uint32_t bits = m_pktSize * 8 - m_residualBits;      NS_LOG_LOGIC ("bits = " << bits);      double myinterval=m_interval->GetValue();      cout << "the interval is "<<myinterval<<endl;           data_interval[count_packets]=myinterval;      count_packets++;     // dataset_interval.Add(count_packets,myinterval);      Time nextTime (Seconds (bits /                              static_cast<double>(m_cbrRate.GetBitRate ())+myinterval)); // Time till next packet      NS_LOG_LOGIC ("nextTime = " << nextTime);      m_sendEvent = Simulator::Schedule (nextTime,                                         &myOnOffApplication::SendPacket, this);    }  else    { // All done, cancel any pending events      StopApplication ();    }}void myOnOffApplication::ScheduleStartEvent (){  // Schedules the event to start sending data (switch to the "On" state)  NS_LOG_FUNCTION (this);  Time offInterval = Seconds (m_offTime->GetValue ());  NS_LOG_LOGIC ("start at " << offInterval);  m_startStopEvent = Simulator::Schedule (offInterval, &myOnOffApplication::StartSending, this);}void myOnOffApplication::ScheduleStopEvent (){  // Schedules the event to stop sending data (switch to "Off" state)  NS_LOG_FUNCTION (this);  Time onInterval = Seconds (m_onTime->GetValue ());  NS_LOG_LOGIC ("stop at " << onInterval);  m_startStopEvent = Simulator::Schedule (onInterval, &myOnOffApplication::StopSending, this);}void myOnOffApplication::SendPacket (){  NS_LOG_FUNCTION (this);  NS_ASSERT (m_sendEvent.IsExpired ());  Ptr<Packet> packet = Create<Packet> (m_pktSize);  m_txTrace (packet);  m_socket->Send (packet);  m_totBytes += m_pktSize;  if (InetSocketAddress::IsMatchingType (m_peer))    {      NS_LOG_INFO ("At time " << Simulator::Now ().GetSeconds ()                   << "s on-off application sent "                   <<  packet->GetSize () << " bytes to "                   << InetSocketAddress::ConvertFrom(m_peer).GetIpv4 ()                   << " port " << InetSocketAddress::ConvertFrom (m_peer).GetPort ()                   << " total Tx " << m_totBytes << " bytes");    }  else if (Inet6SocketAddress::IsMatchingType (m_peer))    {      NS_LOG_INFO ("At time " << Simulator::Now ().GetSeconds ()                   << "s on-off application sent "                   <<  packet->GetSize () << " bytes to "                   << Inet6SocketAddress::ConvertFrom(m_peer).GetIpv6 ()                   << " port " << Inet6SocketAddress::ConvertFrom (m_peer).GetPort ()                   << " total Tx " << m_totBytes << " bytes");    }  m_lastStartTime = Simulator::Now ();  m_residualBits = 0;  ScheduleNextTx ();}void myOnOffApplication::ConnectionSucceeded (Ptr<Socket> socket){  NS_LOG_FUNCTION (this << socket);  m_connected = true;}void myOnOffApplication::ConnectionFailed (Ptr<Socket> socket){  NS_LOG_FUNCTION (this << socket);}} // Namespace ns3//////////////////////// on-off helper .h   头文件namespace ns3 {class DataRate;/** * \ingroup onoff * \brief A helper to make it easier to instantiate an ns3::myOnOffApplication  * on a set of nodes. */class myOnOffHelper{public:  /**   * Create an myOnOffHelper to make it easier to work with myOnOffApplications   *   * \param protocol the name of the protocol to use to send traffic   *        by the applications. This string identifies the socket   *        factory type used to create sockets for the applications.   *        A typical value would be ns3::UdpSocketFactory.   * \param address the address of the remote node to send traffic   *        to.   */  myOnOffHelper (std::string protocol, Address address);  /**   * Helper function used to set the underlying application attributes.   *   * \param name the name of the application attribute to set   * \param value the value of the application attribute to set   */  void SetAttribute (std::string name, const AttributeValue &value);  /**   * Helper function to set a constant rate source.  Equivalent to   * setting the attributes OnTime to constant 1000 seconds, OffTime to    * constant 0 seconds, and the DataRate and PacketSize set accordingly   *   * \param dataRate DataRate object for the sending rate   * \param packetSize size in bytes of the packet payloads generated   */  void SetConstantRate (DataRate dataRate, uint32_t packetSize = 512);  /**   * Install an ns3::myOnOffApplication on each node of the input container   * configured with all the attributes set with SetAttribute.   *   * \param c NodeContainer of the set of nodes on which an myOnOffApplication    * will be installed.   * \returns Container of Ptr to the applications installed.   */  ApplicationContainer Install (NodeContainer c) const;  ApplicationContainer Install (Ptr<Node> node) const;  /**   * Install an ns3::myOnOffApplication on the node configured with all the    * attributes set with SetAttribute.   *   * \param nodeName The node on which an myOnOffApplication will be installed.   * \returns Container of Ptr to the applications installed.   */  ApplicationContainer Install (std::string nodeName) const; /**  * Assign a fixed random variable stream number to the random variables  * used by this model.  Return the number of streams (possibly zero) that  * have been assigned.  The Install() method should have previously been  * called by the user.  *  * \param stream first stream index to use  * \param c NodeContainer of the set of nodes for which the myOnOffApplication  *          should be modified to use a fixed stream  * \return the number of stream indices assigned by this helper  */  int64_t AssignStreams (NodeContainer c, int64_t stream);private:  /**   * Install an ns3::myOnOffApplication on the node configured with all the    * attributes set with SetAttribute.   *   * \param node The node on which an myOnOffApplication will be installed.   * \returns Ptr to the application installed.   */  Ptr<Application> InstallPriv (Ptr<Node> node) const;  ObjectFactory m_factory; //!< Object factory.};} // namespace ns3//////////////////////////////////  onoff helper.cc   实现    namespace ns3 {myOnOffHelper::myOnOffHelper (std::string protocol, Address address){  m_factory.SetTypeId ("ns3::myOnOffApplication");  m_factory.Set ("Protocol", StringValue (protocol));  m_factory.Set ("Remote", AddressValue (address));}voidmyOnOffHelper::SetAttribute (std::string name, const AttributeValue &value){  m_factory.Set (name, value);}ApplicationContainermyOnOffHelper::Install (Ptr<Node> node) const{  return ApplicationContainer (InstallPriv (node));}ApplicationContainermyOnOffHelper::Install (std::string nodeName) const{  Ptr<Node> node = Names::Find<Node> (nodeName);  return ApplicationContainer (InstallPriv (node));}ApplicationContainermyOnOffHelper::Install (NodeContainer c) const{  ApplicationContainer apps;  for (NodeContainer::Iterator i = c.Begin (); i != c.End (); ++i)    {      apps.Add (InstallPriv (*i));    }  return apps;}Ptr<Application>myOnOffHelper::InstallPriv (Ptr<Node> node) const{  Ptr<Application> app = m_factory.Create<Application> ();  node->AddApplication (app);  return app;}int64_tmyOnOffHelper::AssignStreams (NodeContainer c, int64_t stream){  int64_t currentStream = stream;  Ptr<Node> node;  for (NodeContainer::Iterator i = c.Begin (); i != c.End (); ++i)    {      node = (*i);      for (uint32_t j = 0; j < node->GetNApplications (); j++)        {          Ptr<myOnOffApplication> onoff = DynamicCast<myOnOffApplication> (node->GetApplication (j));          if (onoff)            {              currentStream += onoff->AssignStreams (currentStream);            }        }    }  return (currentStream - stream);}voidmyOnOffHelper::SetConstantRate (DataRate dataRate, uint32_t packetSize){  m_factory.Set ("OnTime", StringValue ("ns3::ConstantRandomVariable[Constant=1000]"));  m_factory.Set ("OffTime", StringValue ("ns3::ConstantRandomVariable[Constant=0]"));  m_factory.Set ("DataRate", DataRateValue (dataRate)); // m_factory.Set ("PacketSize", UintegerValue (packetSize));  m_factory.Set ("PacketSize",StringValue ("ns3::ConstantRandomVariable[Constant=532]"));  m_factory.Set ("Interval", StringValue ("ns3::ConstantRandomVariable[Constant=0.1]"));}} // namespace ns3//////////// Network topology//     n0--- -----n1using namespace ns3;//NS_LOG_COMPONENT_DEFINE ("tcp-one-point2one-point");intmain (int argc, char *argv[]){/*   ///////////////////////统计画图模块/////////  std::string fileNameWithNoExtension = "uniform";  std::string graphicsFileName        = fileNameWithNoExtension + ".png";  std::string plotFileName            = fileNameWithNoExtension + ".plt";  std::string plotTitle               = "2-D Plot";  std::string dataTitle               = "uniform-D Data";  // Instantiate the plot and set its title.  Gnuplot plot (graphicsFileName);  plot.SetTitle (plotTitle);  // Make the graphics file, which the plot file will create when it  // is used with Gnuplot, be a PNG file.  plot.SetTerminal ("png");  // Set the labels for each axis.  plot.SetLegend ("X Values", "Y Values");  // Set the range for the x axis.  plot.AppendExtra ("set xrange [1:+50]");  // Instantiate the dataset, set its title, and make the points be  // plotted along with connecting lines.  Gnuplot2dDataset dataset_interval;  dataset_interval.SetTitle (dataTitle);  dataset_interval.SetStyle (Gnuplot2dDataset::LINES_POINTS);////////////////////////////////////////////////////////////////////////  */   //  // Set up some default values for the simulation.  //    LogComponentEnable("myOnOffApplication",LOG_LEVEL_INFO);  // Config::SetDefault ("ns3::myOnOffApplication::PacketSize", UintegerValue (700));  // ??? try and stick 15kb/s into the data rate  Config::SetDefault ("ns3::myOnOffApplication::DataRate", StringValue ("50Mb/s"));  CommandLine cmd;  cmd.Parse (argc, argv);  NodeContainer nodes;  nodes.Create (2);    PointToPointHelper pointToPoint;  pointToPoint.SetDeviceAttribute ("DataRate", StringValue ("5Mbps"));  pointToPoint.SetChannelAttribute ("Delay", StringValue ("2ms"));  NetDeviceContainer devices;  devices=pointToPoint.Install (nodes);  //NS_LOG_INFO ("Install internet stack on all nodes.");  InternetStackHelper stack;  stack.Install (nodes); // NS_LOG_INFO ("Assign IP Addresses.");  Ipv4AddressHelper address;  address.SetBase ("10.1.1.0", "255.255.255.0");  Ipv4InterfaceContainer interfaces = address.Assign (devices);  //NS_LOG_INFO ("Create applications.");  //  // Create a packet sink on the star "hub" to receive packets.  //   uint16_t port = 50000;  Address hubLocalAddress (InetSocketAddress (Ipv4Address::GetAny (), port));  PacketSinkHelper packetSinkHelper ("ns3::TcpSocketFactory", hubLocalAddress);  ApplicationContainer hubApp = packetSinkHelper.Install (nodes.Get (1));       //接收端 n1 节点  hubApp.Start (Seconds (0.0));  hubApp.Stop (Seconds (200.0));  //  // Create OnOff applications to send TCP to the hub, one on each spoke node.  //  myOnOffHelper onOffHelper ("ns3::TcpSocketFactory", Address ());  onOffHelper.SetAttribute ("OnTime", StringValue ("ns3::ConstantRandomVariable[Constant=200]"));  onOffHelper.SetAttribute ("OffTime", StringValue ("ns3::ConstantRandomVariable[Constant=0]"));  onOffHelper.SetAttribute ("MaxBytes",UintegerValue(0) ); // onOffHelper.SetAttribute ("PacketSize", StringValue ("ns3::ConstantRandomVariable[Constant=137]"));   onOffHelper.SetAttribute ("PacketSize", StringValue ("ns3::UniformRandomVariable[Min=100|Max=137]"));  // onOffHelper.SetAttribute ("Interval", StringValue ("ns3::ConstantRandomVariable[Constant=2]"));  //onOffHelper.SetAttribute ("Interval", StringValue ("ns3::UniformRandomVariable[Min=1|Max=4]"));  onOffHelper.SetAttribute ("Interval", StringValue ("ns3::ExponentialRandomVariable[Mean=3.14|Bound=0.0]"));  ApplicationContainer spokeApps;  AddressValue remoteAddress (InetSocketAddress (interfaces.GetAddress(1), port));       //远端地址  也就是接收端的IP地址  onOffHelper.SetAttribute ("Remote", remoteAddress);  spokeApps.Add(onOffHelper.Install(nodes.Get(0)));  spokeApps.Start (Seconds (0.0));  spokeApps.Stop (Seconds (200.0));  //NS_LOG_INFO ("Enable static global routing.");  //  // Turn on global static routing so we can actually be routed across the star.  //  Ipv4GlobalRoutingHelper::PopulateRoutingTables ();  //NS_LOG_INFO ("Enable pcap tracing.");  //  // Do pcap tracing on all point-to-point devices on all nodes.  //  pointToPoint.EnablePcapAll ("one-point2one-point"); // NS_LOG_INFO ("Run Simulation."); // AnimationInterface anim ("one-point2one-point.xml");  //double x1=12;  //double y1=12;  //double x2=24;  //double y2=24;  AnimationInterface::SetConstantPosition (nodes.Get(0),12,12);  AnimationInterface::SetConstantPosition (nodes.Get(1),24,24);  AnimationInterface anim ("one-point2one-point.xml");  anim.EnablePacketMetadata(); ////////////画图 // Add the dataset to the plot.  plot.SetTitle (plotTitle);  // Make the graphics file, which the plot file will create when it  // is used with Gnuplot, be a PNG file.  plot.SetTerminal ("png");  // Set the labels for each axis.  plot.SetLegend ("X Values", "Y Values");  // Set the range for the x axis.  plot.AppendExtra ("set xrange [1:+50]"); /*  plot.AddDataset (dataset_interval);  // Open the plot file.  std::ofstream plotFile (plotFileName.c_str());  // Write the plot file.  plot.GenerateOutput (plotFile);  // Close the plot file.  plotFile.close(); */////////////////  Simulator::Run ();  sort(data_interval,data_interval+48);  for (int i=0;i<48;i++) {   dataset_interval.Add(i,data_interval[i]);   dataset_packetsize.Add(i,data_packetsize[i]); } //  dataset_interval.Add(count_packets,myinterval);  plot.AddDataset (dataset_interval);  // Open the plot file.  std::ofstream plotFile (plotFileName.c_str());  // Write the plot file.  plot.GenerateOutput (plotFile);  // Close the plot file.  plotFile.close();  //////////////////////  plot2.SetTitle (plotTitle2);  // Make the graphics file, which the plot file will create when it  // is used with Gnuplot, be a PNG file.  plot2.SetTerminal ("png");  // Set the labels for each axis.  plot2.SetLegend ("X Values", "Y Values");  // Set the range for the x axis.  plot2.AppendExtra ("set xrange [-5:+60]");  plot2.AppendExtra ("set yrange [60:+200]");  plot2.AddDataset (dataset_packetsize);  std::ofstream plotFile2 (plotFileName2.c_str());  // Write the plot file.  plot2.GenerateOutput (plotFile2);  // Close the plot file.  plotFile2.close();  Simulator::Destroy (); // NS_LOG_INFO ("Done.");  return 0;}