[C++知识库]NS-3——学习（3）

ns3中third.cc学习，它模拟了一个包括点对点和CSMA的有线网络，以及WIFI无线网络的混合场景。
网络拓扑示意图：

//头文件
#include "ns3/core-module.h"
#include "ns3/point-to-point-module.h"
#include "ns3/network-module.h"
#include "ns3/applications-module.h"
#include "ns3/wifi-module.h"           //WIFI模块
#include "ns3/mobility-module.h"      //移动模块
#include "ns3/csma-module.h"         //CSMA模块
#include "ns3/internet-module.h"

// Default Network Topology
//
//   Wifi 10.1.3.0
//                 AP
//  *    *    *    *
//  |    |    |    |    10.1.1.0
// n5   n6   n7   n0 -------------- n1   n2   n3   n4
//                   point-to-point  |    |    |    |
//                                   ================
//                                     LAN 10.1.2.0

using namespace ns3;//声明命名空间

NS_LOG_COMPONENT_DEFINE ("ThirdScriptExample");

int main (int argc, char *argv[])
{
  bool verbose = true;
  uint32_t nCsma = 3;
  uint32_t nWifi = 3;
  bool tracing = false;

  CommandLine cmd;
  cmd.AddValue ("nCsma", "Number of \"extra\" CSMA nodes/devices", nCsma);
  cmd.AddValue ("nWifi", "Number of wifi STA devices", nWifi);
  //读取命令行参数，“nWifi”参数控制脚本中的无线节点数量。数值可以在waf命令中设置。
  //./waf --run "third --n WiFi=18"    //无线节点数量18
  cmd.AddValue ("verbose", "Tell echo applications to log if true", verbose);
  cmd.AddValue ("tracing", "Enable pcap tracing", tracing);

  cmd.Parse (argc,argv);

  // The underlying restriction of 18 is due to the grid position
  // allocator's configuration; the grid layout will exceed the
  // bounding box if more than 18 nodes are provided.
  if (nWifi > 18)
    {
      std::cout << "nWifi should be 18 or less; otherwise grid layout exceeds the bounding box" << std::endl;
      return 1;
    }

  if (verbose)
    {
      LogComponentEnable ("UdpEchoClientApplication", LOG_LEVEL_INFO);
      LogComponentEnable ("UdpEchoServerApplication", LOG_LEVEL_INFO);
    }

点对点网络：

  NodeContainer p2pNodes;
  p2pNodes.Create (2);

  PointToPointHelper pointToPoint;
  pointToPoint.SetDeviceAttribute ("DataRate", StringValue ("5Mbps"));
  pointToPoint.SetChannelAttribute ("Delay", StringValue ("2ms"));

  NetDeviceContainer p2pDevices;
  p2pDevices = pointToPoint.Install (p2pNodes);

CSMA网络：

//声明NodeContainer放置已经成为CSMA网络的一部分节点，在点到点的结点容器中得到第一结点，把它加入到CSMA设备的结点容器中，在建立一些“多余的”结点
  NodeContainer csmaNodes;
  csmaNodes.Add (p2pNodes.Get (1));//双接口结点
  csmaNodes.Create (nCsma);//创建CSMA网络节点

  CsmaHelper csma;//CSMA助手类
  //设置CSMA信道属性：传输速率为100Mbps，传播延迟6560ns
  csma.SetChannelAttribute ("DataRate", StringValue ("100Mbps"));
  csma.SetChannelAttribute ("Delay", TimeValue (NanoSeconds (6560)));

  NetDeviceContainer csmaDevices;
  csmaDevices = csma.Install (csmaNodes);//连接结点与信道，在节点中设置网络设备

WiFi网络：（由一个接入点和nWiFi个移动节点组成）

//接下来创建的节点会成为无线网络的一部分，创建多个命令行参数指定的“站”节点，使用点对点链路“最左边”节点作为接入点。
  NodeContainer wifiStaNodes;
  wifiStaNodes.Create (nWifi);
  NodeContainer wifiApNode = p2pNodes.Get (0);
  //设置Channel和WiFiPhy
//默认传播延迟模型，损耗模型，误码率模型
  YansWifiChannelHelper channel = YansWifiChannelHelper::Default ();
  YansWifiPhyHelper phy = YansWifiPhyHelper::Default ();
  phy.SetChannel (channel.Create ());

//设置WiFiMac并在结点中安装NetDevice
  WifiHelper wifi;
  wifi.SetRemoteStationManager ("ns3::AarfWifiManager");

  WifiMacHelper mac;
  Ssid ssid = Ssid ("ns-3-ssid");
  mac.SetType ("ns3::StaWifiMac",     //移动节点
               "Ssid", SsidValue (ssid),
               "ActiveProbing", BooleanValue (false));

  NetDeviceContainer staDevices;//安装移动节点
  staDevices = wifi.Install (phy, mac, wifiStaNodes);

  mac.SetType ("ns3::ApWifiMac",//AP结点
               "Ssid", SsidValue (ssid));

  NetDeviceContainer apDevices;//安装AP结点
  apDevices = wifi.Install (phy, mac, wifiApNode);

  MobilityHelper mobility;
//为移动节点设置移动模型
  mobility.SetPositionAllocator ("ns3::GridPositionAllocator",
                                 "MinX", DoubleValue (0.0),
                                 "MinY", DoubleValue (0.0),
                                 "DeltaX", DoubleValue (5.0),
                                 "DeltaY", DoubleValue (10.0),
                                 "GridWidth", UintegerValue (3),
                                 "LayoutType", StringValue ("RowFirst"));

  mobility.SetMobilityModel ("ns3::RandomWalk2dMobilityModel",
                             "Bounds", RectangleValue (Rectangle (-50, 50, -50, 50)));
  mobility.Install (wifiStaNodes);
//设置移动模型
  mobility.SetMobilityModel ("ns3::ConstantPositionMobilityModel");
  mobility.Install (wifiApNode);

  InternetStackHelper stack;
  stack.Install (csmaNodes);
  stack.Install (wifiApNode);
  stack.Install (wifiStaNodes);

  Ipv4AddressHelper address;

  address.SetBase ("10.1.1.0", "255.255.255.0");
  Ipv4InterfaceContainer p2pInterfaces;
  p2pInterfaces = address.Assign (p2pDevices);

  address.SetBase ("10.1.2.0", "255.255.255.0");
  Ipv4InterfaceContainer csmaInterfaces;
  csmaInterfaces = address.Assign (csmaDevices);

  address.SetBase ("10.1.3.0", "255.255.255.0");
  address.Assign (staDevices);
  address.Assign (apDevices);

  UdpEchoServerHelper echoServer (9);

  ApplicationContainer serverApps = echoServer.Install (csmaNodes.Get (nCsma));
  serverApps.Start (Seconds (1.0));
  serverApps.Stop (Seconds (10.0));

  UdpEchoClientHelper echoClient (csmaInterfaces.GetAddress (nCsma), 9);
  echoClient.SetAttribute ("MaxPackets", UintegerValue (1));
  echoClient.SetAttribute ("Interval", TimeValue (Seconds (1.0)));
  echoClient.SetAttribute ("PacketSize", UintegerValue (1024));

  ApplicationContainer clientApps = 
    echoClient.Install (wifiStaNodes.Get (nWifi - 1));
  clientApps.Start (Seconds (2.0));
  clientApps.Stop (Seconds (10.0));

  Ipv4GlobalRoutingHelper::PopulateRoutingTables ();

  Simulator::Stop (Seconds (10.0));

  if (tracing == true)   //将上文的tracing设置为true可生成跟踪文件
    {
      pointToPoint.EnablePcapAll ("third");
      phy.EnablePcap ("third", apDevices.Get (0));
      csma.EnablePcap ("third", csmaDevices.Get (0), true);
    }

  Simulator::Run ();
  Simulator::Destroy ();
  return 0;
}

模拟运行结果：

可产生.pcap跟踪文件，third-0-0.pcap,third-0-1.pcap,third-1-0.pcap,third-1-1.pcap
例如：

NetAnim仿真