（四）NS3中示例：second.cc和third.cc程序的注释

（四）NS3中示例：second.cc和third.cc程序的注释

1. second.cc

#include "ns3/core-module.h"
#include "ns3/network-module.h"
#include "ns3/csma-module.h"
#include "ns3/internet-module.h"
#include "ns3/point-to-point-module.h"
#include "ns3/applications-module.h"
#include "ns3/ipv4-global-routing-helper.h"

// Default Network Topology拓扑分布
//
//       10.1.1.0
// n0 -------------- n1   n2   n3   n4
//    point-to-point  |    |    |    |
//                    ================
//                      LAN 10.1.2.0
//n0和n1实现点到点通信，n1~n4是个csma有线局域网。网络可以实现n0经由n1，和n4进行通信。

using namespace ns3;

NS_LOG_COMPONENT_DEFINE ("SecondScriptExample");//定义日志组件

int 
main (int argc, char *argv[])
{
  bool verbose = true;//定义bool变量用于决定是否开启日志组件，默认开启
  uint32_t nCsma = 3;//变量，用于定义csma网络中有多少个node

  CommandLine cmd;
  cmd.AddValue ("nCsma", "Number of \"extra\" CSMA nodes/devices", nCsma);
  cmd.AddValue ("verbose", "Tell echo applications to log if true", verbose);
//命令行参数，设置是否开启logging
  cmd.Parse (argc,argv);

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

  nCsma = nCsma == 0 ? 1 : nCsma;
//********网络拓扑部分********//
//p2p链路的两个节点创建
  NodeContainer p2pNodes;
  p2pNodes.Create (2);

  //创建csma网络节点
  NodeContainer csmaNodes;
  csmaNodes.Add (p2pNodes.Get (1));//将p2p节点1加到csma网络中
  csmaNodes.Create (nCsma);

  //设置p2p传输速率和信道延迟
  PointToPointHelper pointToPoint;
  pointToPoint.SetDeviceAttribute ("DataRate", StringValue ("5Mbps"));
  pointToPoint.SetChannelAttribute ("Delay", StringValue ("2ms"));
  //安装p2p网卡到p2p网络节点
  NetDeviceContainer p2pDevices;
  p2pDevices = pointToPoint.Install (p2pNodes);

  //设置csma传输速率和信道延迟，注意传输速率有channel指定，而非device属性。（CSMA不允许同一信道上有多个不同数据率的设备）
  CsmaHelper csma;
  csma.SetChannelAttribute ("DataRate", StringValue ("100Mbps"));
  csma.SetChannelAttribute ("Delay", TimeValue (NanoSeconds (6560)));

  NetDeviceContainer csmaDevices;
  csmaDevices = csma.Install (csmaNodes);
  //安装协议
  InternetStackHelper stack;
  stack.Install (p2pNodes.Get (0));//p2p的n0节点，n1节点在csma网络中安装协议栈
  stack.Install (csmaNodes);

  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);
  
  //********应用程序部分********//
  UdpEchoServerHelper echoServer (9);//服务器端口号
  //将server服务器安装在csma网络的n4节点。假定nCsma=3
  ApplicationContainer serverApps = echoServer.Install (csmaNodes.Get (nCsma));
  serverApps.Start (Seconds (1.0));
  serverApps.Stop (Seconds (10.0));

  UdpEchoClientHelper echoClient (csmaInterfaces.GetAddress (nCsma), 9);//设定远程服务器的IP地址和端口号
  echoClient.SetAttribute ("MaxPackets", UintegerValue (1));
  echoClient.SetAttribute ("Interval", TimeValue (Seconds (1.0)));
  echoClient.SetAttribute ("PacketSize", UintegerValue (1024));

  ApplicationContainer clientApps = echoClient.Install (p2pNodes.Get (0));
  clientApps.Start (Seconds (2.0));
  clientApps.Stop (Seconds (10.0));
  
  //********建立网络路由********//
  Ipv4GlobalRoutingHelper::PopulateRoutingTables ();
  
  //********开启pcap追踪********//
  //开启p2pHelper,csmaHelper类对象的pcap
  pointToPoint.EnablePcapAll ("second");
  csma.EnablePcap ("second", csmaDevices.Get (1), true);

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

2. third.cc

#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"
#include "ns3/mobility-module.h"
#include "ns3/csma-module.h"
#include "ns3/internet-module.h"

// Default Network Topology网络拓扑
//
//   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
//n0,n5-n7:wifi网络，n0为AP，n5,n6,n7为无线STA； n0和n1：p2p通信； n1-n4：csma网络。示例中实现了节点n7和n4通信。

using namespace ns3;

NS_LOG_COMPONENT_DEFINE ("ThirdScriptExample");

int 
main (int argc, char *argv[])
{
  bool verbose = true;//用于是否启用logging组件
  uint32_t nCsma = 3;//设置nCsma和nWifi的额外STA个数
  uint32_t nWifi = 3;

  CommandLine cmd;
  cmd.AddValue ("nCsma", "Number of \"extra\" CSMA nodes/devices", nCsma);
  cmd.AddValue ("nWifi", "Number of wifi STA devices", nWifi);
  cmd.AddValue ("verbose", "Tell echo applications to log if true", verbose);
  

  cmd.Parse (argc,argv);

  if (nWifi > 18)
    {
      std::cout << "Number of wifi nodes " << nWifi << 
                   " specified exceeds the mobility bounding box" << std::endl;
      exit (1);
    }

  if (verbose)
    {
      LogComponentEnable ("UdpEchoClientApplication", LOG_LEVEL_INFO);
      LogComponentEnable ("UdpEchoServerApplication", LOG_LEVEL_INFO);
    }
 //创建p2p链路2个节点
  NodeContainer p2pNodes;
  p2pNodes.Create (2);

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

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

  //创建csma网络的4个节点。默认nCsma=3
  NodeContainer csmaNodes;
  csmaNodes.Add (p2pNodes.Get (1));
  csmaNodes.Create (nCsma);

  CsmaHelper csma;
  csma.SetChannelAttribute ("DataRate", StringValue ("100Mbps"));
  csma.SetChannelAttribute ("Delay", TimeValue (NanoSeconds (6560)));

  NetDeviceContainer csmaDevices;
  csmaDevices = csma.Install (csmaNodes);
  
  //*********创建wifi网络的4个节点，默认STA=3；**********//
  NodeContainer wifiStaNodes;
  wifiStaNodes.Create (nWifi);//创建STA
  NodeContainer wifiApNode = p2pNodes.Get (0);//设置wifi的AP

  //配置PHY和Channel通道助手
  YansWifiChannelHelper channel = YansWifiChannelHelper::Default ();
  YansWifiPhyHelper phy = YansWifiPhyHelper::Default ();
  phy.SetChannel (channel.Create ());//Channel对象与PHY对象关联

  //MAC层配置==============================
  WifiHelper wifi = WifiHelper::Default ();
  wifi.SetRemoteStationManager ("ns3::AarfWifiManager");//使用AARF速率控制算法

  NqosWifiMacHelper mac = NqosWifiMacHelper::Default ();//non-Qos的MAC
  //配置wifi网络STA网络设备的MAC类型和基础设施网络的SSID
  Ssid ssid = Ssid ("ns-3-ssid");//IEEE 802.1服务集标识符对象
  mac.SetType ("ns3::StaWifiMac", //设置为特定种类MAC层，non-AP
               "Ssid", SsidValue (ssid),//设置SSID
               "ActiveProbing", BooleanValue (false));//设置ActiveProbing,false意味着助手创建的mac将不会发送探测请求。

  NetDeviceContainer staDevices;//STA 网络设备
  staDevices = wifi.Install (phy, mac, wifiStaNodes);//wifi的STA安装PHY层和MAC层
  
  //配置wifi网络AP网络设备的MAC类型和基础设施网络的SSID
  mac.SetType ("ns3::ApWifiMac",
               "Ssid", SsidValue (ssid));

  NetDeviceContainer apDevices;
  apDevices = wifi.Install (phy, mac, wifiApNode);//与STA共同的PHY特性
  
  //********移动模型********//
  MobilityHelper mobility;

  mobility.SetPositionAllocator ("ns3::GridPositionAllocator", //网格位置分配器
                                 "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", //以随机游走的方式移动
                             "Bounds", RectangleValue (Rectangle (-50, 50, -50, 50)));
  mobility.Install (wifiStaNodes); //安装到wifi网络的STA

  mobility.SetMobilityModel ("ns3::ConstantPositionMobilityModel");
  mobility.Install (wifiApNode);//安装到wifi网络的AP

  //安装协议栈
  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);
  
  //安装应用
  UdpEchoServerHelper echoServer (9);

  ApplicationContainer serverApps = echoServer.Install (csmaNodes.Get (nCsma));//csma网络的最后节点作为服务器
  serverApps.Start (Seconds (1.0));
  serverApps.Stop (Seconds (10.0));

  UdpEchoClientHelper echoClient (csmaInterfaces.GetAddress (nCsma), 9);//设置客户机的远程服务器IP地址和端口号
  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));//在随后建立的wifi STA上安装客户机
  clientApps.Start (Seconds (2.0));
  clientApps.Stop (Seconds (10.0));

  //建立网络路由
  Ipv4GlobalRoutingHelper::PopulateRoutingTables ();

  Simulator::Stop (Seconds (10.0));//无线接入点会一直产生信标，模拟器时间列表一直非空，仿真无法结束
  //
  pointToPoint.EnablePcapAll ("third");
  phy.EnablePcap ("third", apDevices.Get (0));
  csma.EnablePcap ("third", csmaDevices.Get (0), true);

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

参考文献：

[1] ns-3project. ns-3 Software Tutorial. ns-3 project. 2015年2月26日

[2]《ns-3网络模拟器基础及应用》，人民邮电出版社，马春光 姚建盛，2014年1月

部分参考网络资料，未一一列举，敬请原谅！