建立总线型拓扑。

/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */

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#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

//

// 10.1.1.0

// n0 -------------- n1 n2 n3 n4

// point-to-point | | | |

// ================

// LAN 10.1.2.0

using namespace ns3;

NS_LOG_COMPONENT_DEFINE ("SecondScriptExample");

int

main (int argc, char *argv[])

{

//定义变量，用于决定是否开启2个UdpApplication的Logging组件；默认true开启。

bool verbose = true;

uint32_t nCsma = 3;//LAN有3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);

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****************************/

//创建使用P2P链路的2个node

NodeContainer p2pNodes;

p2pNodes.Create (2);

//创建另一个NodeContainer类对象，用于总线（CSMA）网络

NodeContainer csmaNodes;

csmaNodes.Add (p2pNodes.Get (1));

csmaNodes.Create (nCsma);//將之前P2P的NodeContainer的第二个节点（索引1）添加到CSMA的Nodeontainer，获得CSMA device；这个node将会有2个device

PointToPointHelper pointToPoint;

pointToPoint.SetDeviceAttribute ("DataRate", StringValue ("5Mbps"));

pointToPoint.SetChannelAttribute ("Delay", StringValue ("2ms"));

//安装P2P网卡设备到P2P网络节点，同first.cc

NetDeviceContainer p2pDevices;

p2pDevices = pointToPoint.Install (p2pNodes);

//类似于P2PHelper,CsmaHelper帮助创建和连接CSMA设备及信道

CsmaHelper csma;

csma.SetChannelAttribute ("DataRate", StringValue ("100Mbps"));

//数据率由channel属性指定，而非Device属性，因为CSMA不允许同一信道有多个不同数据率的设备。

csma.SetChannelAttribute ("Delay", TimeValue (NanoSeconds (6560)));

NetDeviceContainer csmaDevices;

csmaDevices = csma.Install (csmaNodes);

//安装网络协议

InternetStackHelper stack;

stack.Install (p2pNodes.Get (0));//P2P链路中的第一节点

stack.Install (csmaNodes);

//P2P链路中的第二节点包含在csmaNodes中。

Ipv4AddressHelper address;//2个网段的IP地址类对象

address.SetBase ("10.1.1.0", "255.255.255.0");//安排P2P网段的地址

Ipv4InterfaceContainer p2pInterfaces;

p2pInterfaces = address.Assign (p2pDevices);

address.SetBase ("10.1.2.0", "255.255.255.0");

Ipv4InterfaceContainer csmaInterfaces;

csmaInterfaces = address.Assign (csmaDevices);

/**************************网络拓扑部分结束****************************/

/**************************应用程序部分****************************/

UdpEchoServerHelper echoServer (9);

//將Server服务安装在CSMA网段的最后一个节点上，nCsma是可变的，所以不能用3.

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 (p2pNodes.Get (0));

clientApps.Start (Seconds (2.0));

clientApps.Stop (Seconds (10.0));

/**************************应用程序部分结束****************************/

/********************调用全局路由Helper帮助建立网络路由*********************/

Ipv4GlobalRoutingHelper::PopulateRoutingTables ();

//全局路由管理器根据节点产生的链路通告为每个节点建立路由表

pointToPoint.EnablePcapAll ("second");//second是前缀名，不用担心命名问题

csma.EnablePcap ("second", csmaDevices.Get (1), true);//开启csmahelper类对象的pcap

//Netevice不用取得ID，可以直接使用，但是Node需要进一步查找ID

Simulator::Run ();

Simulator::Destroy ();

return 0;

}

运行结果：

前面两个都是

后面一个是

由于要查找谁有该ip所以发送arp消息。

使用可视化：./waf --run second --vis