ns3 如何创建自定义点对点拓扑

Question

创建点对点拓扑涉及两个节点，生成此类拓扑的代码如下：

// Default Network Topology
//
//       10.1.1.0
// n0 -------------- n1
//    point-to-point
//
 
using namespace ns3;

NS_LOG_COMPONENT_DEFINE ("FirstScriptExample");

int
main (int argc, char *argv[])
{
  CommandLine cmd (__FILE__);
  cmd.Parse (argc, argv);
  
  Time::SetResolution (Time::NS);
  LogComponentEnable ("UdpEchoClientApplication", LOG_LEVEL_INFO);
  LogComponentEnable ("UdpEchoServerApplication", LOG_LEVEL_INFO);

  NodeContainer nodes;
  nodes.Create (2);

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

  NetDeviceContainer devices;
  devices = pointToPoint.Install (nodes);

  InternetStackHelper stack;
  stack.Install (nodes);

  Ipv4AddressHelper address;
  address.SetBase ("10.1.1.0", "255.255.255.0");

  Ipv4InterfaceContainer interfaces = address.Assign (devices);

  UdpEchoServerHelper echoServer (9);

  ApplicationContainer serverApps = echoServer.Install (nodes.Get (1));
  serverApps.Start (Seconds (1.0));
  serverApps.Stop (Seconds (10.0));

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

  ApplicationContainer clientApps = echoClient.Install (nodes.Get (0));
  clientApps.Start (Seconds (2.0));
  clientApps.Stop (Seconds (10.0));

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

这段代码只创建了两个点对点节点。 但是我们如何创建一个具有超过 2 个节点的点对点拓扑，如下图：

Answer 1

有several layout helpers for PointToPointNetDevices，但没有一个完全符合您的目标。

实现所需拓扑的最直接方法是创建节点，然后手动安装 PointToPointNetDevices。类似于

NodeContainer nodes(7);
PointToPointHelper pointToPoint;
NetDeviceContainer devices;

devices.Add(pointToPoint.Install(nodes.Get(0), nodes.Get(1)));
devices.Add(pointToPoint.Install(nodes.Get(0), nodes.Get(2)));
devices.Add(pointToPoint.Install(nodes.Get(1), nodes.Get(3)));
devices.Add(pointToPoint.Install(nodes.Get(2), nodes.Get(3)));
devices.Add(pointToPoint.Install(nodes.Get(2), nodes.Get(4)));
devices.Add(pointToPoint.Install(nodes.Get(2), nodes.Get(6)));
devices.Add(pointToPoint.Install(nodes.Get(4), nodes.Get(6)));
devices.Add(pointToPoint.Install(nodes.Get(5), nodes.Get(5)));

// the rest of your script