NS3: Dynamically Change the bandwidth



Based on https://blog.csdn.net/u010643777/article/details/80590045, I wrote this lab



N0(TCP Sender)----P2Plink(5Mbps,2ms)---N1(TCP Sink)


At 5th second, I will change the bandwidth of P2Plink from 5Mbps to 1000000bps.


test-change-bandwidth.cc (put this file under scratch)

#include <fstream>

#include <string.h>


#include "ns3/core-module.h"

#include "ns3/internet-module.h"

#include "ns3/point-to-point-module.h"

#include "ns3/packet-sink.h"

#include "ns3/packet-sink-helper.h"

#include "ns3/applications-module.h"


using namespace ns3;




Ptr<PacketSink> sink;                         /* Pointer to the packet sink application */

uint64_t lastTotalRx = 0;                     /* The value of the last total received bytes */



CalculateThroughput ()


  Time now = Simulator::Now ();                                         /* Return the simulator's virtual time. */

  double cur = (sink->GetTotalRx () - lastTotalRx) * (double) 8 / 1e6;     /* Convert Application RX Packets to MBits. */

  std::cout << now.GetSeconds () << "\t" << cur << std::endl;

  lastTotalRx = sink->GetTotalRx ();

  Simulator::Schedule (MilliSeconds (1000), &CalculateThroughput);




ChangeBandwith(Ptr<NetDevice> netdevice, uint64_t bps)


  PointToPointNetDevice *device=static_cast<PointToPointNetDevice *>(PeekPointer(netdevice));





main (int argc, char *argv[])


  NS_LOG_INFO ("Create nodes.");

  NodeContainer n;

  n.Create (2);


  InternetStackHelper internet;

  internet.Install (n);


  NS_LOG_INFO ("Create channels.");


  PointToPointHelper pointToPoint;

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

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

  pointToPoint.SetDeviceAttribute("Mtu", UintegerValue(1400));  

  NetDeviceContainer p2pDevices;

  p2pDevices = pointToPoint.Install (n);    


  Ipv4AddressHelper ipv4;


  NS_LOG_INFO ("Assign IP Addresses.");

  ipv4.SetBase ("", "");

  Ipv4InterfaceContainer i = ipv4.Assign (p2pDevices);


  NS_LOG_INFO ("Create Applications.");


  PacketSinkHelper sinkHelper ("ns3::TcpSocketFactory", InetSocketAddress (Ipv4Address::GetAny (), 9));

  ApplicationContainer sinkApp = sinkHelper.Install (n.Get(1));

  sink = StaticCast<PacketSink> (sinkApp.Get (0));


  BulkSendHelper source ("ns3::TcpSocketFactory", (InetSocketAddress (i.GetAddress (1), 9)));

  source.SetAttribute ("MaxBytes", UintegerValue (0));

  ApplicationContainer sourceApps = source.Install (n.Get (0));


  sourceApps.Start (Seconds (1.0));

  sourceApps.Stop (Seconds (15.0));

  sinkApp.Start (Seconds (0.0));

  Simulator::Schedule (Seconds (1.0), &CalculateThroughput);


  //At 5th second, change the bandwidth from 5Mbps to 1000000bps

  Simulator::Schedule (Seconds (5.0), &ChangeBandwith, p2pDevices.Get(0), 1000000);


  Simulator::Stop (Seconds (16.0));

  NS_LOG_INFO ("Run Simulation.");

  Simulator::Run ();

  Simulator::Destroy ();

  NS_LOG_INFO ("Done.");





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Last Modified: 2022/2/14


Dr. Chih-Heng Ke

Department of Computer Science and Information Engineering, National Quemoy University, Kinmen, Taiwan

Email: smallko@gmail.com