How to Calculate Stalling in ns3

To calculate the stalling in ns3, we need to track and detecting periods of streaming playback buffer, when the buffer process empty that make happen playback to pause or “stall”.

Here are the procedures on how to configure and compute the stalling events:

Steps to Calculate Stalling

  1. Set up the Simulation: generate network topology, setup the nodes and download the essential applications.
  2. Implement Buffer Management: Mimic a playback buffer that obtains data and reduces as it “plays” the media.
  3. Monitor Buffer Levels: Track the buffer occupancy over time and identify when it runs empty.
  4. Calculate Stalling Events: Count the number of times the buffer runs empty and measure the duration of these stalling periods.

Example Implementation

Here, we provide the sample configuration to build a fundamental network simulation in ns3 and computes the stalling events:

Setting Up the Network Simulation

#include “ns3/core-module.h”

#include “ns3/network-module.h”

#include “ns3/internet-module.h”

#include “ns3/point-to-point-module.h”

#include “ns3/applications-module.h”

#include <iostream>

#include <fstream>

using namespace ns3;

NS_LOG_COMPONENT_DEFINE(“StallingExample”);

// Global variables to simulate the playback buffer

double bufferOccupancy = 0.0; // in seconds of media

double playbackRate = 1.0; // rate at which media is played, in seconds per second

double bufferThreshold = 2.0; // minimum buffer occupancy before stalling occurs

double bufferSize = 10.0; // maximum buffer size in seconds of media

double lastBufferUpdateTime = 0.0;

bool isStalling = false;

double totalStallingTime = 0.0;

int stallingEvents = 0;

void BufferUpdate(double dataRate, double currentTime) {

// Update buffer occupancy based on data received since last update

double timeElapsed = currentTime – lastBufferUpdateTime;

double dataReceived = dataRate * timeElapsed; // data received in seconds of media

bufferOccupancy += dataReceived;

// Simulate media playback

bufferOccupancy -= timeElapsed * playbackRate;

// Check for stalling

if (bufferOccupancy < 0) {

bufferOccupancy = 0;

if (!isStalling) {

isStalling = true;

stallingEvents++;

}

} else if (bufferOccupancy > bufferThreshold && isStalling) {

totalStallingTime += currentTime – lastBufferUpdateTime;

isStalling = false;

}

// Clamp buffer occupancy to its maximum size

if (bufferOccupancy > bufferSize) {

bufferOccupancy = bufferSize;

}

lastBufferUpdateTime = currentTime;

}

int main(int argc, char *argv[]) {

// Set up the default simulation parameters

Time::SetResolution(Time::NS);

LogComponentEnable(“StallingExample”, LOG_LEVEL_INFO);

// Create nodes

NodeContainer nodes;

nodes.Create(2);

// Set up the point-to-point link

PointToPointHelper pointToPoint;

pointToPoint.SetDeviceAttribute(“DataRate”, StringValue(“5Mbps”));

pointToPoint.SetChannelAttribute(“Delay”, StringValue(“2ms”));

NetDeviceContainer devices;

devices = pointToPoint.Install(nodes);

// Install the Internet stack

InternetStackHelper stack;

stack.Install(nodes);

Ipv4AddressHelper address;

address.SetBase(“10.1.1.0”, “255.255.255.0”);

Ipv4InterfaceContainer interfaces = address.Assign(devices);

// Set up a UDP server

uint16_t port = 9;

UdpServerHelper server(port);

ApplicationContainer serverApps = server.Install(nodes.Get(1));

serverApps.Start(Seconds(1.0));

serverApps.Stop(Seconds(20.0));

// Set up a UDP client

uint32_t packetSize = 1024; // 1 KB

uint32_t maxPacketCount = 3200; // 3200 KB total data

Time interPacketInterval = Seconds(0.01); // 10 ms interval

UdpClientHelper client(interfaces.GetAddress(1), port);

client.SetAttribute(“MaxPackets”, UintegerValue(maxPacketCount));

client.SetAttribute(“Interval”, TimeValue(interPacketInterval));

client.SetAttribute(“PacketSize”, UintegerValue(packetSize));

ApplicationContainer clientApps = client.Install(nodes.Get(0));

clientApps.Start(Seconds(2.0));

clientApps.Stop(Seconds(20.0));

// Monitor buffer occupancy every 0.1 seconds

Simulator::Schedule(Seconds(0.1), &BufferUpdate, 0.8, 0.1); // Example data rate: 0.8 seconds of media per second

Simulator::Stop(Seconds(20.0));

Simulator::Run();

// Final buffer update

BufferUpdate(0.8, Simulator::Now().GetSeconds());

if (isStalling) {

totalStallingTime += Simulator::Now().GetSeconds() – lastBufferUpdateTime;

}

std::cout << “Total Stalling Events: ” << stallingEvents << std::endl;

std::cout << “Total Stalling Time: ” << totalStallingTime << ” seconds” << std::endl;

Simulator::Destroy();

return 0;

}

Explanation:

The given below is the process for stalling events:

  1. Simulation Setup:
    • Create two nodes and connect them using a point-to-point link.
    • Install the Internet stack on both nodes and assign IP addresses.
  2. Application Setup:
    • Install a UDP server on the destination node (Node 1).
    • Install a UDP client on the source node (Node 0) to send packets to the server.
  3. Buffer Management:
    • Simulate a playback buffer by updating its occupancy based on the data rate and playback rate.
    • Monitor the buffer occupancy and detect stalling events when the buffer runs empty.
  4. Stalling Calculation:
    • Count the number of stalling events and measure the total stalling time.
  5. Simulation Execution:
    • Run the simulation for a specified period and monitor the buffer occupancy at regular intervals.

Overall, we had learned how the stalling event calculated and executed in ns3 tool. We also provide further information about how the stalling event performs in other simulator.

Connect with ns3simulation.com to receive your networking comparative analysis from our developers, and we will assist you in determining stalling in ns3tool. We provide assistance for all kinds of ns3simulation projects that use ns3tool to calculate stalling.