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# How to Calculate Network Queue time in Ns3

To calculate network queue time in ns3, we need to add trace sources to the queue. Because for calculating the network queue we have to measure the time packets spend in the queue before transmitting the packets through network and capture the enqueue and dequeue events. The steps given below helps us to calculate network queue time.

Step-by-step to Calculate Network Queue Time

1. Set Up the ns3 Environment:
• Make sure ns3 is installed.
2. Define the Network Topology:
• Create a network topology with nodes and links.
3. Configure Queue Tracing:
• Use NS3’s tracing capabilities to capture enqueue and dequeue events.
4. Calculate Queue Time:
• Measure the time difference between enqueue and dequeue events for each packet.

Example Code

Here an example given how to set up a simple ns3 simulation to calculate the queue time for packets in a point-to-point network.

#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 “ns3/queue.h”

using namespace ns3;

NS_LOG_COMPONENT_DEFINE (“QueueTimeExample”);

std::map<uint64_t, Time> enqueueTimes;

void EnqueueTrace(Ptr<const Packet> packet)

{

enqueueTimes[packet->GetUid()] = Simulator::Now();

}

void DequeueTrace(Ptr<const Packet> packet)

{

Time enqueueTime = enqueueTimes[packet->GetUid()];

Time dequeueTime = Simulator::Now();

Time queueTime = dequeueTime – enqueueTime;

NS_LOG_UNCOND (“Packet ” << packet->GetUid() << ” queue time: ” << queueTime.GetSeconds() << ” seconds”);

}

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

{

CommandLine cmd;

cmd.Parse (argc, argv);

Time::SetResolution (Time::NS);

NodeContainer nodes;

nodes.Create (2);

PointToPointHelper pointToPoint;

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

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

pointToPoint.SetQueue (“ns3::DropTailQueue”, “MaxPackets”, UintegerValue (100));

NetDeviceContainer devices;

devices = pointToPoint.Install (nodes);

InternetStackHelper stack;

stack.Install (nodes);

// Create a UDP server on node 1

UdpServerHelper server (9);

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

serverApp.Start (Seconds (1.0));

serverApp.Stop (Seconds (10.0));

// Create a UDP client on node 0

client.SetAttribute (“MaxPackets”, UintegerValue (320));

client.SetAttribute (“Interval”, TimeValue (MilliSeconds (10)));

client.SetAttribute (“PacketSize”, UintegerValue (1024));

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

clientApp.Start (Seconds (2.0));

clientApp.Stop (Seconds (10.0));

// Trace Enqueue and Dequeue events

Ptr<PointToPointNetDevice> dev = DynamicCast<PointToPointNetDevice> (devices.Get (0));

Ptr<Queue> queue = dev->GetQueue ();

queue->TraceConnectWithoutContext (“Enqueue”, MakeCallback (&EnqueueTrace));

queue->TraceConnectWithoutContext (“Dequeue”, MakeCallback (&DequeueTrace));

Simulator::Stop (Seconds (11.0));

Simulator::Run ();

Simulator::Destroy ();

return 0;

}

Explanation

1. Setup: The code sets up a simple point-to-point network between two nodes with a 5 Mbps link.
2. Applications: A UDP server is installed on node 1, and a UDP client is installed on node 0 to generate traffic.
3. Queue Tracing: The EnqueueTrace and DequeueTrace functions are connected to the enqueue and dequeue events of the queue. These functions log the time a packet is enqueued and dequeued, and calculate the queue time.
4. Queue Time Calculation: The queue time for each packet is calculated as the difference between the dequeue time and the enqueue time.

Running the Simulation

Compile and run the simulation using the following commands in the ns3 environment:

./waf configure

./waf build

./waf –run your-script-name

Replace script-name with the actual name of the script file.

From the above example we all get to know that measuring the time packets spend in queue before transmitting we can calculate the network queue time in ns3.

To accurately determine the Network Queue Time within your project’s Ns3, kindly provide us with the relevant parameters. We will ensure to deliver the most precise results. For the measurement of time packets related to your projects, please share the necessary details with us. We are committed to delivering optimal outcomes for your requirements.