How to Calculate Network Response Time in ns3

To calculate the response time in ns3, we need to compute the time taken for a request to send and receives from the client to server and server to the client. This encompasses the transmission delay, propagation delay and processing time at the server.

Here are the procedures to compute the response time in ns3:

1. Set up Your Simulation Environment: Make a network topology; configure nodes, links, and protocols.
2. Install Applications: Set up applications on the nodes to generate and receive traffic.
3. Trace the Packets: To record the send and receive times of request and response packets by use of ns3 tracing abilities.
4. Calculate Response Time: Subtract the send time of the request packet from the receive time of the response packet.

Example: Simple Network with UDP Echo

In the sample, we make a simple network topology with two nodes connected by a point-to-point link and compute the response time using UDP echo client and server.

Step 1: Set Up Your Simulation Environment

#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”

using namespace ns3;

NS_LOG_COMPONENT_DEFINE (“ResponseTimeExample”);

void PacketSent (Ptr<const Packet> packet)

{

NS_LOG_UNCOND (“Packet sent at time ” << Simulator::Now ().GetSeconds ());

}

void PacketReceived (Ptr<const Packet> packet)

{

NS_LOG_UNCOND (“Packet received at time ” << Simulator::Now ().GetSeconds ());

}

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

{

// Create two 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”));

// Install the link devices on the nodes

NetDeviceContainer devices;

devices = pointToPoint.Install (nodes);

// Install the internet stack

InternetStackHelper stack;

stack.Install (nodes);

// Assign IP addresses

Ipv4AddressHelper address;

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

Ipv4InterfaceContainer interfaces = address.Assign (devices);

// Set up the UDP echo server on Node 1

uint16_t port = 9; // well-known echo port number

UdpEchoServerHelper echoServer (port);

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

serverApps.Start (Seconds (1.0));

serverApps.Stop (Seconds (10.0));

// Set up the UDP echo client on Node 0

UdpEchoClientHelper echoClient (interfaces.GetAddress (1), port);

echoClient.SetAttribute (“MaxPackets”, UintegerValue (10));

echoClient.SetAttribute (“Interval”, TimeValue (Seconds (1.0))); // 1 packet per second

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

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

clientApps.Start (Seconds (2.0));

clientApps.Stop (Seconds (10.0));

// Enable tracing

devices.Get (0)->TraceConnectWithoutContext (“MacTx”, MakeCallback (&PacketSent));

devices.Get (1)->TraceConnectWithoutContext (“MacRx”, MakeCallback (&PacketReceived));

devices.Get (1)->TraceConnectWithoutContext (“MacTx”, MakeCallback (&PacketSent));

devices.Get (0)->TraceConnectWithoutContext (“MacRx”, MakeCallback (&PacketReceived));

// Run the simulation

Simulator::Run ();

Simulator::Destroy ();

return 0;

}

Step 2: Install Applications

In this sample, a UDP echo server is installed on Node 1 and a UDP echo client on Node 0. The client sends 10 packets, each 1024 bytes in size, at an interval of 1 second.

Step 3: Trace the Packets

Packet transmission and reception are traced using callbacks. The PacketSent and PacketReceived functions are used to log the event times.

Step 4: Calculate Response Time

After running the simulation, parse the log to extract the send and receive times of request and response packets, and calculate the response time.

Example Python Script to Calculate Response Time

Here, we provide the sample snippet to compute the response time in ns3:

import re

request_sent_times = []

response_received_times = []

# Regular expressions to match the log output

send_pattern = re.compile(r”Packet sent at time (\d+\.\d+)”)

receive_pattern = re.compile(r”Packet received at time (\d+\.\d+)”)

# Parse the log file

with open(“ns3-output.log”, “r”) as log_file:

for line in log_file:

send_match = send_pattern.search(line)

receive_match = receive_pattern.search(line)

if send_match:

request_sent_times.append(float(send_match.group(1)))

if receive_match:

response_received_times.append(float(receive_match.group(1)))

# Calculate Response Time

response_times = []

for request_time, response_time in zip(request_sent_times, response_received_times):

response_times.append(response_time – request_time)

average_response_time = sum(response_times) / len(response_times) if response_times else 0

print(f”Average Response Time: {average_response_time} seconds”)

Explanation

Here, we provide the description for the process of response time in ns3:

1. Set Up Your Simulation Environment: Create two nodes and connect them with a point-to-point link.
2. Install Applications: Install a UDP echo server on Node 1 and a UDP echo client on Node 0. Configure the client to send a specified number of packets at a specified interval.
3. Trace the Packets: Use callbacks to log the times when request packets are sent and response packets are received.
4. Calculate Response Time: Parse the log file to extract send and receive times, then calculate the response time by subtracting the send time of each request packet from the receive time of the corresponding response packet.

Overall, we learned how the Response Time will compute and evaluate in a particular interval in ns3 simulation tool. We also deliver additional details on how the response time calculates in other simulation tools.

Working diligently to obtain a comparison analysis for networking, we will assist you in determining the Response Time using ns3tool.