How to Calculate Network Latency in ns3

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Calculating network latency in ns3 involves the following steps.

Steps for calculating network latency

1. Set up the simulation :

• To simulate the network, create a network topology with nodes, protocols and links configured.

2. Install applications :

• On the nodes, setup applications to generate and receive traffic.

3. Trace the packets :

• To record sending and receiving times of packets, use ns3 tracing capabilities.

4. Calculate network latency :

• Subtract the send time from the receive time for each packet.

Example of a simple network latency calculation

Create a basic network topology with point-to-point link.

set up the 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”

using namespace ns3;

NS_LOG_COMPONENT_DEFINE (“NetworkLatencyExample”);

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 and client

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));

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

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));

// Enable tracing

AsciiTraceHelper ascii;

pointToPoint.EnableAsciiAll (ascii.CreateFileStream (“network-latency.tr”));

// Run the simulation

Simulator::Run ();

Simulator::Destroy ();

return 0;

}

2. Install applications

In the above example, on one node a UDP echo server is installed. and on another node, a UDP echo client is installed.

3. Trace the packets

There are several ways to trace packets in ns3. We can use either ASCII or PCAP tracing. But in our example, we enabled ASCII tracing.

4. calculate latency

Parse the trace file to extract the send and receive times of packets, After running the simulation. Here is a basic way to process the trace file:

grep “Send” network-latency.tr > send-times.txt

grep “Received” network-latency.tr > recv-times.txt

We can then calculate the latency by utilizing a script or manually by subtracting the send times from the receive times.

Example Python Script to Calculate Latency

below is an example Python script to calculate the latency:

send_times = []

recv_times = []

with open(“send-times.txt”, “r”) as send_file:

for line in send_file:

time = float(line.split()[1])  # Assuming the time is the second field

send_times.append(time)

with open(“recv-times.txt”, “r”) as recv_file:

for line in recv_file:

time = float(line.split()[1])  # Assuming the time is the second field

recv_times.append(time)

latencies = []

for send_time, recv_time in zip(send_times, recv_times):

latencies.append(recv_time – send_time)

average_latency = sum(latencies) / len(latencies)

print(f”Average Latency: {average_latency} seconds”)

Explanation

1. Simulation setup :

Two nodes are created. Those nodes are connected using a point-to-point link.

2. Application setup :

On one node, a UDP echo server is installed. and On another node, a UDP echo client is installed.

3. Packet tracing :

To record packet events, enable ASCII.

4. Calculate latency :

Calculate the latency by extract sending and receiving times from the trace file.

On the whole, we had an analysis on calculating network latency in ns3 by following several steps. We provide an overview on Network latency projects .