How to Begin Implement Network Path Latency in NS3

To implement and analyze the network path latency using NS3, we can estimate the total delay undergone by a packet to move from the source node to the destination node through certain path. At intermediate nodes, path latency contains propagation delay, transmission delay, processing delay, and queuing delay.

Steps to Implement Network Path Latency in NS3

1. Understand Path Latency

• Path Latency is the duration moving a path for a packet from the source to the destination node. It can be computed by:

Path Latency=Propagation Delay+Transmission Delay+Queuing Delay+Processing Delay\text{Path Latency} = \text{Propagation Delay} + \text{Transmission Delay} + \text{Queuing Delay} + \text{Processing Delay}Path Latency=Propagation Delay+Transmission Delay+Queuing Delay+Processing Delay

• Following is crucial modules:
  • Propagation Delay: It’s time to move along the medium for the signal.
  • Transmission Delay: Time for sending a packet to the medium.
  • Processing Delay: Time consumed to execute the packet at every node.
  • Queuing Delay: It can be consumed time within queues at each node.

2. Set Up NS3 Simulation

1. Install NS3:
   • Make sure that we have installed and configured NS3 on the computer. Also, we can download it.
2. Define Network Topology:
   • Make a network topology including numerous intermediate nodes for instance Source → Router(s) → Destination.

3. Log Timestamps at Source and Destination

1. Timestamp the Packet:
   • Integrate a timestamp at the source node once the packet is made.
2. Measure Latency at the Destination:
   • Determine the variance among the arrival time at the destination and the timestamp integrated at the source node.

4. Implement Path Latency Measurement

Here’s a sample script of NS3 to estimate the path latency.

Example Script: Network Path Latency in NS3

#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;

class PathLatencyTracker {

public:

void RecordTimestamp(Ptr<const Packet> packet) {

m_sendTime = Simulator::Now();

}

void CalculateLatency(Ptr<const Packet> packet) {

Time latency = Simulator::Now() – m_sendTime;

NS_LOG_UNCOND(Simulator::Now().GetSeconds() << “s: Path Latency = ” << latency.GetMilliSeconds() << ” ms”);

}

private:

Time m_sendTime;

};

PathLatencyTracker latencyTracker;

void SendPacket(Ptr<Socket> socket, Ipv4Address destinationAddress, uint16_t destinationPort) {

Ptr<Packet> packet = Create<Packet>(1024); // 1024-byte packet

socket->SendTo(packet, 0, InetSocketAddress(destinationAddress, destinationPort));

latencyTracker.RecordTimestamp(packet);

}

void ReceivePacket(Ptr<Socket> socket) {

Ptr<Packet> packet = socket->Recv();

latencyTracker.CalculateLatency(packet);

}

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

CommandLine cmd;

cmd.Parse(argc, argv);

// Create nodes

NodeContainer nodes;

nodes.Create(3); // Source, Intermediate Router, Destination

// Configure Point-to-Point links

PointToPointHelper pointToPoint;

pointToPoint.SetDeviceAttribute(“DataRate”, StringValue(“10Mbps”));

pointToPoint.SetChannelAttribute(“Delay”, StringValue(“5ms”));

NetDeviceContainer devices1 = pointToPoint.Install(nodes.Get(0), nodes.Get(1)); // Source to Router

NetDeviceContainer devices2 = pointToPoint.Install(nodes.Get(1), nodes.Get(2)); // Router to Destination

// Install Internet stack

InternetStackHelper stack;

stack.Install(nodes);

// Assign IP addresses

Ipv4AddressHelper address;

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

Ipv4InterfaceContainer interfaces1 = address.Assign(devices1);

address.SetBase(“10.1.2.0”, “255.255.255.0”);

Ipv4InterfaceContainer interfaces2 = address.Assign(devices2);

// Create sockets

Ptr<Socket> sender = Socket::CreateSocket(nodes.Get(0), TypeId::LookupByName(“ns3::UdpSocketFactory”));

Ptr<Socket> receiver = Socket::CreateSocket(nodes.Get(2), TypeId::LookupByName(“ns3::UdpSocketFactory”));

uint16_t destinationPort = 8080;

receiver->Bind(InetSocketAddress(Ipv4Address::GetAny(), destinationPort));

receiver->SetRecvCallback(MakeCallback(&ReceivePacket));

// Schedule packet sending

Simulator::Schedule(Seconds(1.0), &SendPacket, sender, interfaces2.GetAddress(1), destinationPort);

Simulator::Run();

Simulator::Destroy();

return 0;

}

Explanation of the Script

1. Network Topology:
   • Three nodes: Source, Intermediate Router, and Destination are three nodes of network topology.
2. Path Latency Measurement:
   • The PathLatencyTracker class monitors when a packet is transmitted and determines the latency once it is inherited on the destination end.
3. Packet Flow:
   • The packet moves from the source node to the router that sends it to the destination node.
   • The script records the latency are monitored among the source and destination.
4. Simulated Delays:
   • Every single link launches a broadcast delay of 5ms.

5. Run the Simulation

1. Execute the simulation script:

./waf –run “your-script-name”

1. Monitor the records for estimating the path latency values.

6. Analyze Results

• Accumulate latency data for numerous packets.
• Examine the performance parameters such as:
  • Latency Variations (Jitter)
  • Maximum and Minimum Path Latency
  • Average Path Latency

Advanced Extensions

1. Multiple Paths:
   • Replicate several paths and then equate its latencies.
   • Make use of dynamic routing protocols such as OSPF.
2. Dynamic Traffic:
   • Integrate the dynamic traffic models to leverage the applications like OnOffApplication.
3. Complex Topologies:
   • Make realistic network scenarios using additional routers and nodes.
4. Visualization:
   • Transfer latency data into external tools such as MATLAB or Excel used for graphical analysis.

We accomplished the detailed procedural approach to implement and analyze the Network Path Latency using NS3 environment. We are prepared to expand it with further information if needed.