How to Calculate Network Buffering in ns3

To calculate the network buffering in ns3, that need to track the features of packet queues in the network devices. In particular, we need to measure how packets are buffered, the delays they experience, and how often packets are dropped due to buffer overflow. Here are the detailed procedures on how to achieve this in ns3:

Steps to Calculate Network Buffering

1. Set Up the ns3 Environment:
   • Make sure ns3 is installed in the computer.
2. Define the Network Topology:
   • Create a network topology with nodes and links.
3. Configure Queues:
   • Configure the queues in the network devices.
4. Install Applications:
   • Install traffic-generating applications on the nodes to simulate network traffic.
5. Monitor Queue Metrics:
   • Use trace sources or callbacks to monitor queue metrics such as queue size, packet enqueue/dequeue events, and packet drops.
6. Analyse Buffering Behaviour:
   • Calculate metrics such as average queue length, maximum queue length, packet waiting time in the queue, and packet drop rate.

Example Code

Here is a sample on how to setup a basic ns3 simulation to estimate the buffering metrics in a p2p 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 (“NetworkBufferingExample”);

uint32_t totalEnqueuedPackets = 0;

uint32_t totalDequeuedPackets = 0;

uint32_t totalDroppedPackets = 0;

Time totalQueueingDelay;

void EnqueueTrace (Ptr<const Packet> packet)

{

totalEnqueuedPackets++;

}

void DequeueTrace (Ptr<const Packet> packet)

{

totalDequeuedPackets++;

}

void DropTrace (Ptr<const Packet> packet)

{

totalDroppedPackets++;

}

void QueueDelayTrace (Time oldValue, Time newValue)

{

totalQueueingDelay += newValue;

}

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 (10));

NetDeviceContainer devices;

devices = pointToPoint.Install (nodes);

InternetStackHelper stack;

stack.Install (nodes);

Ipv4AddressHelper address;

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

address.Assign (devices);

// 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

UdpClientHelper client (Ipv4Address (“10.1.1.1”), 9);

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, Dequeue, and Drop events

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

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

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

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

queue->TraceConnectWithoutContext (“Drop”, MakeCallback (&DropTrace));

queue->TraceConnectWithoutContext (“QueueingDelay”, MakeCallback (&QueueDelayTrace));

Simulator::Stop (Seconds (11.0));

Simulator::Run ();

double averageQueueingDelay = totalQueueingDelay.GetSeconds () / totalDequeuedPackets;

NS_LOG_UNCOND (“Total Enqueued Packets: ” << totalEnqueuedPackets);

NS_LOG_UNCOND (“Total Dequeued Packets: ” << totalDequeuedPackets);

NS_LOG_UNCOND (“Total Dropped Packets: ” << totalDroppedPackets);

NS_LOG_UNCOND (“Average Queueing Delay: ” << averageQueueingDelay << ” seconds”);

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 and a 2 ms delay.
2. Queue Configuration: A DropTailQueue with a maximum of 10 packets is configured on the point-to-point links.
3. Applications: A UDP server is installed on node 1, and a UDP client is installed on node 0 to generate traffic.
4. Queue Tracing: The EnqueueTrace, DequeueTrace, DropTrace, and QueueDelayTrace functions are connected to the corresponding events in the queue to monitor the buffering behavior.
5. Buffering Metrics Calculation: The total number of enqueued, dequeued, and dropped packets are tracked, along with the total queueing delay. After the simulation, the average queueing delay is calculated and printed.

Running the Simulation

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

./waf configure

./waf build

./waf –run your-script-name

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

In this script, we understand how the network buffering estimated and simulation in the ns3 implementation. We give the additional details regarding to network buffering in ns3 scenario. Let’s analyze your network buffering using ns3tool and continue with performance evaluation. Feel free to provide us with your parameters at ns3simulation.com for optimal results from our team.