How to Implement Congestion Control in ns3

To implement the congestion control in ns3, with the help different techniques like TCP congestion control algorithms, queue management and traffic shaping, we can be able to control and monitor the congestion simply by creating network simulation.

Here, we provide the step-by-step implementation to walk you through this:

Step-by-Step Implementation:

Step 1: Setup ns3 Environment

Make sure you have installed the ns3 on your computer.

Step 2: Include Necessary Modules

We have to include the below ns3 modules in the script:

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#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/traffic-control-module.h”

#include “ns3/flow-monitor-module.h”

Step 3: Create the Simulation Script

1. Setup Nodes and Network:

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using namespace ns3;

NS_LOG_COMPONENT_DEFINE (“CongestionControlExample”);

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

{

CommandLine cmd;

cmd.Parse (argc, argv);

// Create nodes

NodeContainer nodes;

nodes.Create (4);

// Create point-to-point links

PointToPointHelper pointToPoint;

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

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

NetDeviceContainer devices;

devices = pointToPoint.Install (nodes.Get (0), nodes.Get (1));

devices = pointToPoint.Install (nodes.Get (1), nodes.Get (2));

devices = pointToPoint.Install (nodes.Get (2), nodes.Get (3));

// Install 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);

// Traffic Control: Set up queue disciplines

TrafficControlHelper tch;

tch.SetRootQueueDisc (“ns3::RedQueueDisc”);

tch.Install (devices);

// Set up applications

uint16_t port = 9;  // Discard port (RFC 863)

// Server application on node 3

Address serverAddress (InetSocketAddress (Ipv4Address::GetAny (), port));

PacketSinkHelper packetSinkHelper (“ns3::UdpSocketFactory”, serverAddress);

ApplicationContainer sinkApps = packetSinkHelper.Install (nodes.Get (3));

sinkApps.Start (Seconds (1.0));

sinkApps.Stop (Seconds (20.0));

// Client application on node 0

OnOffHelper onoff (“ns3::UdpSocketFactory”, Address (InetSocketAddress (interfaces.GetAddress (3), port)));

onoff.SetConstantRate (DataRate (“1Mbps”));

ApplicationContainer apps = onoff.Install (nodes.Get (0));

apps.Start (Seconds (2.0));

apps.Stop (Seconds (20.0));

// Flow monitor

FlowMonitorHelper flowmon;

Ptr<FlowMonitor> monitor = flowmon.InstallAll ();

Simulator::Stop (Seconds (20.0));

Simulator::Run ();

monitor->SerializeToXmlFile(“flowmon-results.xml”, true, true);

Simulator::Destroy ();

return 0;

}

Step 4: Run the Simulation

Now we have to compile and run your simulation script:

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./waf configure

./waf build

./waf –run CongestionControlExample

Explanation

• Node Creation: Create nodes representing different devices in the network.
• Point-to-Point Links: Configure point-to-point links between nodes.
• Internet Stack: In all nodes, we have to install the Internet stack.
• IP Configuration: We have to allocate IP addresses to the nodes.
• Traffic Control: We have to install a queue discipline (like RED) using the TrafficControlHelper. In the above sample, to manage the queue lengths and drop the packets probabilistically we used the RED (Random Early Detection).
• Applications: To simulate the traffic amongst the nodes we can use OnOffApplication and PacketSink.
• Flow Monitor: To aggregate and save the traffic date as an XML file for further analysis we can use the flow.

Advanced Congestion Control Techniques

1. TCP Congestion Control Algorithms:

We can implement various TCP congestion control algorithms like TCP NewReno, TCP Cubic, or TCP BBR.

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Config::SetDefault (“ns3::TcpL4Protocol::SocketType”, TypeIdValue (TcpNewReno::GetTypeId ()));

You can replace TcpNewReno with TcpCubic, TcpBbr, etc.

1. Queue Management:

We can execute the various queue management techniques such as CoDel, FQ-CoDel, or PIE.

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TrafficControlHelper tch;

tch.SetRootQueueDisc (“ns3::FqCoDelQueueDisc”);

tch.Install (devices);

1. Traffic Shaping:

We can  control the rate and burst size of traffic flows with the help of traffic shaping.

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TrafficControlHelper tch;

tch.SetRootQueueDisc (“ns3::TbfQueueDisc”, “MaxSize”, StringValue (“100p”), “Burst”, StringValue (“100p”));

tch.Install (devices);

1. Rate Limiting:

With the help of token bucket filters (TBF) or hierarchical token bucket (HTB) queues, we can execute rate limiting.

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TrafficControlHelper tch;

tch.SetRootQueueDisc (“ns3::TbfQueueDisc”, “MaxSize”, StringValue (“100p”), “Burst”, StringValue (“100p”), “Rate”, DataRateValue (DataRate (“1Mbps”)));

tch.Install (devices);

1. Monitoring and Analysis:

We can analyze the performance and efficiency of the congestion control mechanisms using flow monitor.

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// Flow monitor

FlowMonitorHelper flowmon;

Ptr<FlowMonitor> monitor = flowmon.InstallAll ();

Simulator::Stop (Seconds (20.0));

Simulator::Run ();

monitor->SerializeToXmlFile(“flowmon-results.xml”, true, true);

Simulator::Destroy ();

Finally, as we discussed earlier we are completely seen and offer the step-by-step implementation on congestion control in ns3 tool. If you need any additional datas regarding this topic, we will help with that. We share with you best project ideas on congestion control in ns3 tool.