How to Simulate SDN Projects Using NS3

To simulate Software-Defined Networking (SDN) projects using NS3 has usually includes isolating the control plane (handled by an SDN controller) from the data plane (handled by switches or routers). SDN enables the dynamic management of network traffic across programmable controllers that centrally handle the features of the network’s infrastructure.

There are numerous ways to replicate SDN in NS3 that contain using external SDN controllers such as OpenFlow controllers or incorporated SDN simulation libraries. NS3 deliver an OpenFlow module that can be incorporated with real or simulated SDN controllers such as POX, RYU, or ONOS.

Here’s a step-by-step guide to simulate SDN projects in NS3 using OpenFlow.

Steps to Simulate the Software-Defined Networking Projects Using NS3

  1. Install NS3 with OpenFlow Support

Ensure NS3 is installed with OpenFlow support. We can validate this by testing if the OpenFlow module is available:

./waf list-modules

Look for openflow in the list of modules.

If not available, we need to reconfigure NS3 to permits the OpenFlow module. Some versions of NS3 can needs additional dependencies such as OpenFlow library.

  1. Basic Structure of an SDN Network
  • SDN Controller: To handle the network centrally by regulating the flow rules on switches.
  • OpenFlow Switches: Forward traffic according to rules pushed by the controller.
  • Hosts: End devices that send and receive traffic.
  1. Example SDN Simulation Using NS3 and OpenFlow

The following sample shows on how to simulate an SDN network with two hosts and two OpenFlow-enabled switches. A simple SDN controller is used to handle traffic flow among the switches.

Example Code for SDN Simulation:

#include “ns3/core-module.h”

#include “ns3/internet-module.h”

#include “ns3/point-to-point-module.h”

#include “ns3/applications-module.h”

#include “ns3/openflow-module.h”

using namespace ns3;

NS_LOG_COMPONENT_DEFINE (“SimpleSDNExample”);

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

{

CommandLine cmd;

cmd.Parse (argc, argv);

// Create nodes for the controller, switches, and hosts

NodeContainer controllerNode;

controllerNode.Create (1);  // SDN controller

NodeContainer switchNodes;

switchNodes.Create (2);  // Two OpenFlow switches

NodeContainer hostNodes;

hostNodes.Create (2);  // Two hosts

// Install Internet stack on the hosts

InternetStackHelper internet;

internet.Install (hostNodes);

// Create point-to-point links between hosts and switches

PointToPointHelper pointToPoint;

pointToPoint.SetDeviceAttribute (“DataRate”, StringValue (“100Mbps”));

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

// Connect host 1 to switch 1, host 2 to switch 2

NetDeviceContainer hostSwitch1Devices = pointToPoint.Install (hostNodes.Get (0), switchNodes.Get (0));

NetDeviceContainer hostSwitch2Devices = pointToPoint.Install (hostNodes.Get (1), switchNodes.Get (1));

// Connect the two switches

NetDeviceContainer switchSwitchDevices = pointToPoint.Install (switchNodes.Get (0), switchNodes.Get (1));

// Assign IP addresses to hosts

Ipv4AddressHelper ipv4;

ipv4.SetBase (“10.1.1.0”, “255.255.255.0”);

Ipv4InterfaceContainer host1Interface = ipv4.Assign (hostSwitch1Devices);

ipv4.SetBase (“10.1.2.0”, “255.255.255.0”);

Ipv4InterfaceContainer host2Interface = ipv4.Assign (hostSwitch2Devices);

// Create and install OpenFlow switches

OpenFlowSwitchHelper ofSwitchHelper;

Ptr<Node> controller = controllerNode.Get (0);

Ptr<ns3::ofi::LearningController> learningController = CreateObject<ns3::ofi::LearningController> ();

ofSwitchHelper.Install (switchNodes.Get (0), switchSwitchDevices.Get (0), learningController);

ofSwitchHelper.Install (switchNodes.Get (1), switchSwitchDevices.Get (1), learningController);

// Install applications: Ping from host 1 to host 2

Ipv4Address serverAddress = host2Interface.GetAddress (0);

UdpEchoServerHelper echoServer (9);

ApplicationContainer serverApp = echoServer.Install (hostNodes.Get (1));

serverApp.Start (Seconds (1.0));

serverApp.Stop (Seconds (10.0));

UdpEchoClientHelper echoClient (serverAddress, 9);

echoClient.SetAttribute (“MaxPackets”, UintegerValue (1));

echoClient.SetAttribute (“Interval”, TimeValue (Seconds (1.0)));

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

ApplicationContainer clientApp = echoClient.Install (hostNodes.Get (0));

clientApp.Start (Seconds (2.0));

clientApp.Stop (Seconds (10.0));

// Enable PCAP tracing for packet capture

pointToPoint.EnablePcapAll (“sdn-openflow”);

// Run the simulation

Simulator::Run ();

Simulator::Destroy ();

return 0;

}

Explanation of Code:

  1. Controller, Switch, and Host Setup: Three types of nodes are generated—an SDN controller, OpenFlow switches, and hosts.
  2. Point-to-Point Links: Point-to-point links are generated among the hosts and switches, along with the switches.
  3. OpenFlow Switches: The OpenFlowSwitchHelper installs OpenFlow-enabled switches, and a simple learning controller is utilized to manage traffic. We can replace this with a custom controller or an external controller.
  4. IP Addresses: IP addresses are allocated to the hosts to facilitate communication.
  5. Applications: A UDP echo client-server is used to simulate interaction among Host 1 and Host 2.
  6. Packet Capture: PCAP monitoring is enabled to capture traffic for analysis.
  1. External SDN Controllers (e.g., POX or RYU)

If we want to incorporate NS3 with a real SDN controller such as POX, RYU, or ONOS, we need to permit an external communication among NS3’s OpenFlow switches and the external controller.

Steps for Integration:

  1. Install POX or RYU: Install the desired SDN controller on system. For instance, to install POX:

git clone https://github.com/noxrepo/pox.git

cd pox

./pox.py forwarding.l2_learning

  1. Configure OpenFlow Switches in NS3: Adjust the code to point the NS3 OpenFlow switches to the external controller’s IP and port.

Ptr<ns3::ofi::ExternalController> externalController = CreateObject<ns3::ofi::ExternalController> ();

externalController->SetAttribute (“RemoteAddress”, Ipv4AddressValue (“127.0.0.1”));  // Controller’s IP

externalController->SetAttribute (“RemotePort”, UintegerValue (6633));  // Default OpenFlow port

ofSwitchHelper.Install (switchNodes.Get (0), switchSwitchDevices.Get (0), externalController);

ofSwitchHelper.Install (switchNodes.Get (1), switchSwitchDevices.Get (1), externalController);

  1. Run the Controller and Simulation:
    • Initiate the POX/RYU controller.
    • Execute the NS3 simulation, and the switches will communicate with the external controller for flow rule management.
  1. Simulating Different SDN Topologies

We can expand the simple simulation to discover more complex SDN topologies such as data center networks, multi-controller SDNs, or SDN-WAN.

Example of a Data Center Topology:

We can replicate a Fat Tree topology with multiple switches and hosts associated in layers (core, aggregation, and edge switches). This is usually used in data center SDN simulations.

// Create core, aggregation, and edge switches

NodeContainer coreSwitches, aggSwitches, edgeSwitches;

coreSwitches.Create (2);

aggSwitches.Create (2);

edgeSwitches.Create (2);

// Create hosts connected to edge switches

NodeContainer hosts;

hosts.Create (4);

// Connect hosts to edge switches, edge to aggregation, aggregation to core switches

  1. Key Metrics for SDN Simulations
  • Flow Setup Time: The time taken for an SDN controller to configure flow rules on switches.
  • Packet Delivery Ratio (PDR): The ratio of successfully delivered packets to total sent packets.
  • Throughput: The data transfer rate among hosts.
  • Latency: The time it takes for a packet to travel from the source to the destination, that contain controller decision-making delays.
  • Controller Overhead: The load on the controller based on the number of flow requests it handles.
  1. Advanced SDN Features to Simulate
  • Dynamic Flow Management: Replicate dynamic flow rule updates according to changing network conditions.
  • Load Balancing: Execute load balancing using the SDN controller to share traffic via multiple paths.
  • QoS in SDN: Apply Quality of Service (QoS) policies in which the controller dynamically modifies flow priorities.
  • Security in SDN: Establish security behaviours such as intrusion detection, DDoS attack mitigation, and access control using SDN rules.
  1. Run the Simulation

Compile and execute the simulation using the following command:

./waf –run scratch/sdn-simulation

In the conclusion, we clearly simulate the Software-Defined Networking in the network that was executed in the ns3 tool that enhances the network performance. We plan to deliver additional information regarding the Software-Defined Networking.

For those looking to explore Software-Defined Networking (SDN) projects using the NS3 tool, phdprime.com is your go-to resource. We offer a comprehensive range of tools and resources designed to help you discover the best research ideas and topics that suit your specific requirements. Our expertise includes working with both real and simulated SDN controllers like POX, RYU, and ONOS

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