Steps to implement SD WAN protocol in ns3

To implement an SD-WAN (Software-Defined Wide Area Network) protocol in ns-3, we have to create a simulation that has a similar behavior of an SD-WAN network. SD-WAN incorporates features such as dynamic path selection, centralized control, and the ability to manage multiple WAN links. ns-3 doesn’t provide built-in support for SD-WAN.

Hence, we need to simulate its basic functionalities by combining existing modules and custom scripts.

Steps to implement SD-WAN protocol in ns3

Set up your environment

Make sure that ns3 is installed in the computer. If not, install it from the official ns3 website.

Create a new ns3 script

On your ns3 installation, create a new simulation script in the scratch directory.

Implement the SD-WAN network

Below is the example script for setting up a SD-WAN 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/ipv4-global-routing-helper.h”

using namespace ns3;

NS_LOG_COMPONENT_DEFINE (“SDWANSimulation”);

void

ChangePath (Ptr<Node> srcNode, Ptr<Node> dstNode, Ipv4Address newNextHop)

{

Ptr<Ipv4> ipv4 = srcNode->GetObject<Ipv4> ();

Ptr<Ipv4StaticRouting> staticRouting = Ipv4RoutingHelper::GetStaticRouting (ipv4);

staticRouting->RemoveRoute (1);

staticRouting->AddHostRouteTo (dstNode->GetObject<Ipv4> ()->GetAddress (1, 0).GetLocal (), newNextHop, 1);

NS_LOG_INFO (“Path changed to ” << newNextHop);

}

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

{

CommandLine cmd;

cmd.Parse (argc, argv);

// Create nodes

NodeContainer branchNodes;

branchNodes.Create (2);

NodeContainer wanNodes;

wanNodes.Create (2);

NodeContainer centralNode;

centralNode.Create (1);

// Set up point-to-point links

PointToPointHelper pointToPoint;

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

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

NetDeviceContainer devices;

// Branch to WAN links

devices = pointToPoint.Install (branchNodes.Get (0), wanNodes.Get (0));

devices = pointToPoint.Install (branchNodes.Get (1), wanNodes.Get (1));

// WAN to Central links

devices = pointToPoint.Install (wanNodes.Get (0), centralNode.Get (0));

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

// Install the internet stack on nodes

InternetStackHelper stack;

stack.Install (branchNodes);

stack.Install (wanNodes);

stack.Install (centralNode);

// Assign IP addresses to the devices

Ipv4AddressHelper address;

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

Ipv4InterfaceContainer if0 = address.Assign (devices.Get (0));

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

Ipv4InterfaceContainer if1 = address.Assign (devices.Get (1));

address.SetBase (“10.1.3.0”, “255.255.255.0”);

Ipv4InterfaceContainer if2 = address.Assign (devices.Get (2));

address.SetBase (“10.1.4.0”, “255.255.255.0”);

Ipv4InterfaceContainer if3 = address.Assign (devices.Get (3));

// Set up static routing

Ipv4StaticRoutingHelper staticRoutingHelper;

Ptr<Ipv4> ipv4Branch0 = branchNodes.Get (0)->GetObject<Ipv4> ();

Ptr<Ipv4StaticRouting> staticRoutingBranch0 = staticRoutingHelper.GetStaticRouting (ipv4Branch0);

staticRoutingBranch0->AddHostRouteTo (Ipv4Address (“10.1.3.2”), Ipv4Address (“10.1.1.2”), 1);

Ptr<Ipv4> ipv4Branch1 = branchNodes.Get (1)->GetObject<Ipv4> ();

Ptr<Ipv4StaticRouting> staticRoutingBranch1 = staticRoutingHelper.GetStaticRouting (ipv4Branch1);

staticRoutingBranch1->AddHostRouteTo (Ipv4Address (“10.1.4.2”), Ipv4Address (“10.1.2.2”), 1);

Ptr<Ipv4> ipv4Central = centralNode.Get (0)->GetObject<Ipv4> ();

Ptr<Ipv4StaticRouting> staticRoutingCentral = staticRoutingHelper.GetStaticRouting (ipv4Central);

staticRoutingCentral->AddHostRouteTo (Ipv4Address (“10.1.1.1”), Ipv4Address (“10.1.3.1”), 1);

staticRoutingCentral->AddHostRouteTo (Ipv4Address (“10.1.2.1”), Ipv4Address (“10.1.4.1”), 1);

// Set up applications (e.g., a UDP echo server and client)

UdpEchoServerHelper echoServer (9);

ApplicationContainer serverApps = echoServer.Install (centralNode.Get (0));

serverApps.Start (Seconds (1.0));

serverApps.Stop (Seconds (20.0));

UdpEchoClientHelper echoClient (Ipv4Address (“10.1.3.2”), 9);

echoClient.SetAttribute (“MaxPackets”, UintegerValue (100));

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

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

ApplicationContainer clientApps = echoClient.Install (branchNodes.Get (0));

clientApps.Start (Seconds (2.0));

clientApps.Stop (Seconds (20.0));

// Change path after 10 seconds

Simulator::Schedule (Seconds (10.0), &ChangePath, branchNodes.Get (0), centralNode.Get (0), Ipv4Address (“10.1.2.2”));

// Enable tracing

pointToPoint.EnablePcapAll (“sdwan-simulation”);

// Run the simulation

Simulator::Run ();

Simulator::Destroy ();

return 0;

}

Explanation

Node creation :

For the SD-WAN, create nodes that represents branches, WAN nodes, and a central node.

Point-to-point link :

To simulate WAN connections, Set up point-to-point links between the nodes.

Internet stack installation :

On the nodes, install the internet stack.

IP address assignment :

Assigns IP addresses to the point-to-point links.

Application setup :

On one node, set up a UDP echo server and on another node, setup a UDP echo client to test connectivity.

Static routing setup :

To simulate path selection, configures static routes. Routes are set up to go through one path.

Path change simulation :

To change the path dynamically during the simulation to simulate SD-WAN behavior, Use a function.

Tracing :

To capture packet information, enable ASCII and pcap tracing for analysis.

Simulation execution :

Run the simulation.

Build and run the simulation

Build and run your script after writing.

./waf build

./waf –run scratch/sdwan-simulation

Analyze the results

You can analyze the results after running the simulation, by generating trace files (sdwan-simulation.tr and sdwan-simulation-0-0.pcap).

Example script for SD-WAN protocol

Below is the example script for your reference: