To implement a ring topology in ns3, we need to create a network where each node is connected to two other nodes, forming a closed loop. Here is an interesting guide to set up a ring topology in ns3.
Steps to implement ring topology
- Set Up ns3:
- Make sure that ns3 is installed in the computer. If not, install it.
- Create the Nodes:
- To represent devices in the ring network, create a set of nodes.
- Set Up the Point-to-Point Channels:
- To connect each node to its two neighbours, forming a ring, use point-to-point helpers.
- Install Network Stack:
- On all nodes, install the internet stack.
- Assign IP Addresses:
- To the nodes connected to the point-to-point links, assign IP addresses.
- Set Up Applications:
- To generate traffic and demonstrate communication between nodes, install applications.
Example code
Here is an example to set up a basic ring topology 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;
NS_LOG_COMPONENT_DEFINE (“RingTopologyExample”);
int main (int argc, char *argv[])
{
CommandLine cmd;
cmd.Parse (argc, argv);
// Create nodes
NodeContainer nodes;
nodes.Create (5); // Create 5 nodes for the ring
// Create point-to-point links to form a ring
PointToPointHelper pointToPoint;
pointToPoint.SetDeviceAttribute (“DataRate”, StringValue (“100Mbps”));
pointToPoint.SetChannelAttribute (“Delay”, TimeValue (NanoSeconds (6560)));
NetDeviceContainer devices;
InternetStackHelper stack;
stack.Install (nodes);
Ipv4AddressHelper address;
for (uint32_t i = 0; i < nodes.GetN (); ++i)
{
NetDeviceContainer link;
if (i == nodes.GetN () – 1)
{
// Connect the last node to the first node to complete the ring
link = pointToPoint.Install (NodeContainer (nodes.Get (i), nodes.Get (0)));
}
else
{
// Connect the current node to the next node
link = pointToPoint.Install (NodeContainer (nodes.Get (i), nodes.Get (i + 1)));
}
devices.Add (link);
std::ostringstream subnet;
subnet << “10.1.” << i + 1 << “.0”;
address.SetBase (subnet.str ().c_str (), “255.255.255.0”);
address.Assign (link);
}
// Enable routing
Ipv4GlobalRoutingHelper::PopulateRoutingTables ();
// Create a UDP server on node 1
UdpServerHelper udpServer (9);
ApplicationContainer serverApp = udpServer.Install (nodes.Get (1));
serverApp.Start (Seconds (1.0));
serverApp.Stop (Seconds (10.0));
// Create a UDP client on node 0
UdpClientHelper udpClient (Ipv4Address (“10.1.2.1”), 9); // Assuming node 1’s IP is 10.1.2.1
udpClient.SetAttribute (“MaxPackets”, UintegerValue (320));
udpClient.SetAttribute (“Interval”, TimeValue (MilliSeconds (50)));
udpClient.SetAttribute (“PacketSize”, UintegerValue (1024));
ApplicationContainer clientApp = udpClient.Install (nodes.Get (0));
clientApp.Start (Seconds (2.0));
clientApp.Stop (Seconds (10.0));
// Enable packet capture
pointToPoint.EnablePcapAll (“ring-topology”);
// Enable logging
LogComponentEnable (“UdpClient”, LOG_LEVEL_INFO);
LogComponentEnable (“UdpServer”, LOG_LEVEL_INFO);
Simulator::Run ();
Simulator::Destroy ();
return 0;
}
Explanation
- Setup:
Created five nodes connected by point-to-point links.
- Point-to-Point Links:
To connect each node to its two neighbours, forming a ring, Point-to-point links are created. The data rate and delay are configured for the links.
- Network Stack:
On all nodes, the internet stack is installed.
- IP Addresses:
To the nodes, IP addresses are assigned connected by the point-to-point links.
- Applications:
On one node (node 1), A UDP server is installed and a UDP client is installed on another node (node 0) to generate traffic and demonstrate communication.
- Packet Capture:
To observe network traffic, packet capture is enabled for the point-to-point links.
- Logging:
To provide detailed output during the simulation, logging is enabled for the UDP client and server applications.
Running the Simulation
Compile and run the simulation using the following commands:
./waf configure
./waf build
./waf –run ring-topology-example
Replace ring-topology-example with the actual name of your script file.
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