To simulate a Line Topology in OMNeT++ has needs to generate a network in which the nodes are organized in a straight line, with each node associated only to its immediate neighbours. This kind of topology is usually utilized in simple bus-like communication systems, chain networks, or distributed systems in which each node passes data to the next.
Here’s a step-by-step guide on how to simulate a line topology in OMNeT++ using the INET framework:
Steps to Simulate Line Topology in OMNeT++
- Install OMNeT++ and INET Framework:
Make sure that we have OMNeT++ installed along with the INET framework, that deliver numerous networking modules and simulation components.
- Download and install OMNeT++.
- Download and install the INET Framework.
- Define the Line Topology in NED File:
In a line topology, nodes are organized linearly and each node is associated only to its neighboring nodes. Here’s an example NED file that describes a simple line topology:
network LineTopologyNetwork
{
parameters:
int numNodes = default(5); // Number of nodes in the line
submodules:
// Define the nodes in the line
node[numNodes]: <NodeType> {
@display(“p=100+150*i,100”); // Distribute nodes in a horizontal line
}
connections allowunconnected:
// Connect each node to its immediate neighbor in the line
for i=0..numNodes-2 {
node[i].ethg++ <–> Eth100M <–> node[i+1].ethg++;
}
}
In this example:
- numNodes describes the number of nodes in the line.
- node[numNodes] is an array representing the nodes.
- The for loop creates the point-to-point connections among consecutive nodes.
- Eth100M signifies a 100 Mbps Ethernet link.
- ethg++ are Ethernet gates that manage packet transmission among nodes.
- Define Node Types in NED:
We need to utilize the INET framework’s StandardHost for describing the nodes, or we can generate custom nodes liable on requirements.
Here’s an example of using StandardHost to define a node:
import inet.node.inet.StandardHost;
module NodeType extends StandardHost
{
parameters:
@display(“i=device/laptop”); // Use a laptop icon to represent each node
}
This describes the node type as a StandardHost (from INET), that contain basic networking capabilities.
- Configure the INI File:
In the omnetpp.ini file, we need to setup simulation metrics like traffic patterns, simulation duration, and node configurations.
Here’s a sample configuration for simulating traffic in the line topology:
network = LineTopologyNetwork
sim-time-limit = 30s # Simulation time
# Configuring IP addresses for the nodes
*.node[*].networkLayer.ipv4.address = “10.0.0.x” # Assign IP addresses automatically
# Configuring TCP traffic between Node 0 and Node numNodes-1
*.node[0].numApps = 1
*.node[numNodes-1].numApps = 1
# Define a TCP client on Node 0 and a TCP server on Node numNodes-1 (last node)
*.node[0].app[0].typename = “TcpBasicClientApp”
*.node[0].app[0].connectAddress = “10.0.0.5” # IP address of the last node
*.node[0].app[0].startTime = 1s
*.node[0].app[0].stopTime = 29s
*.node[numNodes-1].app[0].typename = “TcpBasicServerApp” # TCP server on the last node
In this configuration:
- Each node is allocated an IP address automatically.
- Node 0 is configured as a TCP client that transmits data to the last node in the line.
- The last node (Node N) performs as a TCP server to receive the traffic from Node 0.
- Simulate Traffic Using UDP or TCP:
We can produce traffic using either UDP or TCP applications. Below is an instance configuration for simulating UDP traffic among the first and last nodes:
# Configuring UDP traffic from Node 0 to the last node
*.node[0].app[0].typename = “UdpBasicApp”
*.node[0].app[0].destAddresses = “10.0.0.5” # IP of the last node
*.node[0].app[0].destPort = 5000
*.node[0].app[0].packetLength = 1024B
*.node[0].app[0].sendInterval = uniform(1s, 2s)
*.node[0].app[0].startTime = 1s
*.node[0].app[0].stopTime = 29s
# Configure the last node as a UDP sink to receive the packets
*.node[numNodes-1].app[0].typename = “UdpSink”
*.node[numNodes-1].app[0].localPort = 5000
This creates UDP traffic among Node 0 and the last node in the line. The UDP packets will flow linearly via the intermediate nodes.
- Run the Simulation:
- Open OMNeT++ IDE and import project.
- Compile the project and execute the simulation.
- Utilize Qtenv to envision the line topology and track on how packets are routed among the nodes.
During the simulation, we will see traffic flowing from the first node, passing via intermediate nodes, and finally reaching the last node.
- Analyse the Results:
OMNeT++ creates the simulation logs and statistical data that can be evaluated to assess network performance. We need to track the parameters such as:
- Throughput: The data rate among the first and last node.
- Latency: The delay experienced by packets as they travel from one node to another.
- Packet Loss: If any packets are dropped in the course of the transmission.
We need to utilize Plove or Scave to plot graphs and envision the simulation outcomes.
- Advanced Features (Optional):
- Mobility Models: If we need to simulate mobile devices in a line topology (e.g., for a moving chain network), we can implement mobility models to the nodes.
- Error Models: Establish errors in the network to replicate real-world conditions such as packet loss or network failure.
- Routing Protocols: Apply dynamic routing algorithms to replicate intelligent packet routing among nodes.
For example, to add a mobility model to the nodes, we need to set up the INI file like this:
*.node[*].mobility.typename = “RandomWaypointMobility”
*.node[*].mobility.speed = uniform(1mps, 5mps)
This set up adds a random waypoint mobility model, in which nodes move at random speeds.
Summary:
- Define Topology: Utilize a NED file to generate a line topology in which nodes are associated in a straight line.
- Node Types: Utilize INET’s StandardHost or custom node types to signify the devices.
- Traffic Configuration: Replicate the traffic using either TCP or UDP applications among the first and last node.
- Run and Analyse: execute the simulation in OMNeT++ and utilize built-in tools to measure throughput, latency, and packet loss.
In above manual clearly shows about how the Line Topology projects will be simulated and analyse the results in OMNeT++ tool and also we plan to deliver more additional details regarding this process.
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