To simulate a Hierarchical Topology utilizing OMNeT++, which contains making a network including several layers of nodes, in which each layer denotes a distinct level of hierarchy. In this topology, lower-level nodes communicate with higher-level nodes, and the communication among distinct layers is normally handled via gateways or routers.
A hierarchical topology is generally utilized in large networks, like corporate networks, in which the lower layers denote end-user devices, and higher layers signify servers, routers, or core networks. The following is a common approach on how we can simulate a Hierarchical Topology in OMNeT++ using the INET framework:
Steps to Simulate a Hierarchical Topology in OMNeT++
- Install OMNeT++ and INET Framework:
Make sure OMNeT++ and the INET framework are installed. The INET framework offers modules for distinct kinds of nodes and network layers that are helpful for making hierarchical topologies.
- We can download and install OMNeT++.
- Download and install the INET Framework.
- Define Hierarchical Topology in NED File:
In a hierarchical topology, nodes are classified into distinct layers (e.g., edge layer, distribution layer, and core layer). Here’s an instance of a NED file, which describes a simple hierarchical network with three layers.
network HierarchicalNetwork
{
parameters:
int numEdgeNodes = default(3); // Number of edge nodes
int numDistributionNodes = default(2); // Number of distribution nodes
int numCoreNodes = default(1); // Number of core nodes
submodules:
// Define edge nodes (bottom level of the hierarchy)
edgeNode[numEdgeNodes]: <EdgeNodeType> {
@display(“p=100+100*i,300”);
}
// Define distribution nodes (middle level of the hierarchy)
distributionNode[numDistributionNodes]: <DistributionNodeType> {
@display(“p=150+200*i,200”);
}
// Define core nodes (top level of the hierarchy)
coreNode[numCoreNodes]: <CoreNodeType> {
@display(“p=250,100”);
}
connections allowunconnected:
// Connect edge nodes to distribution nodes
for i=0..numEdgeNodes-1 {
edgeNode[i].ethg++ <–> Eth100M <–> distributionNode[i % numDistributionNodes].ethg++;
}
// Connect distribution nodes to the core node
for i=0..numDistributionNodes-1 {
distributionNode[i].ethg++ <–> Eth1G <–> coreNode[0].ethg++;
}
}
In this example:
- Edge nodes denote devices such as end-user devices (e.g., PCs or IoT devices).
- Distribution nodes perform as intermediate routers or switches, which combined traffic from edge nodes.
- Core nodes signify the central or core network components, like high-performance routers.
- Eth100M and Eth1G denotes Ethernet links with 100 Mbps and 1 Gbps bandwidth, correspondingly.
- ethg++ describes the Ethernet gates for each node.
- Define Node Types in NED:
We can be used INET’s StandardHost for the distinct kinds of nodes (edge, distribution, core), or we can tailor each type of node.
For instance, define the edge, distribution, and core nodes as follows:
import inet.node.inet.StandardHost;
module EdgeNodeType extends StandardHost
{
parameters:
@display(“i=device/laptop”); // Edge node icon
}
module DistributionNodeType extends StandardHost
{
parameters:
@display(“i=device/switch”); // Distribution node icon
}
module CoreNodeType extends StandardHost
{
parameters:
@display(“i=device/router”); // Core node icon
}
This configure uses distinct icons to visually distinguish the edge, distribution, and core nodes.
- Configure the INI File:
The omnetpp.ini file controls the simulation parameters, such as the number of nodes, traffic patterns, and simulation duration.
Here’s an instance configuration for simulating traffic among the edge nodes and the core node:
network = HierarchicalNetwork
sim-time-limit = 50s # Set simulation time
# Configure IP addresses for all nodes
*.edgeNode[*].networkLayer.ipv4.address = “10.0.0.x”
*.distributionNode[*].networkLayer.ipv4.address = “10.0.1.x”
*.coreNode[*].networkLayer.ipv4.address = “10.0.2.x”
# Configure traffic (TCP) from edge nodes to the core node
*.edgeNode[0].numApps = 1
*.coreNode[0].numApps = 1
# Define a TCP client on edgeNode[0] and a TCP server on coreNode[0]
*.edgeNode[0].app[0].typename = “TcpBasicClientApp”
*.edgeNode[0].app[0].connectAddress = “10.0.2.1” # Core node IP
*.edgeNode[0].app[0].startTime = 2s
*.edgeNode[0].app[0].stopTime = 48s
*.coreNode[0].app[0].typename = “TcpBasicServerApp” # TCP server on the core node
In this configuration:
- IP addresses are allocated to each layer (edge, distribution, core).
- A TCP client is created on edgeNode[0] to transmit data to the core node.
- A TCP server is made on the core node to receive traffic.
- Traffic Generation Using TCP or UDP:
We can mimic traffic among the edge and core layers using either TCP or UDP. Here’s how to set up UDP traffic in the INI file:
# Configure UDP traffic from edgeNode[0] to the core node
*.edgeNode[0].app[0].typename = “UdpBasicApp”
*.edgeNode[0].app[0].destAddresses = “10.0.2.1” # Core node IP
*.edgeNode[0].app[0].destPort = 5000
*.edgeNode[0].app[0].packetLength = 1024B
*.edgeNode[0].app[0].sendInterval = uniform(1s, 2s)
*.edgeNode[0].app[0].startTime = 2s
*.edgeNode[0].app[0].stopTime = 48s
# Configure the core node to act as a UDP sink
*.coreNode[0].app[0].typename = “UdpSink”
*.coreNode[0].app[0].localPort = 5000
This configuration makes UDP traffic from the edge node to the core node at an arbitrarily distributed interval.
- Run the Simulation:
- We can open OMNeT++ IDE, compile the project, and run the simulation.
- Utilize Qtenv to visualize the hierarchical network and monitor packet transmissions among the layers.
We will be monitored traffic flowing from the edge nodes, via the distribution layer, and up to the core node.
- Analyze the Results:
OMNeT++ creates detailed logs and statistics data in the course of the simulation. We can observe the following:
- Throughput: Assess the data rate among distinct layers (e.g., from edge to core).
- Latency: Calculate the delay in sending packets across distinct layers.
- Packet Loss: Verify for lost packets as they navigate several layers.
We can be used Scave or Plove to envision these metrics, making a graphs or transporting data for further analysis.
- Advanced Features (Optional):
- QoS (Quality of Service): We can replicate Quality of Service mechanisms to prioritize traffic among the layers.
- Energy Models: Utilize energy models to mimic the energy consumption of edge devices (useful in IoT networks).
- Mobility Models: Apply mobility models to edge nodes if the network comprises mobile devices (e.g., wireless hierarchical networks).
- Routing Protocols: Execute the routing protocols such as OSPF or BGP among distribution and core layers to replicate more complex routing.
Example of Mobility Model:
*.edgeNode[*].mobility.typename = “RandomWaypointMobility”
*.edgeNode[*].mobility.speed = uniform(1mps, 5mps)
This configuration applies a mobility model to edge nodes, replicating mobile devices, which can move in the network.
Summary:
- Topology Definition: Utilize NED to make a hierarchical topology with edge, distribution, and core layers.
- Node Configuration: Describe distinct kinds of nodes (e.g., edge, distribution, core) using StandardHost or custom modules.
- Traffic Configuration: Use either TCP or UDP to generate traffic among the layers.
- Run and Analyze: We can run the simulation, and use OMNeT++’s analysis tools to calculate throughput, latency, and packet loss.
Here, we had thoroughly illustrated significant concepts that supports you to execute and simulate the Hierarchical Topology within OMNeT++ using INET framework. You want further informations on this projects, we will be shared.
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