To simulate Least-Cost Routing using OMNeT++, which comprises executing a routing algorithm that computes paths according to the parameters such as distance, delay, bandwidth, or a combination of several factors, in which each link in the network is allocated a “cost.” The significant aim is to calculate the path among source and destination, which reduces the total cost. Algorithms such as Dijkstra’s shortest path algorithm or Bellman-Ford can be utilized for least-cost routing within networks.
Below is a step-by-step instruction to replicate Least-Cost Routing in OMNeT++ using the INET framework, in which we concentrate on a scenario, which computes the shortest path rely on customizable link costs.
Steps to Simulate Least Cost Routing Projects in OMNeT++
- Install OMNeT++ and INET Framework
- Download OMNeT++:
- We can download and install OMNeT++ from the official website.
- Install INET Framework:
- INET offers support for numerous routing protocols and permits the configuration of custom routing metrics.
- Clone the INET repository:
git clone https://github.com/inet-framework/inet.git
-
- Import the INET project into OMNeT++ using File > Import > Existing Projects into Workspace, and choose the inet directory.
- Build the project by right-clicking the inet project and choosing Build Project.
- Define the Network Topology in NED
We will require to describe a network topology in which we can apply the least-cost routing strategy. The NED file describes routers, links among them, and customizable link costs.
Example NED File for Least-Cost Routing (LeastCostRoutingNetwork.ned):
package leastcostrouting;
import inet.node.inet.Router;
import inet.node.inet.StandardHost;
import inet.linklayer.ethernet.EthernetInterface;
import inet.networklayer.configurator.ipv4.Ipv4NetworkConfigurator;
network LeastCostRoutingNetwork
{
parameters:
int numRouters = 4; // Define the number of routers
submodules:
configurator: Ipv4NetworkConfigurator {
@display(“p=50,50”);
}
host1: StandardHost {
@display(“p=50,50”);
}
host2: StandardHost {
@display(“p=400,50”);
}
router[numRouters]: Router {
@display(“p=100+100*i,150”);
}
connections allowunconnected:
host1.ethg++ <–> EthernetInterface <–> router[0].ethg++;
router[0].ethg++ <–> EthernetInterface <–> router[1].ethg++;
router[1].ethg++ <–> EthernetInterface <–> router[2].ethg++;
router[2].ethg++ <–> EthernetInterface <–> router[3].ethg++;
router[3].ethg++ <–> EthernetInterface <–> host2.ethg++;
}
Explanation:
- StandardHost: Denotes the source and destination nodes, which transmit and receive traffic.
- Router: Signifies the routers that will forward packets according to the least-cost routing algorithm.
- EthernetInterface: Wired Ethernet connections among routers and hosts.
- Ipv4NetworkConfigurator: Automatically allocates an IP addresses to the hosts and routers.
- Configure the Least-Cost Routing Protocol in omnetpp.ini
In this section, we will set up the routing protocol to utilize least-cost paths rely on customizable link costs. We will change the OSPF (Open Shortest Path First) protocol that is depends on Dijkstra’s algorithm, to mimic least-cost routing by changing link metrics.
Example omnetpp.ini Configuration:
[General]
network = LeastCostRoutingNetwork
sim-time-limit = 300s
# IP Address Configuration
*.host1.ipv4.address = “10.0.0.1”
*.host1.ipv4.netmask = “255.255.255.0”
*.host2.ipv4.address = “10.0.0.2”
*.host2.ipv4.netmask = “255.255.255.0”
# Configure OSPF (Dijkstra-based Least-Cost Routing)
*.router[*].hasOspf = true
*.router[*].ospfRouter.routerId = “auto”
*.router[*].ospfRouter.interfaceTableModule = “^.interfaceTable”
*.router[*].ospfRouter.area[0].interface[0].cost = 1 # Assign custom link cost
*.router[*].ospfRouter.area[0].interface[1].cost = 2 # Different cost for a different link
*.router[*].ospfRouter.area[0].interface[2].cost = 1 # You can set various costs
*.router[*].ospfRouter.area[0].interface[3].cost = 4
# Traffic Configuration (UDP Traffic Generation)
*.host1.numApps = 1
*.host1.app[0].typename = “UdpBasicApp”
*.host1.app[0].destAddresses = “10.0.0.2” # Send traffic to Host2
*.host1.app[0].destPort = 5000
*.host1.app[0].messageLength = 1024B
*.host1.app[0].sendInterval = exponential(1s)
*.host2.numApps = 1
*.host2.app[0].typename = “UdpSink” # Host2 is the UDP receiver
*.host2.app[0].localPort = 5000
# OSPF Parameters
*.**.ospfRouter.helloInterval = 5s # Interval for Hello messages
*.**.ospfRouter.routerDeadInterval = 20s
*.**.ospfRouter.updateInterval = 10s # Update interval for recalculating shortest paths
Explanation:
- OSPF Configuration: For each router is set up with OSPF (Open Shortest Path First) that uses Dijkstra’s algorithm to calculate the least-cost path.
- Custom Link Costs: The cost parameter is allocated to each router interface, denoting the cost of sending traffic over that link. OSPF will compute the shortest path according to these costs.
- Traffic Generation: Host1 transmits UDP traffic to Host2 via the routers, and Host2 receives the traffic.
- OSPF Parameters: Sets the Hello interval, dead interval, and update interval to manage how often OSPF exchanges routing data and updates the routing tables.
- Run the Simulation
- Build the Project:
- Right-click on the OMNeT++ project and choose Build Project to compile the simulation.
- Run the Simulation:
- Right-click on omnetpp.ini and choose Run As > OMNeT++ Simulation.
- Utilize the Qtenv graphical interface to monitor how OSPF computes the least-cost path among the source and destination, rely on the configured link costs.
- Analyze the Results
When the simulation is complete then we can examine the following significant features of least-cost routing:
- Routing Table Convergence:
- Monitor how OSPF computes the least-cost paths rely on the specified link costs. For each router will swap routing data with its neighbours and update its routing table consequently.
- Traffic Flow:
- Check that traffic from Host1 to Host2 is routed along the least-cost path depends on the costs are allocated to each link.
- OSPF Control Traffic:
- Observe the OSPF Hello messages and Link-State Advertisements (LSAs) exchanged among the routers to conserve up-to-date routing data.
- Performance Metrics:
- End-to-End Delay: Calculates the delay in sending packets from Host1 to Host2.
- Throughput: Investigate the overall data throughput among the hosts.
- Packet Delivery Ratio: Verify if any packets were lost because of routing issues or network failures.
- Simulate Dynamic Network Conditions
We can replicate several dynamic network conditions to monitor how the least-cost routing adapts:
- Link Failures:
- Replicate a link failure by disabling a link among two routers and monitor how OSPF recalculates the least-cost paths to reroute traffic.
# Disable a link to simulate link failure
*.router[1].ethg[1].disable = true
- Congestion:
- Launch several traffic flows to replicate congestion and monitor how OSPF adjusts to high traffic loads by selecting paths with lower cost.
- Link Cost Changes:
- Dynamically modify the cost of specific links in the course of the simulation and monitor how OSPF updates the routing tables and reroutes traffic consequently.
# Change the cost of a link during simulation
*.router[2].ospfRouter.area[0].interface[0].cost = 10
- Extend the Simulation
- QoS-based Least-Cost Routing:
- Execute Quality of Service (QoS) parameters like bandwidth, delay, and jitter as link costs, and change the OSPF routing algorithm to prioritize these parameters.
- Larger Networks:
- Extend the network topology with more routers and hosts to investigate the scalability of the least-cost routing algorithm.
- Custom Routing Protocol:
- If OSPF does not encounter requires then we can be executed a custom routing protocol that uses particular least-cost algorithm (e.g., multi-metric routing) by making custom C++ modules.
- Compare with Other Routing Algorithms:
- Compare the performance of least-cost routing (OSPF) with other routing algorithms like RIP (Bellman-Ford) or BGP such as convergence time, overhead, and route optimality.
Above stepwise procedure was executed for Least Cost Routing projects and it was simulated and analysed utilizing the simulation tool OMNeT++. We will help you with simulation on your Least Cost Routing Projects using OMNeT++. You can expect great simulations and research ideas from us. We can also create custom projects just for you. Plus, we promise to deliver everything on time with a short explanation.
