How to implement network scheduling in OMNeT++

To implement network scheduling in OMNeT++ has needs to handle how the network resources are assigned to numerous users or tasks over time. Scheduling is vital in enhancing the performance of a network that make sure fair access, decreasing the delays, and enhancing the overall throughput. This can be completed at several layers of the network stack has involves the MAC layer like time-slot allocation, priority queuing and the application layer like task scheduling.

Steps to Implement Network Scheduling in OMNeT++

1. Install OMNeT++ and INET Framework:
   • Make sure that OMNeT++ and the INET framework are installed. INET provides essential components for simulating various network protocols and scheduling mechanisms.
2. Define the Network Topology:
   • Generate a network topology using a .ned file that involves nodes like hosts, routers, base stations where the scheduling mechanism will be executed.
3. Implement the Scheduling Mechanism:
   • Design or use existing scheduling techniques that distribute resources like bandwidth, time slots to different users or tasks. The sample has contained Round Robin (RR), Weighted Fair Queuing (WFQ), Time Division Multiple Access (TDMA), and priority-based scheduling.
4. Simulate Various Scenarios:
   • Setup the scenarios where the scheduling mechanism is critical, like high traffic loads, real-time communication requirements, or heterogeneous traffic types. Implement the scheduling mechanism to handle the resource allocation efficiently.
5. Configure the Simulation Environment:
   • Use the .ini file to setup the metrics like scheduling intervals, priority levels, and traffic patterns. Adapt these parameters to emulate various network conditions and measure the performance of the scheduling algorithm.
6. Run the Simulation and Analyze Results:
   • Implement the simulation and measure the performance of the scheduling mechanism. Key metrics has contain the throughput, latency, packet loss, fairness, and resource utilization.

Example: Implementing Basic Network Scheduling in OMNeT++

1. Define the Network Topology in a .ned File

// SchedulingNetwork.ned

package networkstructure;

import inet.node.inet.StandardHost;

import inet.node.inet.Router;

network SchedulingNetwork

{

parameters:

int numNodes = default(5);  // Number of nodes in the network

submodules:

router: Router {

@display(“p=300,200”);

numApps = 1;

app[0].typename = “RouterSchedulingApp”;

}

node[numNodes]: StandardHost {

@display(“p=100,200”);

numApps = 1;

app[0].typename = “NodeApp”;

}

connections:

node[*].ethg++ <–> Ethernet100m <–> router.ethg++;

}

2. Implement the Scheduling Mechanism

Generate a C++ class for the router that contains the simple scheduling techniques such as Round Robin (RR) or Priority Queuing (PQ).

#include <omnetpp.h>

#include <inet/applications/base/ApplicationBase.h>

#include <queue>

using namespace omnetpp;

using namespace inet;

class RouterSchedulingApp : public ApplicationBase

{

protected:

std::queue<cPacket *> packetQueue;

int schedulingPolicy;

virtual void initialize(int stage) override;

virtual void handleMessageWhenUp(cMessage *msg) override;

void schedulePacket();

public:

virtual int numInitStages() const override { return NUM_INIT_STAGES; }

};

Define_Module(RouterSchedulingApp);

void RouterSchedulingApp::initialize(int stage)

{

ApplicationBase::initialize(stage);

if (stage == INITSTAGE_APPLICATION_LAYER) {

schedulingPolicy = par(“schedulingPolicy”).intValue();

// Schedule initial packet handling

scheduleAt(simTime() + par(“schedulingInterval”).doubleValue(), new cMessage(“schedulePacket”));

}

}

void RouterSchedulingApp::handleMessageWhenUp(cMessage *msg)

{

if (strcmp(msg->getName(), “schedulePacket”) == 0) {

schedulePacket();

scheduleAt(simTime() + par(“schedulingInterval”).doubleValue(), msg);  // Re-schedule packet handling

} else if (cPacket *pkt = dynamic_cast<cPacket *>(msg)) {

packetQueue.push(pkt);  // Add packet to the queue

} else {

delete msg;

}

}

void RouterSchedulingApp::schedulePacket()

{

if (!packetQueue.empty()) {

cPacket *pkt = packetQueue.front();

packetQueue.pop();

send(pkt, “ethg$o”);  // Send the packet to the destination

EV << “Packet scheduled and sent.” << endl;

} else {

EV << “No packets to schedule.” << endl;

}

}

3. Implement Node Application

Generate a modest application for the nodes that produce traffic to be scheduled by the router.

class NodeApp : public ApplicationBase

{

protected:

virtual void initialize(int stage) override;

virtual void handleMessageWhenUp(cMessage *msg) override;

public:

virtual int numInitStages() const override { return NUM_INIT_STAGES; }

};

Define_Module(NodeApp);

void NodeApp::initialize(int stage)

{

ApplicationBase::initialize(stage);

if (stage == INITSTAGE_APPLICATION_LAYER) {

// Schedule initial packet generation

scheduleAt(simTime() + uniform(1, 2), new cMessage(“sendPacket”));

}

}

void NodeApp::handleMessageWhenUp(cMessage *msg)

{

if (strcmp(msg->getName(), “sendPacket”) == 0) {

cPacket *pkt = new cPacket(“DataPacket”);

send(pkt, “ethg$o”);  // Send packet to the router

scheduleAt(simTime() + uniform(1, 3), msg);  // Re-schedule packet generation

} else {

delete msg;

}

}

4. Configure the Simulation in the .ini File

network = networkstructure.SchedulingNetwork

sim-time-limit = 300s

# Router settings

*.router.app[0].schedulingPolicy = 0;  # 0 for FIFO, 1 for Priority Queueing

*.router.app[0].schedulingInterval = 0.01;  # Time interval between scheduling decisions

# Node settings

*.node[*].app[0].trafficPattern = “uniform”;  # Example traffic pattern

5. Explanation of the Example

• Network Topology (SchedulingNetwork.ned):
  • The network consists of a router and multiple nodes. The router schedules packets from the nodes based on the designated scheduling policy like FIFO or Priority Queuing.
• Scheduling Mechanism (RouterSchedulingApp.cc):
  • The RouterSchedulingApp executes a simple scheduling mechanism that handles the order in which packets are processed and sent. This sample uses a basic FIFO (First-In, First-Out) policy, but it can be expanded to other policies.
• Node Application (NodeApp.cc):
  • The NodeApp creates traffic at random intervals and transfer the packets to the router, which then schedules and forwards them based on the selected policy.
• Simulation Configuration (omnetpp.ini):
  • The .ini file configures the scheduling policy, scheduling interval, and other parameters to emulate numerous network conditions and measure the performance of the scheduling techniques.

Running the Simulation

• Compile project in OMNeT++ IDE and execute the simulation.
• Use OMNeT++’s tools to measure how the scheduling mechanism affects the network performance. The parameters such as  throughput, delay, packet loss, and fairness.

Extending the Example

• Advanced Scheduling Algorithms: Execute more sophisticated scheduling algorithms such as Weighted Fair Queuing (WFQ), Deficit Round Robin (DRR), or Earliest Deadline First (EDF).
• QoS-Aware Scheduling: Establish Quality of Service (QoS) parameters, where various kinds of traffic have numerous priorities or requirements.
• Real-Time Traffic: To emulate real-time traffic like VoIP or video and study how the scheduling mechanism manages time-sensitive data.
• Resource Allocation: Incorporate scheduling with dynamic resource allocation, where the amount of bandwidth or time slots shared to each node is adapted based on demand.
• Load Balancing: Execute load balancing mechanisms where traffic is shared across multiple routers or paths to mitigate congestion.

We had completed executed the network scheduling using the OMNeT++ tool that enhance the network performance to the user. If you need more information on network scheduling we will offered it.

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