How to Calculate Network Buffer Length in omnet++

To calculate the network buffer length in OMNeT++, we have to define the amount of packets or the total of data currently stored in a buffer at a network node like router, switch, or any other device that lines packets before processing or forwarding them. Assess the performance of the network, detect congestion and make sure that the buffer size is suitable for the traffic load by analyzing the buffer length.

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In the following below, we provided the step-by-step approach to calculate:

Steps to Calculate Network Buffer Length in OMNeT++:

1. Set Up the Network Model:
   • In OMNeT++, Use NED files to state the network topology like setting up nodes with buffers (like routers or switches) and generating traffic sources.
2. Configure Buffering Mechanism:
   • In the network, make certain that the nodes have a buffering mechanism in position. It is achieved by executing custom modules that handles packets lines or use the existing modules from the INET framework.
3. Track Buffer Length:
   • Observe the buffer length over time by executing the mechanisms. The buffer length can be expressed in terms of the count of packets or the total size of the data in the buffer.
4. Calculate and Log Buffer Length:
   • During the simulation, we have to constantly trace and log the buffer length. We can also compute statistics like the average buffer length, maximum buffer length, or buffer occupancy over time.

Example Implementation: Tracking Buffer Length

Below is the example of how to calculate the buffer length in OMNeT++:

#include <omnetpp.h>

#include “inet/queueing/base/PacketQueueBase.h”

using namespace omnetpp;

using namespace inet;

class BufferLengthModule : public PacketQueueBase {

private:

cQueue buffer;                   // Queue to hold packets

simsignal_t bufferLengthSignal;   // Signal to record buffer length

protected:

virtual void initialize() override {

PacketQueueBase::initialize();

bufferLengthSignal = registerSignal(“bufferLengthSignal”);

}

virtual void handleMessage(cMessage *msg) override {

if (msg->isPacket()) {

Packet *packet = check_and_cast<Packet *>(msg);

// Add packet to the buffer

buffer.insert(packet);

// Emit the current buffer length (number of packets)

emit(bufferLengthSignal, buffer.getLength());

// Optionally process or forward the packet

if (canPushSomePacket(packet)) {

buffer.pop();

send(packet, “out”);

}

} else {

delete msg;

}

}

virtual void finish() override {

EV << “Final Buffer Length: ” << buffer.getLength() << ” packets\n”;

}

virtual int getNumPackets() const override {

return buffer.getLength();

}

virtual Packet *getPacket(int index) const override {

return check_and_cast<Packet *>(buffer.get(index));

}

virtual void removePacket(Packet *packet) override {

buffer.remove(packet);

}

virtual void clear() override {

buffer.clear();

}

};

Define_Module(BufferLengthModule);

Explanation:

• BufferLengthModule:
  • buffer: A queue (buffer) to store incoming packets. Before being processed or forwarded, the packets are lined in this actual buffer.
  • bufferLengthSignal: Whenever a change occurs, we have to emit the current buffer length by registering a signal.
• initialize() Function:
  • Initializes the module and registers the buffer length signal.
• handleMessage() Function:
  • Manages incoming packets, injects them into the buffer, and emits the current buffer length (number of packets in the buffer). It also verifies whether a packet can be processed or forwarded and does so if possible.
• finish() Function:
  • At the end of the simulation, we have to logs the final buffer length.
• getNumPackets(), getPacket(), removePacket(), clear() Functions:
  • We need a virtual functions from the PacketQueueBase to manage packets in the buffer by implementing it.

5. Run the Simulation:

• Compile and run the OMNeT++ project. The simulation will trace the buffer length at all node and log the data for analysis.

6. Analyze and Interpret Results:

• The logged buffer length offers insights into the network’s congestion levels and buffer utilization. High buffer lengths may represent congestion, while low buffer lengths may suggest underutilization of network resources.

Additional Considerations:

• Buffer Size Configuration:  To avoid packet loss during buffer overflow, we have to make sure that the buffer size is properly configured for the predicted traffic load.
• Dynamic Traffic Patterns: Consider changing traffic patterns (e.g., bursty traffic) to examine the buffer’s behavior through various conditions.
• Queue Management Algorithms: Execute or use existing queue management algorithms (e.g., RED, FIFO) to see how they distress buffer length and overall network performance.

In this process, we comprehensively provided the valuable information to calculate the network buffer length using INET framework in the OMNeT++. To know more about this calculation, reach out to us so that we can help you.

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