How to Calculate Network Stalling in omnet++
To calculate the network stalling, has needs includes especially in the framework of streaming or real-time applications, denotes to periods when the playback of media like video or audio is interrupted due to inadequate data being available. It can occur due to network issues like packet loss, or insufficient bandwidth, high latency. In OMNeT++, we can evaluate network stalling by observing the buffer state of the application and identifying when the buffer is reduced, causing a stall.
Steps to Calculate Network Stalling in OMNeT++
- Define Stalling Events:
- A stalling event happens when the application buffer is void, and the playback has to break until more data is received.
- Track the Application Buffer:
- During the simulation, we want to mimic the application buffer, which holds the incoming data before it is played back.
- Observe the buffer level endlessly to detect when it reaches zero or a critical low threshold, which would specify a stall.
- Implement Buffer Management:
- In the OMNeT++ model, execute a mechanism to handle the buffer, where data is inserted as packets are received, and data is removed as it is played back.
double bufferLevel = 0.0; // Buffer level in seconds or bytes
double bufferThreshold = 1.0; // Minimum buffer level before stalling (e.g., 1 second)
simtime_t stallStartTime = -1; // Time when stalling starts
simtime_t totalStallDuration = 0; // Total stalling time
int stallCount = 0; // Count of stalling events
// Function to simulate receiving data
void receiveData(double dataSize) {
bufferLevel += dataSize;
}
// Function to simulate playback
void playback(double playbackRate) {
bufferLevel -= playbackRate * SIMTIME_DBL(simTimeStep()); // Reduce buffer based on playback rate
}
// Function to check buffer and detect stalling
void checkBuffer() {
if (bufferLevel <= bufferThreshold) {
if (stallStartTime == -1) {
// Start stalling
stallStartTime = simTime();
stallCount++;
EV << “Stalling started at ” << simTime() << endl;
}
} else {
if (stallStartTime != -1) {
// End stalling
totalStallDuration += simTime() – stallStartTime;
EV << “Stalling ended at ” << simTime() << “, duration: ” << simTime() – stallStartTime << endl;
stallStartTime = -1;
}
}
}
- Monitor and Record Stalling:
- Frequently verify the buffer status and inform the stalling metrics.
- Record the number of stalling events and the total stalling duration.
virtual void handleMessage(cMessage *msg) override {
// Simulate receiving and playback
receiveData( /* dataSize from message or simulation logic */ );
playback( /* playback rate */ );
// Check if the buffer level is below the threshold
checkBuffer();
// Continue with the rest of the simulation logic
}
virtual void finish() override {
if (stallStartTime != -1) {
// If still stalling at the end, add the last stall duration
totalStallDuration += simTime() – stallStartTime;
}
recordScalar(“Total Stalling Time (s)”, totalStallDuration.dbl());
recordScalar(“Number of Stalling Events”, stallCount);
EV << “Total Stalling Time: ” << totalStallDuration << ” s” << endl;
EV << “Number of Stalling Events: ” << stallCount << endl;
}
- Analyse the Results:
- We can evaluate the recorded stalling metrics to know how network conditions impact playback quality, after the simulation.
- We can compare several network configurations or conditions to see how they have emotional influence the number of stalling events and entire stalling time.
Example Implementation
Given below is a more actual example based on the steps above:
class StreamingApp : public cSimpleModule {
private:
double bufferLevel;
double bufferThreshold;
simtime_t stallStartTime;
simtime_t totalStallDuration;
int stallCount;
protected:
virtual void initialize() override {
bufferLevel = 0.0;
bufferThreshold = 1.0; // 1 second of buffer is required to prevent stalling
stallStartTime = -1;
totalStallDuration = 0;
stallCount = 0;
}
virtual void handleMessage(cMessage *msg) override {
// Simulate receiving 0.5 seconds of data
receiveData(0.5);
// Simulate playback at 1 second per unit time
playback(1.0);
// Check buffer and potentially update stalling metrics
checkBuffer();
delete msg; // Clean up the message
}
void receiveData(double dataSize) {
bufferLevel += dataSize;
EV << “Received data, buffer level: ” << bufferLevel << ” s” << endl;
}
void playback(double playbackRate) {
bufferLevel -= playbackRate * SIMTIME_DBL(simTimeStep());
if (bufferLevel < 0)
bufferLevel = 0;
EV << “Played back, buffer level: ” << bufferLevel << ” s” << endl;
}
void checkBuffer() {
if (bufferLevel <= bufferThreshold) {
if (stallStartTime == -1) {
stallStartTime = simTime();
stallCount++;
EV << “Stalling started at ” << simTime() << endl;
}
} else {
if (stallStartTime != -1) {
totalStallDuration += simTime() – stallStartTime;
EV << “Stalling ended at ” << simTime() << “, duration: ” << simTime() – stallStartTime << endl;
stallStartTime = -1;
}
}
}
virtual void finish() override {
if (stallStartTime != -1) {
totalStallDuration += simTime() – stallStartTime;
}
recordScalar(“Total Stalling Time (s)”, totalStallDuration.dbl());
recordScalar(“Number of Stalling Events”, stallCount);
EV << “Total Stalling Time: ” << totalStallDuration << ” s” << endl;
EV << “Number of Stalling Events: ” << stallCount << endl;
}
};
In this setup, we are delivered useful ideas and procedures to calculate the network Stalling using in OMNeT++. We will offer further details as needed. Omnet-manual.com can assist you with analysis of networking performance. Send us the specifics of your Network Stalling project for more advice. We will share with you the precise information of your projects after examining the data. Get complete project assistance from omnet-manual.com; we have all the tools you need to do your job.