How to Calculate Network Bridging in omnet++
To calculate the network bridging in OMNeT++ has requires to encompass mimicking the behaviour of network bridges, which are devices that associate and filter traffic among various sections of a network. In a simulation, we may need to evaluate how successfully a bridge forwards or filters packets, keeps a forwarding table, and make sure that network traffic is correctly segmented.
Step-by-Step Implementations:
- Understand Network Bridging
A network bridge operates at the data link layer (Layer 2) and is responsible for:
- Forwarding: Transmitting packets to the correct segment based on the MAC address.
- Filtering: Preventing needless traffic from crossing segments.
- Learning: Constructing and maintaining a forwarding table based on the source MAC addresses of packets it receives.
- Set up the Bridge Module
We can make a module that acts as a network bridge in OMNeT++. It should require numerous input and output gates corresponding to the network segments it connects.
Example: Define a Simple Bridge in NED
simple Bridge {
gates:
input in[3];
output out[3];
}
- Implement the Bridge Logic
In OMNeT++ simulation, execute the logic for the bridge, containing the forwarding, filtering, and learning processes.
Example: Implementing a Simple Bridge
#include <map>
#include <omnetpp.h>
using namespace omnetpp;
class Bridge : public cSimpleModule {
private:
std::map<MACAddress, int> forwardingTable; // Forwarding table: MAC address to port index
int numPorts;
protected:
virtual void initialize() override {
numPorts = gateSize(“out”);
}
virtual void handleMessage(cMessage *msg) override {
// Extract MAC address and port info from the message
MACAddress srcAddr = extractSourceMACAddress(msg);
MACAddress destAddr = extractDestMACAddress(msg);
int inputPort = msg->getArrivalGate()->getIndex();
// Learn the source MAC address
learnSourceMACAddress(srcAddr, inputPort);
// Forward or filter the packet
forwardOrFilterPacket(msg, destAddr, inputPort);
}
void learnSourceMACAddress(MACAddress srcAddr, int port) {
// Update the forwarding table with the source address and port
forwardingTable[srcAddr] = port;
EV << “Learned MAC address ” << srcAddr << ” on port ” << port << endl;
}
void forwardOrFilterPacket(cMessage *msg, MACAddress destAddr, int inputPort) {
auto it = forwardingTable.find(destAddr);
if (it != forwardingTable.end()) {
// Destination MAC address found in the forwarding table
int outputPort = it->second;
if (outputPort != inputPort) {
// Forward the packet to the correct output port
send(msg, “out”, outputPort);
EV << “Forwarding packet to port ” << outputPort << endl;
} else {
// Packet destined for the same segment it came from, discard it
EV << “Filtering packet: same port” << endl;
delete msg;
}
} else {
// Destination MAC address not found: broadcast to all ports except the input port
broadcastPacket(msg, inputPort);
}
}
void broadcastPacket(cMessage *msg, int inputPort) {
for (int i = 0; i < numPorts; i++) {
if (i != inputPort) {
cMessage *copy = msg->dup();
send(copy, “out”, i);
}
}
EV << “Broadcasting packet to all ports except port ” << inputPort << endl;
delete msg;
}
MACAddress extractSourceMACAddress(cMessage *msg) {
// Implement logic to extract the source MAC address from the message
// This is a placeholder function and should be implemented based on your message format
return MACAddress(); // Return the source MAC address
}
MACAddress extractDestMACAddress(cMessage *msg) {
// Implement logic to extract the destination MAC address from the message
// This is a placeholder function and should be implemented based on your message format
return MACAddress(); // Return the destination MAC address
}
};
Define_Module(Bridge);
- Simulate and Collect Data
Run the simulation with the bridge module in position. We can watch the behaviour of the bridge, with how the forwarding table evolves over time, and how it forwards and filters packets.
- Measure Bridging Metrics
To calculate the effectiveness of the bridge, we can assess several metrics like:
- Forwarding Efficiency: The percentage of packets properly forwarded to the destination segment.
- Filtering Effectiveness: The percentage of unessential packets effectively filtered.
- Learning Accuracy: The accuracy of the forwarding table (correct MAC address to port mappings).
Example: Tracking Forwarding and Filtering
int packetsForwarded = 0;
int packetsFiltered = 0;
void forwardOrFilterPacket(cMessage *msg, MACAddress destAddr, int inputPort) {
auto it = forwardingTable.find(destAddr);
if (it != forwardingTable.end()) {
int outputPort = it->second;
if (outputPort != inputPort) {
send(msg, “out”, outputPort);
packetsForwarded++;
} else {
delete msg;
packetsFiltered++;
}
} else {
broadcastPacket(msg, inputPort);
packetsForwarded++;
}
}
void finish() override {
recordScalar(“Packets Forwarded”, packetsForwarded);
recordScalar(“Packets Filtered”, packetsFiltered);
}
- Post-Simulation Analysis
Analyse the recorded metrics to calculate the performance of the bridge after running the simulation. We can use OMNeT++’s built-in analysis tools or passing on the data for further processing.
- Example Scenario
In a comprehensive scenario, the bridge would be related to numerous network segments. We should simulate traffic across these segments and watch how the bridge manages the traffic based on the MAC addresses and the learned forwarding table.
network ExampleNetwork {
submodules:
hostA: StandardHost;
hostB: StandardHost;
hostC: StandardHost;
bridge: Bridge;
connections:
hostA.out++ –> bridge.in[0];
bridge.out[0] –> hostA.in++;
hostB.out++ –> bridge.in[1];
bridge.out[1] –> hostB.in++;
hostC.out++ –> bridge.in[2];
bridge.out[2] –> hostC.in++;
}
- Post-Simulation Metrics
The gathered metrics like forwarding accuracy and filtering effectiveness will help to know how well the bridge performs under several conditions and how it impacts overall network performance, after completing the simulation,.
Above the details, we are shown bridge module, metrices, to implement its logic and we learn how to evaluate Network Bridging in OMNeT++. Now we will provide further data depends on your needs.
Kindly share your parameter specifications, and we will support you with Network Bridging using the OMNeT++ tool for your project. Our team of experienced developers is equipped with the right tools to guarantee the successful execution of your tasks. We are committed to enhancing the performance of your network project based on your parameters.