How to implement TCP protocols in OMNeT++
To implement a custom TCP protocol in OMNeT++ has numerous steps that embrace to setup the simulation, familiarize the TCP protocol and generate the TCP module then incorporate it with INET framework and validate it. The below is the procedure to implement the TCP protocols in OMNeT++ even after reading if you have any queries we will provide you complete guidance:
Step-by-Step Implementation:
Step 1: Set Up OMNeT++ and INET Framework
- Install OMNeT++: Download and install the latest version of OMNeT++ from the OMNeT++
- Install INET Framework: Download and install the INET framework from the INET repository.
Step 2: Understand TCP Protocol
TCP is a connection-oriented protocol that makes sure that reliable data transmission among the devices. Key concepts include:
- Connection Establishment: Using a three-way handshake (SYN, SYN-ACK, ACK).
- Data Transmission: Guarantee reliable and ordered delivery of data.
- Flow Control: Using windowing mechanisms.
- Congestion Control: Using techniques such as slow start, congestion avoidance, fast retransmit, and fast recovery.
Step 3: Create the TCP Protocol Module
Define the Module in .ned File
Create a .ned file for the TCP protocol module.
simple MyTCP
{
parameters:
double retransmissionTimeout @unit(s) = default(1s);
int maxRetries = default(5);
gates:
input fromAppLayer;
output toAppLayer;
input fromNetworkLayer;
output toNetworkLayer;
}
Implement the Module in C++
Create the corresponding .cc and .h files.
MyTCP.h
#ifndef __MYTCP_H_
#define __MYTCP_H_
#include <omnetpp.h>
#include “inet/networklayer/contract/IRoutingTable.h”
#include “inet/common/INETDefs.h”
using namespace omnetpp;
using namespace inet;
class MyTCP : public cSimpleModule
{
private:
double retransmissionTimeout;
int maxRetries;
cMessage *timeoutMsg;
std::map<int, cMessage*> sentPackets;
int connectionId;
int seqNum;
int ackNum;
protected:
virtual void initialize() override;
virtual void handleMessage(cMessage *msg) override;
void sendPacket();
void processPacket(cMessage *msg);
void handleTimeout();
public:
MyTCP();
virtual ~MyTCP();
};
#endif
MyTCP.cc
#include “MyTCP.h”
Define_Module(MyTCP);
MyTCP::MyTCP()
{
timeoutMsg = nullptr;
}
MyTCP::~MyTCP()
{
cancelAndDelete(timeoutMsg);
for (auto it : sentPackets)
{
cancelAndDelete(it.second);
}
}
void MyTCP::initialize()
{
retransmissionTimeout = par(“retransmissionTimeout”);
maxRetries = par(“maxRetries”);
timeoutMsg = new cMessage(“timeout”);
connectionId = 1;
seqNum = 0;
ackNum = 0;
}
void MyTCP::handleMessage(cMessage *msg)
{
if (msg == timeoutMsg)
{
handleTimeout();
}
else
{
processPacket(msg);
}
}
void MyTCP::sendPacket()
{
cMessage *packet = new cMessage(“TCPData”);
packet->setKind(TCP_C_SEND);
packet->addPar(“seqNum”) = seqNum;
sentPackets[seqNum] = packet;
send(packet, “toNetworkLayer”);
seqNum++;
}
void MyTCP::processPacket(cMessage *msg)
{
int receivedAckNum = msg->par(“ackNum”);
if (sentPackets.find(receivedAckNum) != sentPackets.end())
{
cancelAndDelete(sentPackets[receivedAckNum]);
sentPackets.erase(receivedAckNum);
}
if (msg->getKind() == TCP_I_DATA)
{
send(msg->dup(), “toAppLayer”);
delete msg;
sendPacket();
}
}
void MyTCP::handleTimeout()
{
for (auto it : sentPackets)
{
send(it.second->dup(), “toNetworkLayer”);
}
scheduleAt(simTime() + retransmissionTimeout, timeoutMsg);
}
Step 4: Integrate with Simulation Model
Incoporate custom TCP module into a network simulation model.
Network Configuration .ned File
network MyTCPNetwork
{
submodules:
host1: StandardHost {
parameters:
@display(“p=100,100”);
}
host2: StandardHost {
parameters:
@display(“p=300,100”);
}
connections:
host1.pppg++ <–> { @display(“m=100,100”); } <–> host2.pppg++;
}
omnetpp.ini Configuration
network = MyTCPNetwork
*.host*.pppg[*].queue.typename = “DropTailQueue”
*.host*.ipv4.routingTable = “inet.networklayer.routing.manet.Router”
*.host*.networkLayer.networkProtocol.typename = “IPv4NetworkLayer”
*.host*.transportLayer.tcp = “MyTCP”
*.host*.application[*].typename = “UDPBasicApp”
*.host*.application[*].destAddresses = “host1” // Set destination as needed
*.host*.application[*].destPort = 2000
*.host*.application[*].startTime = uniform(0s, 10s)
*.host*.application[*].sendInterval = uniform(1s, 2s)
*.host*.application[*].packetLength = 512B
Step 5: Test and Debug
- Run Simulations: implement simulations to test the characteristics of custom TCP module under various network conditions.
- Analyze Results: Verify the correctness and performance of implementation.
- Debugging: Use OMNeT++’s debugging tools to troubleshoot any issues.
Here, we completely implement the TCP protocol in OMNeT++ tools that setup the simulation and then generate the TCP module it incorporate the INET framework and evaluated. We also share the more data regarding the TCP protocol.