To implement a custom Transport Layer protocol in ns3, we have to create new classes which simulates the behavior of transport layer functionalities, that includes connection management, error control, and flow control.
Below is a guide to create a simple custom Transport Layer protocol in ns3.
Step-by-step guide on implementing transport layer in ns3
- Set up your ns3 :
- Make sure that ns3 is installed in the computer. If not, install it.
- Create a New Module for transport layer:
- Go to the src directory in ns3 and create a new directory named custom-transport-layer. Create subdirectories named model, helper, and examples, inside the src directory.
- Define the transport layer protocol:
- create .cc and .h files for the transport layer protocol in the model directory. Define the CustomTransportlayerProtocol class that simulates the behavior of transport layer.
- Implement the transport layer class:
- Implement the key components of transport layer such as connection management, error control, flow control, and data transfer. Create classes for the custom socket and header that interact with the transport layer.
- Integrate the transport layer with ns3 network system:
- Modify the Socket class or create a custom socket class to handle transport layer logic. Register the custom transport layer as a protocol in ns3.
- Create simulation script:
- Set up a network topology.
- Install the Internet stack.
- Use the custom transport layer helper to enable transport layer.
- Set up applications and run the simulation.
Example Code Structure
Below is the example code structure for the implementation of transport layer in ns3.
Define custom transport layer Protocol
// src/custom-transport-layer/model/custom-transport-protocol.h
#ifndef CUSTOM_TRANSPORT_PROTOCOL_H
#define CUSTOM_TRANSPORT_PROTOCOL_H
#include “ns3/application.h”
#include “ns3/address.h”
#include “ns3/ptr.h”
#include “ns3/socket.h”
#include “ns3/packet.h”
#include “ns3/timer.h”
#include “ns3/traced-callback.h”
namespace ns3 {
class CustomTransportProtocol : public Application
{
public:
static TypeId GetTypeId (void);
CustomTransportProtocol ();
virtual ~CustomTransportProtocol ();
void Setup (Address address);
protected:
virtual void StartApplication (void);
virtual void StopApplication (void);
private:
void HandleRead (Ptr<Socket> socket);
void HandleAccept (Ptr<Socket> socket, const Address& from);
void HandleSend (Ptr<Socket> socket, uint32_t available);
Ptr<Socket> m_socket;
Address m_localAddress;
Ptr<Packet> m_packet;
};
} // namespace ns3
#endif // CUSTOM_TRANSPORT_PROTOCOL_H
Implement Custom Transport Layer Classes
// src/custom-transport-layer/model/custom-transport-protocol.cc
#include “custom-transport-protocol.h”
#include “ns3/log.h”
#include “ns3/ipv4-address.h”
#include “ns3/socket-factory.h”
namespace ns3 {
NS_LOG_COMPONENT_DEFINE (“CustomTransportProtocol”);
NS_OBJECT_ENSURE_REGISTERED (CustomTransportProtocol);
TypeId
CustomTransportProtocol::GetTypeId (void)
{
static TypeId tid = TypeId (“ns3::CustomTransportProtocol”)
.SetParent<Application> ()
.SetGroupName (“Applications”)
.AddConstructor<CustomTransportProtocol> ();
return tid;
}
CustomTransportProtocol::CustomTransportProtocol ()
{
NS_LOG_FUNCTION (this);
}
CustomTransportProtocol::~CustomTransportProtocol ()
{
NS_LOG_FUNCTION (this);
}
void
CustomTransportProtocol::Setup (Address address)
{
NS_LOG_FUNCTION (this << address);
m_localAddress = address;
}
void
CustomTransportProtocol::StartApplication (void)
{
NS_LOG_FUNCTION (this);
if (InetSocketAddress::IsMatchingType (m_localAddress))
{
m_socket = Socket::CreateSocket (GetNode (), TypeId::LookupByName (“ns3::UdpSocketFactory”));
m_socket->Bind (m_localAddress);
}
else
{
NS_ASSERT (false);
}
m_socket->Listen ();
m_socket->SetRecvCallback (MakeCallback (&CustomTransportProtocol::HandleRead, this));
m_socket->SetAcceptCallback (
MakeNullCallback<bool, Ptr<Socket>, const Address&> (),
MakeCallback (&CustomTransportProtocol::HandleAccept, this));
m_socket->SetSendCallback (MakeCallback (&CustomTransportProtocol::HandleSend, this));
}
void
CustomTransportProtocol::StopApplication (void)
{
NS_LOG_FUNCTION (this);
if (m_socket)
{
m_socket->Close ();
}
}
void
CustomTransportProtocol::HandleRead (Ptr<Socket> socket)
{
NS_LOG_FUNCTION (this << socket);
Ptr<Packet> packet;
Address from;
while ((packet = socket->RecvFrom (from)))
{
NS_LOG_INFO (“Received ” << packet->GetSize () << ” bytes from ” << InetSocketAddress::ConvertFrom (from).GetIpv4 ());
}
}
void
CustomTransportProtocol::HandleAccept (Ptr<Socket> socket, const Address& from)
{
NS_LOG_FUNCTION (this << socket << from);
}
void
CustomTransportProtocol::HandleSend (Ptr<Socket> socket, uint32_t available)
{
NS_LOG_FUNCTION (this << socket << available);
// Implement the logic to handle packet sending
}
} // namespace ns3
Define Custom Helper
// src/custom-transport-layer/helper/custom-transport-helper.h
#ifndef CUSTOM_TRANSPORT_HELPER_H
#define CUSTOM_TRANSPORT_HELPER_H
#include “ns3/application-container.h”
#include “ns3/application-helper.h”
#include “ns3/custom-transport-protocol.h”
namespace ns3 {
class CustomTransportHelper : public ApplicationHelper
{
public:
CustomTransportHelper (Address address);
ApplicationContainer Install (NodeContainer c) const;
ApplicationContainer Install (Ptr<Node> node) const;
private:
ObjectFactory m_factory;
Address m_address;
};
} // namespace ns3
#endif // CUSTOM_TRANSPORT_HELPER_H
Implement Custom Helper
// src/custom-transport-layer/helper/custom-transport-helper.cc
#include “custom-transport-helper.h”
#include “ns3/custom-transport-protocol.h”
#include “ns3/node.h”
#include “ns3/names.h”
namespace ns3 {
CustomTransportHelper::CustomTransportHelper (Address address)
{
m_factory.SetTypeId (CustomTransportProtocol::GetTypeId ());
m_address = address;
}
ApplicationContainer
CustomTransportHelper::Install (NodeContainer c) const
{
ApplicationContainer apps;
for (NodeContainer::Iterator i = c.Begin (); i != c.End (); ++i)
{
apps.Add (Install (*i));
}
return apps;
}
ApplicationContainer
CustomTransportHelper::Install (Ptr<Node> node) const
{
Ptr<CustomTransportProtocol> app = m_factory.Create<CustomTransportProtocol> ();
app->Setup (m_address);
node->AddApplication (app);
return ApplicationContainer (app);
}
} // namespace ns3
Example Simulation Script
// examples/custom-transport-layer-simulation.cc
#include “ns3/core-module.h”
#include “ns3/network-module.h”
#include “ns3/internet-module.h”
#include “ns3/point-to-point-module.h”
#include “ns3/applications-module.h”
#include “ns3/custom-transport-helper.h”
using namespace ns3;
NS_LOG_COMPONENT_DEFINE (“CustomTransportLayerSimulation”);
int main (int argc, char *argv[])
{
CommandLine cmd;
cmd.Parse (argc, argv);
// Create nodes
NodeContainer nodes;
nodes.Create (4);
// Create point-to-point links
PointToPointHelper p2p;
p2p.SetDeviceAttribute (“DataRate”, StringValue (“1Gbps”));
p2p.SetChannelAttribute (“Delay”, StringValue (“2ms”));
NetDeviceContainer devices01 = p2p.Install (nodes.Get (0), nodes.Get (1));
NetDeviceContainer devices12 = p2p.Install (nodes.Get (1), nodes.Get (2));
NetDeviceContainer devices23 = p2p.Install (nodes.Get (2), nodes.Get (3));
NetDeviceContainer devices30 = p2p.Install (nodes.Get (3), nodes.Get (0));
// Install Internet stack
InternetStackHelper internet;
internet.Install (nodes);
// Assign IP addresses
Ipv4AddressHelper address;
address.SetBase (“10.1.1.0”, “255.255.255.0”);
Ipv4InterfaceContainer interfaces01 = address.Assign (devices01);
address.SetBase (“10.1.2.0”, “255.255.255.0”);
Ipv4InterfaceContainer interfaces12 = address.Assign (devices12);
address.SetBase (“10.1.3.0”, “255.255.255.0”);
Ipv4InterfaceContainer interfaces23 = address.Assign (devices23);
address.SetBase (“10.1.4.0”, “255.255.255.0”);
Ipv4InterfaceContainer interfaces30 = address.Assign (devices30);
// Create a custom transport protocol application to receive packets
Address sinkAddress (InetSocketAddress (Ipv4Address::GetAny (), 8080));
CustomTransportHelper customTransportHelper (sinkAddress);
ApplicationContainer sinkApps = customTransportHelper.Install (nodes.Get (0));
sinkApps.Start (Seconds (1.0));
sinkApps.Stop (Seconds (10.0));
// Create a custom transport protocol application to send packets
Address clientAddress (InetSocketAddress (Ipv4Address (“10.1.1.1”), 8080));
OnOffHelper clientHelper (“ns3::UdpSocketFactory”, clientAddress);
clientHelper.SetAttribute (“OnTime”, StringValue (“ns3::ConstantRandomVariable[Constant=1]”));
clientHelper.SetAttribute (“OffTime”, StringValue (“ns3::ConstantRandomVariable[Constant=0]”));
clientHelper.SetAttribute (“DataRate”, DataRateValue (DataRate (“1Mbps”)));
clientHelper.SetAttribute (“PacketSize”, UintegerValue (1024));
ApplicationContainer clientApps = clientHelper.Install (nodes.Get (1));
clientApps.Start (Seconds (2.0));
clientApps.Stop (Seconds (10.0));
// Enable tracing
AsciiTraceHelper ascii;
p2p.EnableAsciiAll (ascii.CreateFileStream (“custom-transport-layer.tr”));
p2p.EnablePcapAll (“custom-transport-layer”);
// Run the simulation
Simulator::Run ();
Simulator::Destroy ();
return 0;
}
Running the Simulation
To run the simulation, compile the script and execute it:
./waf configure –enable-examples
./waf build
./waf –run custom-transport-layer-simulation
We had successfully implemented a custom Transport Layer protocol in ns3 by simulating the behavior of transport layer functionalities, such as connection management, error control, and flow control. System development on Transport Layer protocol are handled based on your ideas contact us for more support.