How to Begin Implement Session Initiation Protocol in NS3

To start implementing a Session Initiation Protocol (SIP) using NS3 which requires making a custom application, which simulates the signaling behavior of SIP to introduces, change, and end the multimedia sessions. SIP is typically utilized for VoIP, video conferencing, and other multimedia interaction.

Below is an ordered mechanism to execute SIP in NS3:

Steps to Begin Implement Session Initiation Protocol in NS3

Step 1: Understand SIP Basics

1. Core SIP Concepts:
   • SIP is a signaling protocol for launching, handling and ending the sessions.
   • Following is a crucial objects:
     • User Agents (UA): Induct and inherit the demands.
     • Registrar Servers: It handles the user locations.
     • Proxy Servers: Transmit the SIP requests.
   • General techniques:
     • INVITE: Introduce a session.
     • ACK: Verify session establishment.
     • BYE: End a session.
     • REGISTER: Enter a UA including a registrar.
2. Simulation Goals:
   • Replicate a simple SIP workflow:
     • Enter UAs in addition to a server.
     • Introduce a session such as INVITE, ACK, and BYE.
   • Study signaling, without media transfer.

Step 2: Set Up NS3

1. Install NS3:

git clone https://gitlab.com/nsnam/ns-3-dev.git

cd ns-3-dev

./ns3 configure –enable-examples –enable-tests

./ns3 build

1. Verify Installation: Execute a sample installation script:

./ns3 run examples/tutorial/first

Step 3: Plan SIP Implementation

1. Components:
   • SIP User Agent (UA): Replicates the SIP clients for instance phones or softphones.
   • SIP Server: It manages registering and call signaling.
   • Message Exchange: Replicate the SIP interaction using sockets.
2. Simplified SIP Workflow:
   • UAs enrol with the SIP server using REGISTER method.
   • UAs started a session by INVITE method.
   • UAs end the session with BYE method.

Step 4: Implement SIP Components

Step 4.1: Define the SIP Server

Make a SIP class for the server application:

#include “ns3/application.h”

#include “ns3/socket.h”

#include “ns3/address.h”

using namespace ns3;

class SipServer : public Application {

public:

static TypeId GetTypeId(void);

SipServer();

virtual ~SipServer();

private:

virtual void StartApplication() override;

virtual void StopApplication() override;

void HandleRequest(Ptr<Socket> socket);

Ptr<Socket> m_socket;

std::map<std::string, Address> m_registeredUAs; // UA registrations

};

Step 4.2: Define the SIP User Agent

For the client application, make a class:

#include “ns3/application.h”

#include “ns3/socket.h”

using namespace ns3;

class SipUserAgent : public Application {

public:

static TypeId GetTypeId(void);

SipUserAgent();

virtual ~SipUserAgent();

void SetServer(Address serverAddress);

private:

virtual void StartApplication() override;

virtual void StopApplication() override;

void RegisterWithServer();

void InitiateSession();

void TerminateSession();

Ptr<Socket> m_socket;

Address m_serverAddress;

};

Step 4.3: Implement SIP Logic

• SIP Server Logic:
  • Manage the receiving SIP logic messages.

void SipServer::StartApplication() {

m_socket = Socket::CreateSocket(GetNode(), TypeId::LookupByName(“ns3::UdpSocketFactory”));

InetSocketAddress local = InetSocketAddress(Ipv4Address::GetAny(), 5060); // SIP Port

m_socket->Bind(local);

m_socket->SetRecvCallback(MakeCallback(&SipServer::HandleRequest, this));

}

void SipServer::StopApplication() {

if (m_socket) {

m_socket->Close();

}

}

void SipServer::HandleRequest(Ptr<Socket> socket) {

Ptr<Packet> packet = socket->Recv();

std::string message = std::string((char *)packet->PeekData(), packet->GetSize());

std::cout << “Received SIP message: ” << message << std::endl;

// Parse and handle SIP methods (REGISTER, INVITE, BYE)

if (message.find(“REGISTER”) == 0) {

std::string ua = message.substr(9); // Example UA parsing

m_registeredUAs[ua] = socket->GetPeerName();

socket->Send(Create<Packet>((uint8_t *)”200 OK”, 6));

} else if (message.find(“INVITE”) == 0) {

// Handle INVITE and forward to the recipient

socket->Send(Create<Packet>((uint8_t *)”200 OK”, 6));

}

}

• SIP User Agent Logic:
  • Enrol with the server and replicate the session origination and end.

void SipUserAgent::StartApplication() {

m_socket = Socket::CreateSocket(GetNode(), TypeId::LookupByName(“ns3::UdpSocketFactory”));

m_socket->Connect(m_serverAddress);

Simulator::Schedule(Seconds(1.0), &SipUserAgent::RegisterWithServer, this);

}

void SipUserAgent::StopApplication() {

if (m_socket) {

m_socket->Close();

}

}

void SipUserAgent::RegisterWithServer() {

Ptr<Packet> packet = Create<Packet>((uint8_t *)”REGISTER UA1″, 12);

m_socket->Send(packet);

}

void SipUserAgent::InitiateSession() {

Ptr<Packet> packet = Create<Packet>((uint8_t *)”INVITE UA2″, 10);

m_socket->Send(packet);

}

void SipUserAgent::TerminateSession() {

Ptr<Packet> packet = Create<Packet>((uint8_t *)”BYE”, 3);

m_socket->Send(packet);

}

Step 5: Simulate SIP Communication

Design a network topology and then install SIP applications.

Simulation Script:

int main(int argc, char *argv[]) {

NodeContainer nodes;

nodes.Create(3); // 1 server, 2 UAs

PointToPointHelper p2p;

p2p.SetDeviceAttribute(“DataRate”, StringValue(“10Mbps”));

p2p.SetChannelAttribute(“Delay”, StringValue(“2ms”));

NetDeviceContainer devices = p2p.Install(nodes.Get(0), nodes.Get(1));

devices.Add(p2p.Install(nodes.Get(0), nodes.Get(2)));

InternetStackHelper stack;

stack.Install(nodes);

Ipv4AddressHelper address;

address.SetBase(“10.1.1.0”, “255.255.255.0”);

Ipv4InterfaceContainer interfaces = address.Assign(devices);

// Set up SIP Server

Ptr<SipServer> server = CreateObject<SipServer>();

nodes.Get(0)->AddApplication(server);

server->SetStartTime(Seconds(1.0));

server->SetStopTime(Seconds(20.0));

// Set up SIP User Agent 1

Ptr<SipUserAgent> ua1 = CreateObject<SipUserAgent>();

ua1->SetServer(InetSocketAddress(interfaces.GetAddress(0), 5060));

nodes.Get(1)->AddApplication(ua1);

ua1->SetStartTime(Seconds(2.0));

ua1->SetStopTime(Seconds(20.0));

// Set up SIP User Agent 2

Ptr<SipUserAgent> ua2 = CreateObject<SipUserAgent>();

ua2->SetServer(InetSocketAddress(interfaces.GetAddress(0), 5060));

nodes.Get(2)->AddApplication(ua2);

ua2->SetStartTime(Seconds(2.0));

ua2->SetStopTime(Seconds(20.0));

Simulator::Run();

Simulator::Destroy();

return 0;

}

Step 6: Test and Debug

1. Enable Logging:

export NS_LOG=”SipServer=level_all|prefix_time,SipUserAgent=level_all|prefix_time”

./ns3 run my-simulation

1. Validate Behavior:
   • Confirm message flow among the UAs and the server.
   • Check replies for instance, “200 OK”.

Step 7: Extend and Optimize

1. Enhancements:
   • Integrate support for additional SIP mechanisms such as OPTIONS, CANCEL.
   • Replicate the proxy servers for message transmitting.
2. Performance Testing:
   • Experiment with numerous UAs and servers.
   • For traffic analysis, make use of FlowMonitor.

We have provided an outlined structure for implementing and extending the Session Initiation Protocol using NS3 environment. If you would like additional insights or in-depth explanations for any section, feel free to ask!