To implement the Open Shortest Path First (OSPF) in ns-3 has several steps that can broadly use for interior gateway protocol that can use link-state routing to define the best path among nodes.
Here is the step by procedures on how to implement the OSPF in ns3.
Prerequisites
- ns-3 Installation: Make sure ns-3 is installed in the computer.
- C++ Programming: basic understanding of C++ is needed.
- Understanding of ns-3: Familiarity with ns-3 modules and basic simulation scripts.
Steps to Implement OSPF in ns-3
- Set Up the Development Environment
Make certain that you have installed ns3.if not then download it from ns3 official website.
- Create a New OSPF Module
Navigate to the src directory in ns-3 and create a new directory for your OSPF module.
cd ns-3.XX/src
mkdir ospf
cd ospf
mkdir model helper test
3. Define OSPF Classes and Headers
Create header and implementation files for OSPF in the model directory.
ospf-routing-protocol.h
#ifndef OSPF_ROUTING_PROTOCOL_H
#define OSPF_ROUTING_PROTOCOL_H
#include “ns3/ipv4-routing-protocol.h”
#include “ns3/ipv4-address.h”
#include “ns3/timer.h”
#include “ns3/node.h”
#include “ns3/socket.h”
#include “ns3/net-device.h”
#include “ns3/packet.h”
#include “ns3/nstime.h”
#include <map>
namespace ns3 {
class OspfRoutingProtocol : public Ipv4RoutingProtocol {
public:
static TypeId GetTypeId (void);
OspfRoutingProtocol ();
virtual ~OspfRoutingProtocol ();
virtual void DoDispose (void);
// Implement required virtual functions from Ipv4RoutingProtocol
virtual Ptr<Ipv4Route> RouteOutput (Ptr<Packet> p, const Ipv4Header &header,
Ptr<NetDevice> oif,
Socket::SocketErrno &sockerr);
virtual bool RouteInput (Ptr<const Packet> p, const Ipv4Header &header,
Ptr<const NetDevice> idev,
UnicastForwardCallback ucb,
MulticastForwardCallback mcb,
LocalDeliverCallback lcb,
ErrorCallback ecb);
virtual void NotifyInterfaceUp (uint32_t interface);
virtual void NotifyInterfaceDown (uint32_t interface);
virtual void NotifyAddAddress (uint32_t interface, Ipv4InterfaceAddress address);
virtual void NotifyRemoveAddress (uint32_t interface, Ipv4InterfaceAddress address);
virtual void SetIpv4 (Ptr<Ipv4> ipv4);
private:
Ptr<Ipv4> m_ipv4;
std::map<Ipv4Address, Ptr<Ipv4Route>> m_routingTable;
// Additional methods for maintaining and updating routing table based on OSPF
void UpdateRoutingTable (void);
void FindShortestPaths (void);
};
} // namespace ns3
#endif // OSPF_ROUTING_PROTOCOL_H
ospf-routing-protocol.cc
#include “ospf-routing-protocol.h”
#include “ns3/log.h”
#include “ns3/simulator.h”
#include “ns3/ipv4-header.h”
#include “ns3/ipv4-route.h”
#include “ns3/inet-socket-address.h”
#include “ns3/inet6-socket-address.h”
#include “ns3/udp-socket-factory.h”
#include “ns3/uinteger.h”
namespace ns3 {
NS_LOG_COMPONENT_DEFINE (“OspfRoutingProtocol”);
NS_OBJECT_ENSURE_REGISTERED (OspfRoutingProtocol);
TypeId OspfRoutingProtocol::GetTypeId (void) {
static TypeId tid = TypeId (“ns3::OspfRoutingProtocol”)
.SetParent<Ipv4RoutingProtocol> ()
.SetGroupName (“Internet”)
.AddConstructor<OspfRoutingProtocol> ();
return tid;
}
OspfRoutingProtocol::OspfRoutingProtocol () {
NS_LOG_FUNCTION (this);
}
OspfRoutingProtocol::~OspfRoutingProtocol () {
NS_LOG_FUNCTION (this);
}
void OspfRoutingProtocol::DoDispose () {
NS_LOG_FUNCTION (this);
Ipv4RoutingProtocol::DoDispose ();
}
Ptr<Ipv4Route> OspfRoutingProtocol::RouteOutput (Ptr<Packet> p, const Ipv4Header &header, Ptr<NetDevice> oif, Socket::SocketErrno &sockerr) {
NS_LOG_FUNCTION (this << p << header << oif);
// Implement route output logic here
Ipv4Address dest = header.GetDestination();
auto it = m_routingTable.find(dest);
if (it != m_routingTable.end()) {
return it->second;
}
sockerr = Socket::ERROR_NOROUTETOHOST;
return Ptr<Ipv4Route> ();
}
bool OspfRoutingProtocol::RouteInput (Ptr<const Packet> p, const Ipv4Header &header,
Ptr<const NetDevice> idev, UnicastForwardCallback ucb,
MulticastForwardCallback mcb, LocalDeliverCallback lcb,
ErrorCallback ecb) {
NS_LOG_FUNCTION (this << p << header << idev);
// Implement route input logic here
Ipv4Address dest = header.GetDestination();
Ipv4Address local = m_ipv4->GetAddress(1, 0).GetLocal();
if (dest == local) {
lcb (p, header);
return true;
}
auto it = m_routingTable.find(dest);
if (it != m_routingTable.end()) {
ucb (it->second, p, header);
return true;
}
ecb (p, header, Socket::ERROR_NOROUTETOHOST);
return false;
}
void OspfRoutingProtocol::NotifyInterfaceUp (uint32_t interface) {
NS_LOG_FUNCTION (this << interface);
}
void OspfRoutingProtocol::NotifyInterfaceDown (uint32_t interface) {
NS_LOG_FUNCTION (this << interface);
}
void OspfRoutingProtocol::NotifyAddAddress (uint32_t interface, Ipv4InterfaceAddress address) {
NS_LOG_FUNCTION (this << interface << address);
}
void OspfRoutingProtocol::NotifyRemoveAddress (uint32_t interface, Ipv4InterfaceAddress address) {
NS_LOG_FUNCTION (this << interface << address);
}
void OspfRoutingProtocol::SetIpv4 (Ptr<Ipv4> ipv4) {
NS_LOG_FUNCTION (this << ipv4);
m_ipv4 = ipv4;
}
void OspfRoutingProtocol::UpdateRoutingTable (void) {
NS_LOG_FUNCTION (this);
// Implement logic to update the routing table based on OSPF
}
void OspfRoutingProtocol::FindShortestPaths (void) {
NS_LOG_FUNCTION (this);
// Implement logic to find the shortest paths using OSPF
}
} // namespace ns3
4. Create OSPF Helper and Forwarding Classes
Create helper and forwarding classes to facilitate the use and testing of OSPF.
ospf-helper.h
#ifndef OSPF_HELPER_H
#define OSPF_HELPER_H
#include “ns3/ipv4-routing-helper.h”
#include “ns3/ospf-routing-protocol.h”
#include “ns3/node-container.h”
namespace ns3 {
class OspfHelper : public Ipv4RoutingHelper {
public:
OspfHelper ();
virtual ~OspfHelper ();
OspfHelper* Copy (void) const;
virtual Ptr<Ipv4RoutingProtocol> Create (Ptr<Node> node) const;
private:
// Additional methods for OSPF functionality
};
} // namespace ns3
#endif // OSPF_HELPER_H
ospf-helper.cc
#include “ospf-helper.h”
#include “ns3/ipv4-list-routing.h”
#include “ns3/log.h”
namespace ns3 {
NS_LOG_COMPONENT_DEFINE (“OspfHelper”);
OspfHelper::OspfHelper () {
}
OspfHelper::~OspfHelper () {
}
OspfHelper* OspfHelper::Copy (void) const {
return new OspfHelper (*this);
}
Ptr<Ipv4RoutingProtocol> OspfHelper::Create (Ptr<Node> node) const {
Ptr<OspfRoutingProtocol> agent = CreateObject<OspfRoutingProtocol> ();
node->AggregateObject (agent);
return agent;
}
} // namespace ns3
5. Integrate OSPF with ns-3 Build System
Update the wscript file in the src directory to include your new OSPF module.
src/ospf/wscript
def build(bld):
module = bld.create_ns3_module(‘ospf’, [‘core’, ‘network’, ‘internet’])
module.source = [
‘model/ospf-routing-protocol.cc’,
‘helper/ospf-helper.cc’,
]
headers = bld(features=’ns3header’)
headers.module = ‘ospf’
headers.source = [
‘model/ospf-routing-protocol.h’,
‘helper/ospf-helper.h’,
]
- Build and Test
- Rebuild ns-3 to include your new OSPF module.
./waf configure
./waf build
- Create test scripts to verify the implementation of your OSPF protocol.
scratch/test-ospf.cc
#include “ns3/core-module.h”
#include “ns3/network-module.h”
#include “ns3/internet-module.h”
#include “ns3/ospf-helper.h”
#include “ns3/ipv4-static-routing-helper.h”
#include “ns3/ipv4-list-routing-helper.h”
using namespace ns3;
int main (int argc, char *argv[])
{
CommandLine cmd;
cmd.Parse (argc, argv);
NodeContainer nodes;
nodes.Create (4);
InternetStackHelper internet;
OspfHelper ospf;
Ipv4ListRoutingHelper list;
list.Add (ospf, 10);
internet.SetRoutingHelper (list);
internet.Install (nodes);
// Create point-to-point links
PointToPointHelper pointToPoint;
pointToPoint.SetDeviceAttribute (“DataRate”, StringValue (“5Mbps”));
pointToPoint.SetChannelAttribute (“Delay”, StringValue (“2ms”));
NetDeviceContainer devices;
devices = pointToPoint.Install (nodes.Get (0), nodes.Get (1));
devices.Add (pointToPoint.Install (nodes.Get (1), nodes.Get (2)));
devices.Add (pointToPoint.Install (nodes.Get (2), nodes.Get (3)));
// Assign IP addresses
Ipv4AddressHelper address;
address.SetBase (“10.1.1.0”, “255.255.255.0”);
Ipv4InterfaceContainer interfaces = address.Assign (devices);
// Add additional setup code for OSPF here
Simulator::Run ();
Simulator::Destroy ();
return 0;
}
7. Run and Debug
Run your test script and debug any issues that arise.
./waf –run scratch/test-ospf
Finally, we had implemented an OSPF in ns3 detailed manner. We provide related information about OSPF how it adjust and perform in different situation.
Carry on your programming related to OSPF in ns3 , where our developers gives you best outcomes.