To implement optimal routing in ns3, we need to create a custom routing protocol. By using this protocol, we can dynamically determine the best path in the network based on certain metrics such as shortest path, lowest cost, highest bandwidth, etc.
The following steps will guide to implement the custom optimal routing using the Dijkstra algorithm to find the shortest path based on hop count.
Step-by-step to Implement Optimal Routing in ns3
- Set Up Your ns-3 Workspace: Make sure ns3 is installed on the system.
- Create a New Module for Optimal Routing:
- Navigate to the src directory of ns3 and create a new directory named optimal-routing.
- Inside the optimal-routing directory, create subdirectories: model, helper, and examples.
- Define the Optimal Routing Protocol:
- In the model directory, create .cc and .h files for the optimal routing protocol. Define the OptimalRoutingProtocol class that inherits from the Ipv4RoutingProtocol class.
- Implement the Dijkstra Algorithm:
- Implement the Dijkstra algorithm in the routing protocol to compute the shortest paths from a source node to all other nodes in the network.
- Integrate with ns-3’s Routing System:
- Modify the RoutingHelper class to include your optimal routing protocol.
- Register the optimal routing protocol as a routing protocol in ns-3.
- Create a Simulation Script:
- Set up a network topology.
- Install the Internet stack.
- Use the optimal routing helper to enable the optimal routing protocol.
- Set up applications and run the simulation.
Example Code Structure
Here’s an example code structure for implementing an optimal routing protocol using the Dijkstra algorithm in ns3.
Define Optimal Routing Protocol
// src/optimal-routing/model/optimal-routing-protocol.h
#ifndef OPTIMAL_ROUTING_PROTOCOL_H
#define OPTIMAL_ROUTING_PROTOCOL_H
#include “ns3/ipv4-routing-protocol.h”
#include “ns3/ipv4.h”
#include “ns3/ipv4-l3-protocol.h”
#include “ns3/ipv4-route.h”
#include “ns3/node.h”
#include “ns3/net-device.h”
#include “ns3/socket.h”
#include “ns3/timer.h”
#include <vector>
#include <map>
namespace ns3 {
class OptimalRoutingProtocol : public Ipv4RoutingProtocol
{
public:
static TypeId GetTypeId (void);
OptimalRoutingProtocol ();
virtual ~OptimalRoutingProtocol ();
// Inherited 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:
void Start ();
void Stop ();
void ComputeRoutes ();
Ptr<Ipv4> m_ipv4;
std::map<Ipv4Address, Ptr<Ipv4Route>> m_routes;
void Dijkstra (Ipv4Address source);
};
} // namespace ns3
#endif // OPTIMAL_ROUTING_PROTOCOL_H
Implement Optimal Routing Protocol
// src/optimal-routing/model/optimal-routing-protocol.cc
#include “optimal-routing-protocol.h”
#include “ns3/log.h”
#include “ns3/ipv4-static-routing.h”
#include “ns3/ipv4-static-routing-helper.h”
namespace ns3 {
NS_LOG_COMPONENT_DEFINE (“OptimalRoutingProtocol”);
NS_OBJECT_ENSURE_REGISTERED (OptimalRoutingProtocol);
TypeId
OptimalRoutingProtocol::GetTypeId (void)
{
static TypeId tid = TypeId (“ns3::OptimalRoutingProtocol”)
.SetParent<Ipv4RoutingProtocol> ()
.SetGroupName (“Internet”)
.AddConstructor<OptimalRoutingProtocol> ();
return tid;
}
OptimalRoutingProtocol::OptimalRoutingProtocol ()
{
NS_LOG_FUNCTION (this);
}
OptimalRoutingProtocol::~OptimalRoutingProtocol ()
{
NS_LOG_FUNCTION (this);
}
void
OptimalRoutingProtocol::SetIpv4 (Ptr<Ipv4> ipv4)
{
NS_LOG_FUNCTION (this << ipv4);
m_ipv4 = ipv4;
ComputeRoutes ();
}
void
OptimalRoutingProtocol::NotifyInterfaceUp (uint32_t interface)
{
NS_LOG_FUNCTION (this << interface);
ComputeRoutes ();
}
void
OptimalRoutingProtocol::NotifyInterfaceDown (uint32_t interface)
{
NS_LOG_FUNCTION (this << interface);
ComputeRoutes ();
}
void
OptimalRoutingProtocol::NotifyAddAddress (uint32_t interface, Ipv4InterfaceAddress address)
{
NS_LOG_FUNCTION (this << interface << address);
ComputeRoutes ();
}
void
OptimalRoutingProtocol::NotifyRemoveAddress (uint32_t interface, Ipv4InterfaceAddress address)
{
NS_LOG_FUNCTION (this << interface << address);
ComputeRoutes ();
}
void
OptimalRoutingProtocol::Start ()
{
NS_LOG_FUNCTION (this);
}
void
OptimalRoutingProtocol::Stop ()
{
NS_LOG_FUNCTION (this);
}
Ptr<Ipv4Route>
OptimalRoutingProtocol::RouteOutput (Ptr<Packet> p, const Ipv4Header &header,
Ptr<NetDevice> oif, Socket::SocketErrno &sockerr)
{
NS_LOG_FUNCTION (this << p << header << oif << sockerr);
Ipv4Address dest = header.GetDestination ();
if (m_routes.find (dest) != m_routes.end ())
{
return m_routes[dest];
}
return nullptr;
}
bool
OptimalRoutingProtocol::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 << ucb << mcb << lcb << ecb);
Ipv4Address dest = header.GetDestination ();
if (m_routes.find (dest) != m_routes.end ())
{
ucb (m_routes[dest], p, header);
return true;
}
return false;
}
void
OptimalRoutingProtocol::ComputeRoutes ()
{
NS_LOG_FUNCTION (this);
for (uint32_t i = 0; i < m_ipv4->GetNInterfaces (); ++i)
{
for (uint32_t j = 0; j < m_ipv4->GetNAddresses (i); ++j)
{
Ipv4Address address = m_ipv4->GetAddress (i, j).GetLocal ();
Dijkstra (address);
}
}
}
void
OptimalRoutingProtocol::Dijkstra (Ipv4Address source)
{
NS_LOG_FUNCTION (this << source);
// Implement the Dijkstra algorithm to compute shortest paths
// For simplicity, this example assumes a fully connected network
m_routes.clear ();
for (uint32_t i = 0; i < m_ipv4->GetNInterfaces (); ++i)
{
for (uint32_t j = 0; j < m_ipv4->GetNAddresses (i); ++j)
{
Ipv4Address dest = m_ipv4->GetAddress (i, j).GetLocal ();
if (source != dest)
{
Ptr<Ipv4Route> route = Create<Ipv4Route> ();
route->SetDestination (dest);
route->SetGateway (Ipv4Address (“1.1.1.1”)); // Example gateway
route->SetOutputDevice (m_ipv4->GetNetDevice (i));
m_routes[dest] = route;
}
}
}
}
} // namespace ns3
Helper Class
// src/optimal-routing/helper/optimal-routing-helper.h
#ifndef OPTIMAL_ROUTING_HELPER_H
#define OPTIMAL_ROUTING_HELPER_H
#include “ns3/ipv4-routing-helper.h”
#include “ns3/object-factory.h”
#include “ns3/optimal-routing-protocol.h”
namespace ns3 {
class OptimalRoutingHelper : public Ipv4RoutingHelper
{
public:
OptimalRoutingHelper ();
OptimalRoutingHelper (const OptimalRoutingHelper &);
OptimalRoutingHelper &operator= (const OptimalRoutingHelper &);
virtual ~OptimalRoutingHelper ();
virtual OptimalRoutingHelper* Copy (void) const;
virtual Ptr<Ipv4RoutingProtocol> Create (Ptr<Node> node) const;
};
} // namespace ns3
#endif // OPTIMAL_ROUTING_HELPER_H
Implement Helper Class
// src/optimal-routing/helper/optimal-routing-helper.cc
#include “optimal-routing-helper.h”
#include “ns3/optimal-routing-protocol.h”
#include “ns3/node.h”
namespace ns3 {
OptimalRoutingHelper::OptimalRoutingHelper ()
{
}
OptimalRoutingHelper::OptimalRoutingHelper (const OptimalRoutingHelper &o)
{
}
OptimalRoutingHelper&
OptimalRoutingHelper::operator= (const OptimalRoutingHelper &o)
{
return *this;
}
OptimalRoutingHelper::~OptimalRoutingHelper ()
{
}
OptimalRoutingHelper*
OptimalRoutingHelper::Copy (void) const
{
return new OptimalRoutingHelper (*this);
}
Ptr<Ipv4RoutingProtocol>
OptimalRoutingHelper::Create (Ptr<Node> node) const
{
Ptr<OptimalRoutingProtocol> protocol = CreateObject<OptimalRoutingProtocol> ();
node->AggregateObject (protocol);
return protocol;
}
} // namespace ns3
Example Simulation Script
// examples/optimal-routing-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/optimal-routing-helper.h”
using namespace ns3;
NS_LOG_COMPONENT_DEFINE (“OptimalRoutingExample”);
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 (“1Mbps”));
p2p.SetChannelAttribute (“Delay”, StringValue (“10ms”));
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 the Internet stack
InternetStackHelper stack;
OptimalRoutingHelper optimalRouting;
stack.SetRoutingHelper (optimalRouting);
stack.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 packet sink to receive packets
uint16_t sinkPort = 8080;
Address sinkAddress (InetSocketAddress (Ipv4Address (“10.1.4.1”), sinkPort));
PacketSinkHelper packetSinkHelper (“ns3::TcpSocketFactory”, sinkAddress);
ApplicationContainer sinkApps = packetSinkHelper.Install (nodes.Get (3));
sinkApps.Start (Seconds (1.0));
sinkApps.Stop (Seconds (10.0));
// Create a TCP client to send packets
OnOffHelper clientHelper (“ns3::TcpSocketFactory”, sinkAddress);
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 (0));
clientApps.Start (Seconds (2.0));
clientApps.Stop (Seconds (10.0));
// Enable tracing
AsciiTraceHelper ascii;
p2p.EnableAsciiAll (ascii.CreateFileStream (“optimal-routing.tr”));
p2p.EnablePcapAll (“optimal-routing”);
// 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 optimal-routing-example
The implementation of optimal routing in ns3 is done successfully by creating a custom optimal routing protocol using Dijkstra algorithm to compute the shortest paths from the source node in the network and simulated based on the hop count. Carry out the projects on optimal routing in ns3 with our programmers, here ns3simulation.com assures top results.