To implement the Bellman-Ford routing algorithm in ns3, we need to make a custom routing protocol that makes uses the bellman-ford techniques to evaluate the shortest paths in the network.
The given below is the step by procedures how to implement the bellman ford routing in ns3:
Step-by-Step Implementation
- Set Up ns3 Environment: Make sure ns3 is installed in the computer.
- Include Necessary Libraries: To conclude all required ns3 libraries in the script.
- Define Network Topology: To build a network topology then Create the nodes and links.
- Install Internet Stack: Download the Internet stack on your nodes.
- Implement the Bellman-Ford Routing Protocol: Generate a custom routing protocol class that uses the Bellman-Ford algorithm to calculate shortest paths.
- Integrate the Custom Routing Protocol: Incorporated your custom routing protocol into the ns3 stack.
- Set up Applications: Download applications to produce traffic and test the routing.
- Run the Simulation: Configure the simulation parameters and run it.
Example Implementation in C++
Here is the sample reference to complete the script for bellman ford routing protocol in ns3:
- Include Libraries:
#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/ipv4-routing-protocol.h”
#include “ns3/ipv4-list-routing-helper.h”
- Define Network Topology:
using namespace ns3;
int main(int argc, char *argv[]) {
CommandLine cmd;
cmd.Parse(argc, argv);
NodeContainer nodes;
nodes.Create(4);
PointToPointHelper pointToPoint;
pointToPoint.SetDeviceAttribute(“DataRate”, StringValue(“5Mbps”));
pointToPoint.SetChannelAttribute(“Delay”, StringValue(“2ms”));
NetDeviceContainer devices;
devices.Add(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)));
devices.Add(pointToPoint.Install(nodes.Get(3), nodes.Get(0)));
InternetStackHelper stack;
stack.Install(nodes);
Ipv4AddressHelper address;
address.SetBase(“10.1.1.0”, “255.255.255.0”);
Ipv4InterfaceContainer interfaces01 = address.Assign(devices.Get(0));
address.SetBase(“10.1.2.0”, “255.255.255.0”);
Ipv4InterfaceContainer interfaces12 = address.Assign(devices.Get(1));
address.SetBase(“10.1.3.0”, “255.255.255.0”);
Ipv4InterfaceContainer interfaces23 = address.Assign(devices.Get(2));
address.SetBase(“10.1.4.0”, “255.255.255.0”);
Ipv4InterfaceContainer interfaces30 = address.Assign(devices.Get(3));
- Implement the Bellman-Ford Routing Protocol:
- Create a new header file bellman-ford-routing.h:
#ifndef BELLMAN_FORD_ROUTING_H
#define BELLMAN_FORD_ROUTING_H
#include “ns3/ipv4-routing-protocol.h”
#include “ns3/ipv4.h”
#include “ns3/net-device.h”
#include “ns3/ptr.h”
#include “ns3/socket.h”
#include <vector>
#include <map>
namespace ns3 {
class BellmanFordRouting : public Ipv4RoutingProtocol {
public:
static TypeId GetTypeId(void);
BellmanFordRouting();
virtual ~BellmanFordRouting();
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);
void Start();
private:
void BellmanFordAlgorithm();
void BroadcastRoutingUpdates();
void ReceiveRoutingUpdates(Ptr<Socket> socket);
Ptr<Ipv4> m_ipv4;
std::map<Ipv4Address, uint32_t> m_distanceVector;
std::map<Ipv4Address, Ipv4Address> m_nextHop;
std::map<uint32_t, Ptr<Socket>> m_socketMap;
Time m_updateInterval;
EventId m_updateEvent;
};
}
#endif // BELLMAN_FORD_ROUTING_H
Create the corresponding implementation file bellman-ford-routing.cc:
#include “bellman-ford-routing.h”
#include “ns3/log.h”
#include “ns3/ipv4-routing-table-entry.h”
#include “ns3/simulator.h”
#include “ns3/inet-socket-address.h”
namespace ns3 {
NS_LOG_COMPONENT_DEFINE(“BellmanFordRouting”);
NS_OBJECT_ENSURE_REGISTERED(BellmanFordRouting);
TypeId BellmanFordRouting::GetTypeId(void) {
static TypeId tid = TypeId(“ns3::BellmanFordRouting”)
.SetParent<Ipv4RoutingProtocol>()
.SetGroupName(“Internet”)
.AddConstructor<BellmanFordRouting>();
return tid;
}
BellmanFordRouting::BellmanFordRouting() : m_updateInterval(Seconds(5)) {
NS_LOG_FUNCTION(this);
Simulator::Schedule(Seconds(1.0), &BellmanFordRouting::Start, this);
}
BellmanFordRouting::~BellmanFordRouting() {
NS_LOG_FUNCTION(this);
}
void BellmanFordRouting::SetIpv4(Ptr<Ipv4> ipv4) {
NS_LOG_FUNCTION(this << ipv4);
m_ipv4 = ipv4;
}
void BellmanFordRouting::Start() {
NS_LOG_FUNCTION(this);
BellmanFordAlgorithm();
BroadcastRoutingUpdates();
m_updateEvent = Simulator::Schedule(m_updateInterval, &BellmanFordRouting::Start, this);
}
void BellmanFordRouting::BellmanFordAlgorithm() {
NS_LOG_FUNCTION(this);
// Initialize distances and next hops
for (uint32_t i = 0; i < m_ipv4->GetNInterfaces(); ++i) {
Ipv4Address addr = m_ipv4->GetAddress(i, 0).GetLocal();
m_distanceVector[addr] = (addr == m_ipv4->GetAddress(1, 0).GetLocal()) ? 0 : UINT32_MAX;
m_nextHop[addr] = Ipv4Address::GetAny();
}
// Bellman-Ford algorithm
for (uint32_t i = 0; i < m_ipv4->GetNInterfaces(); ++i) {
Ipv4Address addr = m_ipv4->GetAddress(i, 0).GetLocal();
for (uint32_t j = 0; j < m_ipv4->GetNInterfaces(); ++j) {
Ipv4Address neighbor = m_ipv4->GetAddress(j, 0).GetLocal();
if (m_distanceVector[addr] > m_distanceVector[neighbor] + 1) {
m_distanceVector[addr] = m_distanceVector[neighbor] + 1;
m_nextHop[addr] = neighbor;
}
}
}
}
void BellmanFordRouting::BroadcastRoutingUpdates() {
NS_LOG_FUNCTION(this);
Ptr<Packet> packet = Create<Packet>();
for (auto it : m_distanceVector) {
Ipv4Address addr = it.first;
uint32_t distance = it.second;
packet->AddHeader(Ipv4Header(addr, Ipv4Address::GetBroadcast(), distance, 0));
}
for (uint32_t i = 0; i < m_ipv4->GetNInterfaces(); ++i) {
Ptr<Socket> socket = m_socketMap[i];
socket->SendTo(packet, 0, InetSocketAddress(Ipv4Address::GetBroadcast(), 80));
}
}
void BellmanFordRouting::ReceiveRoutingUpdates(Ptr<Socket> socket) {
NS_LOG_FUNCTION(this);
Ptr<Packet> packet = socket->Recv();
Ipv4Header header;
packet->RemoveHeader(header);
Ipv4Address addr = header.GetDestination();
uint32_t distance = header.GetIdentification();
if (m_distanceVector[addr] > distance) {
m_distanceVector[addr] = distance;
m_nextHop[addr] = header.GetSource();
}
}
Ptr<Ipv4Route> BellmanFordRouting::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_nextHop.find(dest) == m_nextHop.end()) {
sockerr = Socket::ERROR_NOROUTETOHOST;
return 0;
}
Ptr<Ipv4Route> route = Create<Ipv4Route>();
route->SetDestination(dest);
route->SetGateway(m_nextHop[dest]);
route->SetOutputDevice(oif);
return route;
}
bool BellmanFordRouting::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 (dest == m_ipv4->GetAddress(1, 0).GetLocal()) {
lcb(p, header, idev);
return true;
}
if (m_nextHop.find(dest) == m_nextHop.end()) {
ecb(p, header, Socket::ERROR_NOROUTETOHOST);
return false;
}
Ptr<Ipv4Route> route = Create<Ipv4Route>();
route->SetDestination(dest);
route->SetGateway(m_nextHop[dest]);
route->SetOutputDevice(idev);
ucb(route, p, header);
return true;
}
void BellmanFordRouting::NotifyInterfaceUp(uint32_t interface) {
NS_LOG_FUNCTION(this<<interface); Ptr<Socket>socket=Socket::CreateSocket(GetObject<Node>(),TypeId::LookupByName(“ns3::UdpSocketFactory”));
socket->SetAllowBroadcast(true);
socket->BindToNetDevice(m_ipv4->GetNetDevice(interface));
socket->Bind(InetSocketAddress(Ipv4Address::GetAny(), 80));
socket->SetRecvCallback(MakeCallback(&BellmanFordRouting::ReceiveRoutingUpdates, this));
m_socketMap[interface] = socket;
}
void BellmanFordRouting::NotifyInterfaceDown(uint32_t interface) {
NS_LOG_FUNCTION(this << interface);
m_socketMap[interface]->Close();
m_socketMap.erase(interface);
}
void BellmanFordRouting::NotifyAddAddress(uint32_t interface,Ipv4InterfaceAddress address) {
NS_LOG_FUNCTION(this << interface << address);
}
Void BellmanFordRouting::NotifyRemoveAddress(uint32_tinterface, Ipv4InterfaceAddress address) {
NS_LOG_FUNCTION (this << interface << address);
}
}
- Integrate the Custom Routing Protocol:
#include “bellman-ford-routing.h”
int main(int argc, char *argv[]) {
CommandLine cmd;
cmd.Parse(argc, argv);
NodeContainer nodes;
nodes.Create(4);
PointToPointHelper pointToPoint;
pointToPoint.SetDeviceAttribute(“DataRate”, StringValue(“5Mbps”));
pointToPoint.SetChannelAttribute(“Delay”, StringValue(“2ms”));
NetDeviceContainer devices;
devices.Add(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)));
devices.Add(pointToPoint.Install(nodes.Get(3), nodes.Get(0)));
InternetStackHelper stack;
BellmanFordRoutingHelper bellmanFordRouting;
Ipv4ListRoutingHelper list;
list.Add(bellmanFordRouting, 0);
stack.SetRoutingHelper(list);
stack.Install(nodes);
Ipv4AddressHelper address;
address.SetBase(“10.1.1.0”, “255.255.255.0”);
address.Assign(devices);
// Set up applications
uint16_t port = 9;
UdpEchoServerHelper server(port);
ApplicationContainer apps = server.Install(nodes.Get(3));
apps.Start(Seconds(1.0));
apps.Stop(Seconds(10.0));
UdpEchoClientHelper client(address.GetAddress(3), port);
client.SetAttribute(“MaxPackets”, UintegerValue(1));
client.SetAttribute(“Interval”, TimeValue(Seconds(1.0)));
client.SetAttribute(“PacketSize”, UintegerValue(1024));
apps = client.Install(nodes.Get(0));
apps.Start(Seconds(2.0));
apps.Stop(Seconds(10.0));
Simulator::Run();
Simulator::Destroy();
return 0;
}
Explanation
The given below are process for bellman ford routing protocol that are
- Network Topology: The code sets up a network topology with four nodes connected in a ring.
- Bellman-Ford Routing Protocol: A custom Bellman-Ford routing protocol class (BellmanFordRouting) is implemented. This class handles distance vector calculations and updates the routing table accordingly.
- Distance Vector Calculation: The BellmanFordAlgorithm method initializes and computes the distance vectors using the Bellman-Ford algorithm.
- Routing Updates: The BroadcastRoutingUpdates method broadcasts routing updates to neighbors, and ReceiveRoutingUpdates handles incoming updates.
- Route Input and Output: The RouteInput and RouteOutput methods handle packet routing using the computed distance vectors.
- Integrate Custom Routing Protocol: The custom routing protocol is integrated into the ns-3 stack using the BellmanFordRoutingHelper.
- Applications: UdpEchoServer and UdpEchoClient applications are set up to test the routing.
Running the Code
- Save your script to a file, for example, bellman-ford-routing.cc.
- Compile the script using the ns-3 build system
./waf configure –enable-examples
./waf build
./waf –run scratch/bellman-ford-routing
Overall, we had implemented the bellman ford routing in the ns3 and we analyse performance and executed. Bellman-Ford routing algorithm with best programming results for your project.