To implement Flow-based routing in ns3, it requires routing decisions on the basis of characteristics of the traffic flows, like source and destination addresses, port numbers, or other criteria.
Here are the steps to implement a basic flow-based routing protocol in ns3.
Steps for implementation
- Set up your ns3 :
- Make sure that ns3 is installed in the computer. If not, install it.
- Include necessary libraries :
- In your script, include the necessary libraries.
- Define network topology :
- For your network topology, create the nodes and links.
- Install Internet Stack :
- On your nodes, install the internet stack.
- Implement the flow based routing protocol :
- Create a custom routing protocol class to route packets based on flow characteristics.
- Integrate the Custom Routing Protocol :
- On the ns3 stack, integrate your custom routing protocol.
- Set Up Applications :
- To generate traffic and test the routing, install applications.
- Run the Simulation :
- Define the simulation parameters and run it.
Example implementation in C++
Here is a complete example on implementing a basic flow based 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”
#include “ns3/ipv4-static-routing-helper.h”
#include <map>
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 devices01 = pointToPoint.Install(nodes.Get(0), nodes.Get(1));
NetDeviceContainer devices12 = pointToPoint.Install(nodes.Get(1), nodes.Get(2));
NetDeviceContainer devices23 = pointToPoint.Install(nodes.Get(2), nodes.Get(3));
NetDeviceContainer devices30 = 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(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);
Implement the Flow-Based Routing Protocol :
- Create a new header file flow-based-routing.h:
#ifndef FLOW_BASED_ROUTING_H
#define FLOW_BASED_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 <map>
namespace ns3 {
class FlowBasedRouting : public Ipv4RoutingProtocol {
public:
static TypeId GetTypeId(void);
FlowBasedRouting();
virtual ~FlowBasedRouting();
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 ComputeRoutes();
void DistributeRoutes();
void ReceiveRoutes(Ptr<Socket> socket);
Ptr<Ipv4> m_ipv4;
std::map<std::pair<Ipv4Address, uint16_t>, Ipv4Address> m_routingTable; // Flow-based routing table
std::map<uint32_t, Ptr<Socket>> m_socketMap;
Time m_updateInterval;
EventId m_updateEvent;
};
}
#endif // FLOW_BASED_ROUTING_H
Create the corresponding implementation file flow-based-routing.cc:
#include “flow-based-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(“FlowBasedRouting”);
NS_OBJECT_ENSURE_REGISTERED(FlowBasedRouting);
TypeId FlowBasedRouting::GetTypeId(void) {
static TypeId tid = TypeId(“ns3::FlowBasedRouting”)
.SetParent<Ipv4RoutingProtocol>()
.SetGroupName(“Internet”)
.AddConstructor<FlowBasedRouting>();
return tid;
}
FlowBasedRouting::FlowBasedRouting() : m_updateInterval(Seconds(5)) {
NS_LOG_FUNCTION(this);
Simulator::Schedule(Seconds(1.0), &FlowBasedRouting::Start, this);
}
FlowBasedRouting::~FlowBasedRouting() {
NS_LOG_FUNCTION(this);
}
void FlowBasedRouting::SetIpv4(Ptr<Ipv4> ipv4) {
NS_LOG_FUNCTION(this << ipv4);
m_ipv4 = ipv4;
}
void FlowBasedRouting::Start() {
NS_LOG_FUNCTION(this);
ComputeRoutes();
DistributeRoutes();
m_updateEvent = Simulator::Schedule(m_updateInterval, &FlowBasedRouting::Start, this);
}
void FlowBasedRouting::ComputeRoutes() {
NS_LOG_FUNCTION(this);
// Example route computation: assign routes based on flows (source, destination, and port)
// Here we can add any custom logic for route computation based on flows
m_routingTable[std::make_pair(Ipv4Address(“10.1.1.1”), 9)] = Ipv4Address(“10.1.2.1”);
m_routingTable[std::make_pair(Ipv4Address(“10.1.2.1”), 9)] = Ipv4Address(“10.1.3.1”);
m_routingTable[std::make_pair(Ipv4Address(“10.1.3.1”), 9)] = Ipv4Address(“10.1.4.1”);
}
void FlowBasedRouting::DistributeRoutes() {
NS_LOG_FUNCTION(this);
Ptr<Packet> packet = Create<Packet>();
for (auto const &entry : m_routingTable) {
Ipv4Header header;
header.SetSource(entry.first.first);
header.SetDestination(entry.second);
packet->AddHeader(header);
}
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 FlowBasedRouting::ReceiveRoutes(Ptr<Socket> socket) {
NS_LOG_FUNCTION(this);
Ptr<Packet> packet = socket->Recv();
Ipv4Header header;
packet->RemoveHeader(header);
Ipv4Address src = header.GetSource();
Ipv4Address dest = header.GetDestination();
m_routingTable[std::make_pair(src, header.GetIdentification())] = dest;
}
Ptr<Ipv4Route> FlowBasedRouting::RouteOutput(
Ptr<Packet> p, const Ipv4Header &header, Ptr<NetDevice> oif,
Socket::SocketErrno &sockerr) {
NS_LOG_FUNCTION(this << p << header << oif << sockerr);
auto flowKey = std::make_pair(header.GetSource(), header.GetIdentification());
if (m_routingTable.find(flowKey) == m_routingTable.end()) {
sockerr = Socket::ERROR_NOROUTETOHOST;
return 0;
}
Ptr<Ipv4Route> route = Create<Ipv4Route>();
route->SetDestination(header.GetDestination());
route->SetGateway(m_routingTable[flowKey]);
route->SetOutputDevice(oif);
return route;
}
bool FlowBasedRouting::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);
auto flowKey = std::make_pair(header.GetSource(), header.GetIdentification());
if (m_routingTable.find(flowKey) == m_routingTable.end()) {
ecb(p, header, Socket::ERROR_NOROUTETOHOST);
return false;
}
Ptr<Ipv4Route> route = Create<Ipv4Route>();
route->SetDestination(header.GetDestination());
route->SetGateway(m_routingTable[flowKey]);
route->SetOutputDevice(idev);
ucb(route, p, header);
return true;
}
void FlowBasedRouting::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(&FlowBasedRouting::ReceiveRoutes, this));
m_socketMap[interface] = socket;
}
void FlowBasedRouting::NotifyInterfaceDown(uint32_t interface) {
NS_LOG_FUNCTION(this << interface);
m_socketMap[interface]->Close();
m_socketMap.erase(interface);
}
void FlowBasedRouting::NotifyAddAddress(uint32_t interface,
Ipv4InterfaceAddress address) {
NS_LOG_FUNCTION(this << interface << address);
}
void FlowBasedRouting::NotifyRemoveAddress(uint32_t interface,
Ipv4InterfaceAddress address) {
NS_LOG_FUNCTION(this << interface << address);
}
}
Integrate the Custom Routing Protocol:
#include “flow-based-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 devices01 = pointToPoint.Install(nodes.Get(0), nodes.Get(1));
NetDeviceContainer devices12 = pointToPoint.Install(nodes.Get(1), nodes.Get(2));
NetDeviceContainer devices23 = pointToPoint.Install(nodes.Get(2), nodes.Get(3));
NetDeviceContainer devices30 = pointToPoint.Install(nodes.Get(3), nodes.Get(0));
InternetStackHelper stack;
FlowBasedRoutingHelper flowBasedRouting;
Ipv4ListRoutingHelper list;
list.Add(flowBasedRouting, 0);
stack.SetRoutingHelper(list);
stack.Install(nodes);
Ipv4AddressHelper address;
address.SetBase(“10.1.1.0”, “255.255.255.0”);
address.Assign(devices01);
address.SetBase(“10.1.2.0”, “255.255.255.0”);
address.Assign(devices12);
address.SetBase(“10.1.3.0”, “255.255.255.0”);
address.Assign(devices23);
address.SetBase(“10.1.4.0”, “255.255.255.0”);
address.Assign(devices30);
// 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
- Network Topology :
The four nodes connected in a ring, to set up the network topology.
- Flow based routing protocol :
A custom flow based routing protocol is implemented for handling route computation and distribution based on flow based principles.
- Route Computation :
The ComputeRoutes method computes routes for specific flows, identified by source address and port number.
- Route distribution :
The DistributeRoutes method broadcasts the computed routes to all nodes in the network.
- Route Input and Output :
To handle packet routing based on the routing table, the RouteInput and RouteOutput methods are used.
- Integrate Custom Routing Protocol :
The custom routing protocol is integrated into the ns3 stack using the flowbased RoutingHelper.
- Applications :
To set up to test the routing, UdpEchoServer and UdpEchoClient applications are used.
Running the Code :
Save your script to a file, for example, flow-based-routing.cc and Compile the script using the ns3 build system
./waf configure –enable-examples
./waf build
./waf –run scratch/flow-based-routing
Overall, we had successfully learned on implementing Flow based routing in ns3 which involves routing decisions based on the characteristics of the traffic flows, such as source and destination addresses, port numbers and other criteria.
Implementing flow-based routing in ns3 can be quite challenging, but you can overcome all your research obstacles with the assistance of our top developers.