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How to Implement flow based routing in OMNeT++

To implement the Flow-based routing is a technique where routing decisions are prepared based on the descriptions of flows like IP flows instead of individual packets. It can be helpful for optimizing network resources, managing QoS, or executing security policies. Implementing flow-based routing in OMNeT++ needs to creating a routing module that can recognize and handle different flows, and route packets based on flow features.

Here, we see how to implement flow-based routing in OMNeT++ using the INET framework.

Step-by-Step Implementations:

Step 1: Set Up OMNeT++ and INET Framework

  1. Install OMNeT++:
    • Make sure OMNeT++ is installed on the system. You can download it from the OMNeT++
  2. Install the INET Framework:
    • Download and install the INET Framework, which offers different networking protocols and models. INET can be downloaded from the INET GitHub repository.

Step 2: Create a New OMNeT++ Project

  1. Create the Project:
    • Open OMNeT++ and make a new OMNeT++ project through File > New > OMNeT++ Project.
    • Name the project like FlowBasedRoutingSimulation and set up the project directory.
  2. Set Up Project Dependencies:
    • Make certain the project references the INET Framework by right-clicking on the project in the Project Explorer, moving to Properties > Project References, and ensuring the INET project.

Step 3: Define the Network Topology

  1. Create a NED File:
    • Define the network topology using the NED language. This topology will contains routers, hosts, and possibly a controller for managing flow-based routing decisions.

Example:

network FlowBasedRoutingNetwork

{

submodules:

router1: Router;

router2: Router;

router3: Router;

router4: Router;

host1: StandardHost;

host2: StandardHost;

connections allowunconnected:

router1.ethg++ <–> Eth10Mbps <–> router2.ethg++;

router2.ethg++ <–> Eth10Mbps <–> router3.ethg++;

router3.ethg++ <–> Eth10Mbps <–> router4.ethg++;

router1.ethg++ <–> Eth10Mbps <–> host1.ethg++;

router4.ethg++ <–> Eth10Mbps <–> host2.ethg++;

}

  1. Configure Network Parameters:
    • Set up necessary link parameters like bandwidth, delay, and packet loss to mimic a realistic network setting.

Step 4: Implement Flow-Based Routing Module

  1. Define the Flow-Based Routing Module:
    • To form a new module in NED for the flow-based routing protocol. Flow based routing module will find flows and make routing decisions based on flow characteristics.

Example (in NED):

simple FlowBasedRouting

{

parameters:

@display(“i=block/network2”);

gates:

inout lowerLayerIn[];

inout lowerLayerOut[];

}

  1. Implement Flow-Based Routing Logic in C++:
    • Implement the routing logic in C++ that discovers various flows like based on source/destination IP and port and routes packets based on these flows.

Example (C++ implementation):

#include <map>

#include “inet/common/INETDefs.h”

#include “inet/networklayer/contract/IRoutingTable.h”

#include “inet/networklayer/ipv4/IPv4RoutingTable.h”

#include “inet/transportlayer/contract/udp/UDPPacket.h”

#include “inet/transportlayer/contract/tcp/TCPConnection.h”

class FlowBasedRouting : public cSimpleModule

{

private:

struct FlowEntry {

std::string nextHop;

double priority;  // Could be used for QoS or load balancing

};

std::map<std::string, FlowEntry> flowTable;  // Flow ID -> FlowEntry

IRoutingTable *inetRoutingTable;

protected:

virtual void initialize() override;

virtual void handleMessage(cMessage *msg) override;

std::string identifyFlow(cPacket *packet);

void setupFlowTable();

};

Define_Module(FlowBasedRouting);

void FlowBasedRouting::initialize() {

inetRoutingTable = getModuleFromPar<IRoutingTable>(par(“routingTableModule”), this);

 

// Initialize the flow table with some example data

setupFlowTable();

}

void FlowBasedRouting::handleMessage(cMessage *msg) {

cPacket *packet = check_and_cast<cPacket *>(msg);

std::string flowID = identifyFlow(packet);

if (flowTable.find(flowID) != flowTable.end()) {

std::string nextHop = flowTable[flowID].nextHop;

EV << “Routing flow ” << flowID << ” via ” << nextHop << endl;

// Forward the packet based on the next hop in the flow table

send(packet, “lowerLayerOut”, inetRoutingTable->getInterfaceByAddress(Ipv4Address(nextHop.c_str()))->getNetworkLayerGateIndex());

} else {

// Handle packets with no specific flow entry (e.g., drop or use default route)

EV << “Flow ” << flowID << ” not found, using default route.” << endl;

// Handle default routing here

}

}

std::string FlowBasedRouting::identifyFlow(cPacket *packet) {

// Identify the flow based on packet characteristics (e.g., IP src/dst, port numbers)

if (auto *udpPacket = dynamic_cast<inet::UDPPacket *>(packet)) {

return udpPacket->getSourceAddress().str() + “-” + udpPacket->getDestinationAddress().str() + “:” + std::to_string(udpPacket->getSourcePort()) + “-” + std::to_string(udpPacket->getDestinationPort());

} else if (auto *tcpPacket = dynamic_cast<inet::TCPConnection *>(packet)) {

return tcpPacket->getLocalAddress().str() + “-” + tcpPacket->getRemoteAddress().str() + “:” + std::to_string(tcpPacket->getLocalPort()) + “-” + std::to_string(tcpPacket->getRemotePort());

}

// Fallback for other types of packets

return packet->getFullName();

}

void FlowBasedRouting::setupFlowTable() {

// Example: Setting up static flow entries

flowTable[“10.0.0.1-10.0.0.2:1234-80”] = {“router2”, 1.0};  // Example flow from 10.0.0.1:1234 to 10.0.0.2:80 routed via router2

flowTable[“10.0.0.1-10.0.0.3:1234-443”] = {“router3”, 2.0};  // Example flow from 10.0.0.1:1234 to 10.0.0.3:443 routed via router3

}

    • Flow Identification: The identifyFlow function produces a flow identifier based on packet characteristics like IP addresses and port numbers.
    • Flow Table: The flow table maps flow identifiers to routing decisions such as next hop, priority.
    • Routing Logic: Packets are routed based on their flow identifier, using the flow table to determine the suitable next hop.

Step 5: Set Up the Simulation

  1. Configure the Simulation in omnetpp.ini:
  • Set up the simulation parameters, like traffic patterns, network settings, and simulation time.

Example:

[General]

network = FlowBasedRoutingNetwork

sim-time-limit = 100s

**.scalar-recording = true

**.vector-recording = true

# Application traffic configuration

*.host1.numApps = 1

*.host1.app[0].typename = “UdpBasicApp”

*.host1.app[0].destAddress = “host2”

*.host1.app[0].destPort = 80

*.host1.app[0].messageLength = 1024B

*.host1.app[0].sendInterval = uniform(1s, 2s)

  1. Traffic Configuration:
    • Set up application-level traffic between hosts to make network activity, triggering the flow-based routing protocol.

Step 6: Run the Simulation

  1. Compile the Project:
    • Make sure everything is properly implemented and compiled.
  2. Run Simulations:
    • Perform the simulations using OMNeT++’s IDE or command line. Monitor how the flow-based routing protocol performs under numerous conditions.

Step 7: Analyze the Results

  1. Monitor Flow-Based Routing Behavior:
    • Estimate how the flow-based routing protocol handles routing, specifically how it manages various flows and balances traffic.
  2. Evaluate Performance:
    • Evaluate key performance metrics like packet delivery ratio, end-to-end delay, and routing overhead.
    • Scalars and Vectors: Use OMNeT++ tools to record and analyse scalar and vector data, like the number of packets sent, received, and dropped, in addition to the time taken to deliver packets.
  3. Check for Issues:
    • Consider for issues like routing loops, packet loss, or excessive delay that may indicate difficulties with the flow-based routing logic.

Step 8: Refine and Optimize the Protocol

  1. Address Any Issues:
    • Enhance the routing logic based on the simulation results to elevate performance and address any problems.
  2. Optimize for Performance:
    • Fine-tune parameters like flow table update intervals, packet forwarding rules, or link cost calculations to expand network efficiency.
  3. Re-Test:
    • Run the simulation again with the optimized protocol to support improvements.

In this particulars, we include more detailed analysis describe flow based routing module, to implement this logic in C++, and to execute Flow based routing using INET framework in OMNeT++. Further informations will be provided based on your needs. If you’re looking to implement flow-based routing in the OMNeT++ tool for your project, don’t hesitate to reach out to us! We’re here to help you achieve the best results possible.