How to Begin Implement ODMRP Protocol in NS3

To implement the On-Demand Multicast Routing Protocol (ODMRP) using NS3 that encompasses to create and code the functionality of multicast routing protocol. ODMRP is a mesh-based and on-demand routing protocol which is particularly intended for multicast interaction within ad-hoc networks.

Here’s a step-by-step procedure on how to execute the ODMRP in NS3:

Steps to Begin Implement ODMRP Protocol in NS3

Step 1: Understand ODMRP Protocol

Make known about the ODMRP protocol before diving into the execution:

• Key Features:
  • Soft-state maintenance of routes and group memberships.
  • Flooding-based route discovery.
  • Mesh-based multicast routing.
• Protocol Components:
  • Route Request (Join Query): Transmission to introduce the routes and association.
  • Route Reply (Join Reply): Again transmit by opposite path for verifying the membership.

Step 2: Familiarize Yourself with NS3 Multicast Routing

• Focus on NS3’s existing multicast routing protocols for knowing about how they are organized. For instance:
  • OLSR (src/olsr/).
  • AODV (src/aodv/).
  • DSDV (src/dsdv/).
• Be familiar with Ipv4RoutingProtocol base class of NS3 that we can prolong to execute the ODMRP.

Step 3: Setup NS3 Environment

1. Create a New Protocol Directory:
   • Make a protocol directory for ODMRP in src/ like src/odmrp/.
2. Add Necessary Files:
   • odmrp-routing-protocol.h: Describe the protocol class and their methodology.
   • odmrp-routing-protocol.cc: Execute the protocol logic.
   • odmrp-helper.h and odmrp-helper.cc: Make a helper class which is used for simulation scripts.
3. Update NS3 Build System:
   • Fine-tune the wscript in src/ with new protocol directory.

Step 4: Design and Implement ODMRP Components

1. Define ODMRP Class

Execute the ODMRP for prolonging ns3::Ipv4RoutingProtocol:

#include “ns3/ipv4-routing-protocol.h”

#include “ns3/ipv4-address.h”

#include “ns3/timer.h”

#include “ns3/socket.h”

class OdmrpRoutingProtocol : public ns3::Ipv4RoutingProtocol {

public:

static ns3::TypeId GetTypeId (void);

OdmrpRoutingProtocol ();

virtual ~OdmrpRoutingProtocol ();

// Ipv4RoutingProtocol methods

virtual ns3::Ptr<ns3::Ipv4Route> RouteOutput (

ns3::Ptr<const ns3::Packet> packet,

const ns3::Ipv4Header &header,

ns3::Ptr<ns3::NetDevice> oif,

ns3::Socket::SocketErrno &sockerr);

virtual bool RouteInput (

ns3::Ptr<const ns3::Packet> packet,

const ns3::Ipv4Header &header,

ns3::Ptr<const ns3::NetDevice> idev,

ns3::UnicastForwardCallback ucb,

ns3::MulticastForwardCallback mcb,

ns3::LocalDeliverCallback lcb,

ns3::ErrorCallback ecb);

// ODMRP-specific methods

void StartRouteDiscovery (ns3::Ipv4Address multicastGroup);

void ProcessJoinQuery (ns3::Ptr<const ns3::Packet> packet, ns3::Ipv4Address sender);

void SendJoinReply (ns3::Ipv4Address group, ns3::Ipv4Address sender);

private:

ns3::Ipv4Address m_selfAddress;

std::map<ns3::Ipv4Address, std::set<ns3::Ipv4Address>> m_multicastMesh; // Mesh structure

ns3::Timer m_routeRefreshTimer; // Timer for route maintenance

};

2. Implement Packet Structure

Describe custom packet headers to leverage ns3::Header for ODMRP.

#include “ns3/header.h”

class OdmrpHeader : public ns3::Header {

public:

static ns3::TypeId GetTypeId (void);

virtual TypeId GetInstanceTypeId () const;

void SetGroupAddress (ns3::Ipv4Address addr);

void SetSenderAddress (ns3::Ipv4Address addr);

virtual void Serialize (ns3::Buffer::Iterator start) const;

virtual uint32_t Deserialize (ns3::Buffer::Iterator start);

virtual void Print (std::ostream &os) const;

private:

ns3::Ipv4Address m_groupAddress;

ns3::Ipv4Address m_senderAddress;

};

3. Join Query and Reply Logic

• Join Query:
  • Transmit a JoinQuery packet for determining the optimal paths and memberships.
  • With the support of flooding including methods for preventing loops such as sequence numbers.
• Join Reply:
  • Reply by opposite path for verifying the membership.
  • For multicast group members, we can sustain soft-state accesses.

Example:

void OdmrpRoutingProtocol::StartRouteDiscovery (ns3::Ipv4Address multicastGroup) {

OdmrpHeader joinQuery;

joinQuery.SetGroupAddress(multicastGroup);

joinQuery.SetSenderAddress(m_selfAddress);

// Create and broadcast the JoinQuery packet

ns3::Ptr<ns3::Packet> packet = ns3::Create<ns3::Packet>();

packet->AddHeader(joinQuery);

BroadcastPacket(packet);

}

void OdmrpRoutingProtocol::ProcessJoinQuery (ns3::Ptr<const ns3::Packet> packet, ns3::Ipv4Address sender) {

OdmrpHeader header;

packet->PeekHeader(header);

// Check if the node is part of the multicast group

if (IsGroupMember(header.GetGroupAddress())) {

SendJoinReply(header.GetGroupAddress(), sender);

}

}

4. Maintain Multicast Mesh

• Save mesh memberships utilising a table.
• Leverage timers to restore paths periodically.

Step 5: Create Helper Class

Execute a helper class within simulation scripts for simple installation:

class OdmrpHelper {

public:

void Install (ns3::NodeContainer nodes);

};

Step 6: Write Simulation Script

Make a simulation script to experiment the ODMRP protocol. For instance:

#include “ns3/core-module.h”

#include “ns3/network-module.h”

#include “ns3/internet-module.h”

#include “odmrp-helper.h”

int main () {

ns3::NodeContainer nodes;

nodes.Create(5);

OdmrpHelper odmrpHelper;

odmrpHelper.Install(nodes);

// Create multicast traffic and simulate

ns3::Simulator::Run();

ns3::Simulator::Destroy();

return 0;

}

Step 7: Build and Run

1. Build NS3 with ODMRP:

./waf configure

./waf build

1. Run Simulation:

./waf –run your-script

Step 8: Validate and Extend

• Validation:
  • Record and examine the behaviour of protocol with NS3 tracing tools such as AsciiTraceHelper, PcapHelper.
• Metrics:
  • Assess the performance of ODMRP to apply performance parameters such as packet delivery ratio, end-to-end delay, and control overhead.
• Enhancements:
  • Integrate enhancements such as mobility handling, minimized flooding, or enhanced mesh maintenance.

From this methodology, we can thoroughly know how to start implementing and executing the ODMRP Protocol using NS3 environment. If you have any doubts about this topic, we will help you out of it.