How to Begin Implement Multiprotocol Label Switching in NS3

To implement the Multiprotocol Label Switching (MPLS) in NS-3 environment has been contain a generate framework for label-based packet sending. The MPLS is generally used to network efficiency and scalability through routing packets according to their labels rather than IP addresses. Here’s a step-by-step guide to implementing MPLS in NS-3:

Steps to Begin Implement Multiprotocol Label Switching in NS3

Step 1: Understand MPLS

1. Key Concepts:
   • Label Switched Path (LSP): The LSP has pre-determined path for packet sending.
   • Label Switching Router (LSR): The router which forwards the packets according to labels.
   • Label Distribution Protocol (LDP): Allocates the labels among routers.
   • Forwarding Equivalence Class (FEC): Group of packets are transmitted equally.
2. Core MPLS Functions:
   • Label works the push, pop, and swap.
   • The LSPs are configured and handling.
   • Effective sending according to their labels.

Step 2: Set Up NS-3 Development Environment

1. Create a New Protocol Directory:
   • Below the src/, generate a directory for MPLS for sample src/mpls/.
2. Add Required Files:
   • mpls-routing-protocol.h: Header file are require the MPLS protocol.
   • mpls-routing-protocol.cc: the execute the file.
   • mpls-helper.h and mpls-helper.cc: Helper files for simple replication setting.
3. Update Build System:
   • Alter the system like wscript in the src/ directory for contain the MPLS component.

Step 3: Design MPLS Components

1. MPLS Header

Describe the header class for maintain the MPLS labels.

#include “ns3/header.h”

class MplsHeader : public ns3::Header {

public:

static ns3::TypeId GetTypeId (void);

virtual TypeId GetInstanceTypeId () const;

void SetLabel (uint32_t label);

uint32_t GetLabel () const;

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

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

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

private:

uint32_t m_label; // MPLS label

};

2. Label Switching Table

Maintain a table for label-based forwarding.

#include “ns3/ipv4-address.h”

class LabelSwitchingTable {

public:

void AddEntry (uint32_t incomingLabel, uint32_t outgoingLabel, ns3::Ipv4Address nextHop);

bool Lookup (uint32_t incomingLabel, uint32_t &outgoingLabel, ns3::Ipv4Address &nextHop);

private:

struct TableEntry {

uint32_t incomingLabel;

uint32_t outgoingLabel;

ns3::Ipv4Address nextHop;

};

std::vector<TableEntry> m_table;

};

3. MPLS Protocol Class

Encompass the class for MPLS Ipv4RoutingProtocol.

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

#include “mpls-header.h”

#include “label-switching-table.h”

class MplsRoutingProtocol : public ns3::Ipv4RoutingProtocol {

public:

static ns3::TypeId GetTypeId (void);

MplsRoutingProtocol ();

virtual ~MplsRoutingProtocol ();

// 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);

// MPLS-specific methods

void SetupLSP (uint32_t label, ns3::Ipv4Address nextHop);

void HandleMplsPacket (ns3::Ptr<const ns3::Packet> packet);

private:

LabelSwitchingTable m_labelTable;

};

4. LSP Setup and Label Forwarding

Estimate the LSP setting and handling the label-based packet.

void MplsRoutingProtocol::SetupLSP (uint32_t label, ns3::Ipv4Address nextHop) {

// Add an entry in the label switching table

m_labelTable.AddEntry(label, label + 1, nextHop);

}

void MplsRoutingProtocol::HandleMplsPacket (ns3::Ptr<const ns3::Packet> packet) {

MplsHeader header;

packet->PeekHeader(header);

uint32_t outgoingLabel;

ns3::Ipv4Address nextHop;

if (m_labelTable.Lookup(header.GetLabel(), outgoingLabel, nextHop)) {

// Forward packet to next hop

header.SetLabel(outgoingLabel);

packet->AddHeader(header);

// Use socket or NetDevice to send packet

}

}

Step 4: Write a Helper Class

Enable installation and setting for replication scripts.

#include “mpls-routing-protocol.h”

class MplsHelper {

public:

void Install (ns3::NodeContainer nodes) {

for (auto it = nodes.Begin(); it != nodes.End(); ++it) {

ns3::Ptr<MplsRoutingProtocol> protocol = ns3::CreateObject<MplsRoutingProtocol>();

(*it)->AggregateObject(protocol);

}

}

};

Step 5: Write Simulation Script

Generate a replication of script to experiment MPLS functionality.

#include “ns3/core-module.h”

#include “ns3/network-module.h”

#include “ns3/internet-module.h”

#include “mpls-helper.h”

int main () {

ns3::NodeContainer nodes;

nodes.Create(4);

ns3::InternetStackHelper stack;

stack.Install(nodes);

MplsHelper mplsHelper;

mplsHelper.Install(nodes);

// Create LSPs

ns3::Ptr<MplsRoutingProtocol> mpls1 = nodes.Get(0)->GetObject<MplsRoutingProtocol>();

ns3::Ptr<MplsRoutingProtocol> mpls2 = nodes.Get(1)->GetObject<MplsRoutingProtocol>();

mpls1->SetupLSP(10, ns3::Ipv4Address(“10.0.0.2”));

mpls2->SetupLSP(11, ns3::Ipv4Address(“10.0.0.3”));

// Set up traffic sources and sinks

ns3::Simulator::Run();

ns3::Simulator::Destroy();

return 0;

}

Step 6: Compile and Run

1. Build:

./waf configure

./waf build

1. Run Simulation:

./waf –run your-script

Step 7: Validate and Extend

• Validation:
  • Validate the forwarding a label-based using NS-3 tracing tools.
  • Authorize LSP setting and routing behavior.
• Extensions:
  • Apply the Label Distribution Protocol (LDP) for automated label management.
  • Enhance the QoS mechanisms for priority-based routing.

Step 8: Analyze Results

Tracing tools utilized like PcapHelper or AsciiTraceHelper to examine the packet flow and validate the MPLS behavior.

In this demonstration, we completely know how to simulate the basic setup simulation and to know how to execute the Multiprotocol Label Switching in ns3 simulator tool. A secondary manual will provide answers to any further questions about this project.