How to Implement Multi protocol Label Switching in NS2

To implement the Multiprotocol Label Switching (MPLS) within NS2 has essential to encompass to simulating an environment in which packets are routed according to the labels instead of the old IP addresses. It operates among the data link layer (Layer 2) and the network layer (Layer 3), and these are created to enhance the speed and manageability of network traffic by using the labels attached to the packets.

Step-by-Step Implementation:

Step 1: Understand MPLS Components

Before diving into the execution, it’s needed to know the vital components of the MPLS:

  • Label Edge Router (LER): These routers are operate at the edge of an MPLS network and allocate labels to packets entering the network.
  • Label Switch Router (LSR): This routers are operate in the MPLS network and send packets according to their labels.
  • Label Switched Path (LSP): The path over the MPLS network which is a packet takes, ascertained by the labels.
  • Label Distribution Protocol (LDP): This protocol is used to deliver the labels and establish the label switch routers.

Step 2: Set Up NS2

Make sure that NS2 is installed and operative on the system. MPLS is not natively assist in the simulation tool NS2, thus we will want to execute it by expanding existing classes or making new ones.

Step 3: Implement MPLS in NS2

  1. Create MPLS Classes

We will want to describe the classes for MPLS-related functions like label distribution, label switching, and path setup.

Label Edge Router (LER) and Label Switch Router (LSR) Classes:

#include <agent.h>

#include <packet.h>

#include <trace.h>

#include <address.h>

#include <map>

class MPLSAgent : public Agent {

public:

MPLSAgent();

void recv(Packet* p, Handler* h);

void handleIngress(Packet* p);

void handleTransit(Packet* p);

void handleEgress(Packet* p);

protected:

std::map<int, int> labelTable_;  // Incoming label -> Outgoing label

std::map<int, int> fwdTable_;    // Destination -> Next hop

int assignLabel(int dest);

void sendPacketWithLabel(Packet* p, int label);

};

// Constructor

MPLSAgent::MPLSAgent() : Agent(PT_UDP) {

// Initialize the label and forwarding tables

}

// Packet reception

void MPLSAgent::recv(Packet* p, Handler* h) {

hdr_ip* iph = hdr_ip::access(p);

if (isIngressNode(iph)) {

handleIngress(p);

} else if (isEgressNode(iph)) {

handleEgress(p);

} else {

handleTransit(p);

}

}

// Handle ingress node behavior

void MPLSAgent::handleIngress(Packet* p) {

hdr_ip* iph = hdr_ip::access(p);

int dest = iph->daddr();

int label = assignLabel(dest);

sendPacketWithLabel(p, label);

}

// Handle transit node behavior

void MPLSAgent::handleTransit(Packet* p) {

hdr_ip* iph = hdr_ip::access(p);

int label = labelTable_[iph->label()];  // Get the new label based on the incoming label

sendPacketWithLabel(p, label);

}

// Handle egress node behavior

void MPLSAgent::handleEgress(Packet* p) {

// Remove MPLS label and forward the packet as an IP packet

hdr_ip* iph = hdr_ip::access(p);

iph->label() = 0;  // Remove label

send(p, fwdTable_[iph->daddr()]);

}

// Assign a label to a destination

int MPLSAgent::assignLabel(int dest) {

static int currentLabel = 100;

labelTable_[currentLabel] = fwdTable_[dest];

return currentLabel++;

}

// Send packet with an MPLS label

void MPLSAgent::sendPacketWithLabel(Packet* p, int label) {

hdr_ip* iph = hdr_ip::access(p);

iph->label() = label;  // Attach MPLS label

send(p, fwdTable_[iph->daddr()]);

}

  1. Define Custom Packet Types

We may want to describe the custom packet types for the MPLS if particular MPLS-related control packets are essential:

#define PT_MPLS 60

// Add this to the packet.h file in NS2’s source code

packet_t PT_MPLS;

We would also want to change the ns-default.tcl to accept these packet types.

  1. Integrate MPLS into NS2
  1. Modify the Makefile: Append the new MPLSAgent class to the NS2 Makefile so as to it acquires compiled with the rest of the simulator.
  2. Recompile NS2:

make clean

make

Step 4: Create a Tcl Script to Simulate MPLS

When MPLS execution is prepared, then we make a Tcl script that configures an MPLS network and mimics traffic flow.

Example Tcl Script:

# Create a simulator object

set ns [new Simulator]

# Define the topology

set val(chan)   Channel/WiredChannel

set val(ll)     LL

set val(ifq)    Queue/DropTail/PriQueue

set val(ifqlen) 50

set val(stop)   50.0

# Initialize the topology object

set topo [new Topography]

$topo load_flatgrid 500 500

# Create nodes

set node1 [$ns node]

set node2 [$ns node]

set node3 [$ns node]

# Establish links between nodes

$ns duplex-link $node1 $node2 10Mb 10ms DropTail

$ns duplex-link $node2 $node3 10Mb 10ms DropTail

# Attach MPLS agents to nodes

set mpls1 [new Agent/MPLSAgent]

set mpls2 [new Agent/MPLSAgent]

set mpls3 [new Agent/MPLSAgent]

$ns attach-agent $node1 $mpls1

$ns attach-agent $node2 $mpls2

$ns attach-agent $node3 $mpls3

# Set up traffic sources and sinks

set udp [new Agent/UDP]

set null [new Agent/Null]

$ns attach-agent $node1 $udp

$ns attach-agent $node3 $null

$ns connect $udp $null

# Start sending data from node 1 to node 3

$ns at 0.0 “$udp start”

# Simulation end

$ns at $val(stop) “stop”

$ns at $val(stop) “exit 0”

proc stop {} {

global ns

$ns flush-trace

exit 0

}

# Run the simulation

$ns run

Step 5: Run the Simulation

  1. We can save the Tcl script such as mpls_simulation.tcl.
  2. Open a terminal and navigate to the directory in which we can be saved the Tcl script.
  3. Run the simulation using the given command:

ns mpls_simulation.tcl

Step 6: Analyse the Results

  • We can use the trace files and the network animator (NAM) to estimate the performance of the MPLS protocol.
  • Attention on the parameters like packet delivery ratio, delay, and the efficiency of label-switched paths.

Additional Considerations

  • Label Distribution Protocol (LDP): If required, then execute a basic version of the LDP to handle label distribution between the MPLS nodes.
  • Traffic Engineering: Investigate the ways to execute the traffic engineering features in the MPLS format, like manually configuring LSPs to enhance the network resource usage.
  • Scalability: Examine the MPLS protocol in a bigger network with more nodes to estimate its scalability and effectiveness.

We thoroughly followed a step-by-step approach on Multiprotocol Label Switching, executing and evaluating it through the simulation tool ns2. Additional specifies will be shared using the required simulation tools.

Performance Analysis are carried out by us tailored to your needs. Our expertise in Multiprotocol Label Switching within NS2 implementation ensures you receive outstanding results. Feel free to reach out to ns2project.com for assistance. We also offer excellent project ideas and topics for your consideration.