How to Implement MPLS Protocol in NS2

To implement the MPLS (Multiprotocol Label Switching) in NS2, we have to extend the simulation with MPLS mechanisms because MPLS is not supported in NS2. MPLS is a data-carrying strategy that allocates labels to packets and uses these labels to move the packets at high speeds. We have to simulate the basic MPLS functions as well as label distribution, label switching and path set up for the execution of MPLS in ns2.

In the following, we provide the step-by-step guide to implementing MPLS in NS2:

Step-by-Step Implementation:

Step 1: Install NS2

Make sure that you have installed and configured the ns2 on your computer. Follow the installation instructions specific to your operating system.

Step 2: Understanding MPLS Basics

MPLS operates by allocating labels to packets. Routers (called Label Switching Routers or LSRs) forward packets depends on the labels instead of the IP addresses, enabling faster and more efficient routing.

Step 3: Set Up the NS2 Environment for MPLS

  1. Extend NS2 with MPLS support: To simulate the MPLS behavior, we have to expand the ns2 by attaching custom C++ code or scripts, because MPLS is not directly supported in your NS2 installation. Some NS2 versions or extensions might already have basic MPLS support.
  2. Download and install MPLS patches or extensions: There are patches existed that add MPLS support to NS2. These patches can be discovers in various repositories or academic websites. Download and apply these patches to your NS2 installation.

Step 4: Create a Simulation Script

Set up the network and simulate MPLS routing by generating a Tcl Script.

Example: Basic MPLS Setup in NS2

  1. Create a New Tcl Script: Open a text editor and generate a new file like mpls_example.tcl.
  2. Set Up the Simulation Environment: Configure the simulator, network topology, and basic parameters.

# Create a simulator object

set ns [new Simulator]

# Define options for the simulation

set val(chan)   Channel/WirelessChannel    ;# Channel type

set val(prop)   Propagation/TwoRayGround   ;# Propagation model

set val(netif)  Phy/WirelessPhy            ;# Network interface type

set val(mac)    Mac/802_11                 ;# MAC type

set val(ifq)    Queue/DropTail/PriQueue    ;# Interface Queue type

set val(ll)     LL                         ;# Link layer type

set val(ant)    Antenna/OmniAntenna        ;# Antenna type

set val(ifqlen) 50                         ;# Max packet in ifq

set val(nn)     5                          ;# Number of nodes

set val(x)      500                        ;# X dimension of topography

set val(y)      500                        ;# Y dimension of topography

set val(stop)   10.0                       ;# Simulation time

# Initialize the topology object

set topo [new Topography]

$topo load_flatgrid $val(x) $val(y)

# Create the God object

create-god $val(nn)

# Configure the nodes (LSRs – Label Switching Routers)

$ns node-config -llType $val(ll) \

-macType $val(mac) \

-ifqType $val(ifq) \

-ifqLen $val(ifqlen) \

-antType $val(ant) \

-propType $val(prop) \

-phyType $val(netif) \

-channelType $val(chan) \

-topoInstance $topo \

-agentTrace ON \

-routerTrace ON \

-macTrace ON \

-movementTrace ON

# Create nodes (LSRs)

for {set i 0} {$i < $val(nn)} {incr i} {

set node_($i) [$ns node]

}

# Define node positions (for clarity)

$node_(0) set X_ 100.0

$node_(0) set Y_ 100.0

$node_(1) set X_ 200.0

$node_(1) set Y_ 200.0

$node_(2) set X_ 300.0

$node_(2) set Y_ 100.0

$node_(3) set X_ 400.0

$node_(3) set Y_ 200.0

$node_(4) set X_ 500.0

$node_(4) set Y_ 100.0

# Setup links between LSRs

$ns duplex-link $node_(0) $node_(1) 1Mb 10ms DropTail

$ns duplex-link $node_(1) $node_(2) 1Mb 10ms DropTail

$ns duplex-link $node_(2) $node_(3) 1Mb 10ms DropTail

$ns duplex-link $node_(3) $node_(4) 1Mb 10ms DropTail

# Setup MPLS-specific logic (requires additional implementation)

# Example: Label distribution, path setup

# You may need to add custom Tcl procedures or call existing MPLS procedures

Step 5: Implement MPLS Logic

Since MPLS is not natively supported in NS2, you will need to execute the core MPLS mechanisms such as:

  • Label Distribution Protocol (LDP): For distributing labels.
  • Label Forwarding: How LSRs forward packets depends on labels.
  • Path Setup: Configuring Label Switched Paths (LSPs).

This may desire writing additional C++ code or extending the Tcl script with custom procedures that imitate MPLS actions.

Step 6: Set Up Traffic Sources

State the communication amongst nodes (such as sending labeled packets).

# Setup a UDP agent and attach it to the first node

set udp [new Agent/UDP]

$ns attach-agent $node_(0) $udp

# Setup a CBR application to generate traffic

set cbr [new Application/Traffic/CBR]

$cbr attach-agent $udp

$cbr set packetSize_ 512

$cbr set interval_ 0.1

$cbr start

# Setup a Null agent (sink) on the last node

set null [new Agent/Null]

$ns attach-agent $node_(4) $null

# Connect the agents

$ns connect $udp $null

Step 7: Define Simulation End

# Define simulation end time

$ns at $val(stop) “stop”

$ns at $val(stop) “$ns nam-end-wireless $val(stop)”

$ns at $val(stop) “exit 0”

proc stop {} {

global ns tracefile namfile

$ns flush-trace

close $tracefile

close $namfile

}

# Run the simulation

$ns run

Step 8: Run the Simulation

  1. Save the Tcl script (mpls_example.tcl).
  2. Open a terminal and route to the directory where you stored the Tcl script.
  3. Execute the simulation using the following command:

ns mpls_example.tcl

This command will produce trace files and optionally a network animation file (if allowed in your script).

Step 9: Analyze the Results

Use trace files and the network animator (NAM) to measure the performance of MPLS aiming on metrics like label distribution, packet delivery ratio, end-to-end delay, and network overhead.

Additional Considerations

  • Implementing MPLS in NS2: If MPLS is not supported natively, you may need to write custom C++ code to execute MPLS functionality in NS2. This involves altering or expanding the available NS2 modules.
  • Patching NS2: Search for patches or extensions that offers MPLS support for NS2, and perform them to your NS2 installation.
  • Testing: Examine MPLS in difference network scenarios to estimate its effectiveness, after the implementation.

This procedure will help you obtain the concept and to implement the Multiprotocol Label Switching Protocol in ns2 and to install the MPLS patches or extensions by following the examples provided above. We also offer their evaluation and simulation steps and how to execute them.

We conduct performance analysis tailored to your needs. Our expertise in MPLS Protocol within NS2 implementation ensures exceptional results. For more information, please reach out to ns2project.com.