How to Start Metropolitan Area Networks Projects Using NS2

To start a Metropolitan Area Network (MAN) project in Network Simulator 2 (NS2), we can follow these structured steps. Following is a basic guide to know the simulation procedure, from setup to executing and testing the MAN projects in NS2.

Steps to Start MAN Projects in NS2

Step 1: Install NS2

  1. Download NS2: NS2 is a robust network simulator which is utilized in research and educational purposes. We can set up NS2 environment on the system to utilise NS2 website and GitHub repositories based on operating systems.
    • For Linux (Ubuntu):

sudo apt-get install ns2

    • We will need to observe the installation instruction on the official NS2 website for macOS or Windows.
  2. Install Dependencies: NS2 environment needs more packages such as TCL, Xgraph, and OTcl. Make sure these are installed properly.
  3. Verify Installation: Confirm installation in the terminal and type:

ns

If it opens the NS2 support then the installation is effectively functioned.

Step 2: Understand NS2 and Metropolitan Area Networks

A Metropolitan Area Network (MAN) contains a larger geographical area than a local area network (LAN) however it is smaller than a wide-area network (WAN). MANs are utilized for connecting diverse networks in a city or a campus.

We must know about the key features of MAN before starting the project:

  • Topologies: MAN topologies contain mesh, tree, and hybrid topology.
  • Routing Protocols: Generally used routing protocols are OSPF, RIP, BGP, and so on, within MAN.
  • Traffic Patterns: We can replicate diverse traffic models like multimedia, VoIP, and standard data traffic.

Step 3: Define Your MAN Scenario

Make a Metropolitan Area Network, we can deliberate:

  • Number of Nodes: Determine how many nodes like routers, switches, and end systems to replicate.
  • Network Topology: Select an appropriate network topology like a mesh or hybrid. A basic mesh topology associates every single node to each other node but a tree topology links the nodes within a hierarchical structure.
  • Protocols: Decide on the network protocols according to the needs of simulation. We will need to utilise the TCP, UDP, and routing protocols like OSPF, RIP.
  • Traffic Generation: Describe the traffic pattern as CBR, FTP, and HTTP for replicating data flows.

Step 4: Writing NS2 Scripts

NS2 environment uses the OTcl (Object-Oriented Tcl) for simulation entities and utilises Tcl (Tool Command Language) for scripting simulations. Below is a basic instance of an NS2 script for a simple network simulation:

Example Code (Tcl):

# Define simulation

set ns [new Simulator]

# Create two nodes (for simplicity)

set node1 [$ns node]

set node2 [$ns node]

# Define links between nodes (speed, delay, queue size)

$ns duplex-link $node1 $node2 1Mb 10ms DropTail

# Define TCP and application

set tcp [new Agent/TCP]

$ns attach-agent $node1 $tcp

set sink [new Agent/TCPSink]

$ns attach-agent $node2 $sink

$ns connect $tcp $sink

# Define FTP application

set ftp [new Application/FTP]

$ftp attach-agent $tcp

# Set simulation time and run

$ns run

This script configures a basic network containing two nodes, a link among them, a TCP agent, and an FTP application for replicating the data transfer.

Key Points in the Code:

  • Node Creation: Nodes denotes the routers or end systems.
  • Link Creation: Specifies the metrics like bandwidth, delay, and queue size among nodes.
  • TCP Agent: It is utilised for replicating data transfer among nodes.
  • FTP Application: A basic application to mimic file transfer amongst nodes.

Step 5: Extend the Simulation for MAN

We have fundamentals to prolong the simulation for a Metropolitan Area Network:

  1. Multiple Nodes: In the topology, make additional nodes. For instance:

set node1 [$ns node]

set node2 [$ns node]

set node3 [$ns node]

set node4 [$ns node]

  1. Complex Topology: We can utilise additional sophisticated topologies such as mesh, hybrid. NS2 environment permits for creating custom topologies by way of defining the location of node.
  2. Routing Protocols: If we will want to route then add routing protocols such as OSPF, AODV, or DSR. For instance:

set ragent [new Agent/RSVP]

  1. Traffic and Applications: Integrate several traffic models and applications such as:
    • CBR (Constant Bit Rate): Replicating real-time services like VoIP or video conferencing.
    • FTP/HTTP: Mimicking bulk data transfer.

Example for CBR:

set cbr [new Application/Traffic/CBR]

Step 6: Run the Simulation

When the simulation script is prepared then we run the simulation using NS2 environment:

ns yourscript.tcl

It will be replicated the network scenario, and we will normally obtain output within trace files.

Step 7: Analyze the Results

When simulation is executed then NS2 environment makes trace files, which offer in-depth data regarding packet delivery, delays, routing paths, and more.

To examine the trace files:

  1. Use Xgraph: It is utilised for graphical representations of data such as packet arrival times.

xgraph tracefile.tr

  1. Custom Analysis: Inscribe custom scripts to utilise external tools like Python or MATLAB for executing the output trace files and acquiring performance parameters like:
    • Loss rate
    • End-to-end delay
    • Throughput
    • Packet delivery ratio

Step 8: Fine-Tune and Experiment

To enhance the simulation:

  • Modify the network topology or traffic models for estimating the various scenarios.
  • Launch failures like link failure, node failure to experiment the MAN’s robustness.
  • Test with various routing mechanisms to observe how they impact the performance.

Step 9: Documentation and Reporting

It offers detailed a report or documentation, which contains:

  • Simulation design including topology, protocols, traffic patterns.
  • Simulation results with graphs and parameters.
  • Analysis and conclusions according to the outcomes.

We had offered strong foundation for starting and simulating the Metropolitan Area Network project using NS2, and estimating network performance in diverse conditions. More  advanced topic will be added in upcoming manual.