How to Start Mixed Topology Projects Using NS2

To create a Mixed Topology in NS2 (Network Simulator 2) has includes the associate of many network topologies for sample star, ring, tree, mesh, etc. in a single network. This is beneficial for design the real-world networks in which frequently have hybrid architecture.

Here’s how to start your Mixed Topology project in NS2:

Steps to Simulate Mixed Topology in NS2

  1. Understand Mixed Topology
  • Structure:
    • It associates the several network topologies for sample a tree connected to a ring, or a star linked to a mesh.
    • Logical connections are linking the nodes with changed topologies.
  • Applications:
    • Real-world networks such as enterprise or campus networks.
    • Validate the interoperability and incorporate the various topologies.
  1. Set Up NS2
  1. Install NS2:

sudo apt-get install ns2

  1. Verify Installation: Validate by a simple replication of script:

ns example.tcl

  1. Define Mixed Topology
  • Select the combination for topologies for instance star + ring, tree + mesh.
  • Describe the nodes and connection for every topology.
  • Interconnect the altered topologies for make use the logical connections.
  1. TCL Script for Mixed Topology

Below is a sample TCL script for replicate the Mixed Topology combining a Star Topology and a Ring Topology:

TCL Script Example

# Initialize NS2 Simulator

set ns [new Simulator]

set tracefile [open mixed_topology.tr w]

$ns trace-all $tracefile

 

# Define the Star Topology

set hub [$ns node]  # Central hub for the star

set star_nodes 4    # Number of nodes in the star

# Create nodes for the star topology

for {set i 0} {$i < $star_nodes} {incr i} {

set star($i) [$ns node]

$ns duplex-link $hub $star($i) 1Mb 10ms DropTail

}

# Define the Ring Topology

set ring_nodes 5    # Number of nodes in the ring

# Create nodes for the ring topology

for {set i 0} {$i < $ring_nodes} {incr i} {

set ring($i) [$ns node]

}

# Create links for the ring topology

for {set i 0} {$i < $ring_nodes} {incr i} {

set next [expr ($i + 1) % $ring_nodes]

$ns simplex-link $ring($i) $ring($next) 1Mb 5ms DropTail

}

# Interconnect the topologies

# Connect the hub of the star to a node in the ring

$ns duplex-link $hub $ring(0) 2Mb 15ms DropTail

# Attach agents for traffic simulation

# Example: Traffic from a star node to a ring node

set tcp0 [new Agent/TCP]

$ns attach-agent $star(1) $tcp0

set sink0 [new Agent/TCPSink]

$ns attach-agent $ring(3) $sink0

$ns connect $tcp0 $sink0

# Add a traffic generator

set ftp [new Application/FTP]

$ftp attach-agent $tcp0

# Start traffic

$ns at 1.0 “$ftp start”

# End simulation

$ns at 5.0 “finish”

proc finish {} {

global ns tracefile

$ns flush-trace

close $tracefile

exit 0

}

$ns run

  1. Key Features to Simulate
  1. Inter-Topology Traffic:
    • It assures the transmission among nodes in changed topologies.
  2. Performance Metrics:
    • Throughput: Amount of data delivery among their nodes in various topologies.
    • Latency: Examine the delays are established through inter-topology communication.
    • Packet Loss: It estimates the packet loss for reliability.
  1. Analyze Trace File
  • It can use the trace file such as mixed_topology.tr for examine the network performance.
  • Excerpt the detailed performance of parameter metrics:
    • Throughput:

grep “tcp” mixed_topology.tr > throughput.log

    • Dropped Packets:

grep “drop” mixed_topology.tr > dropped_packets.log

  1. Visualize Results

It use the outcomes for Gnuplot or alternative tool used for the envision:

  1. Throughput Graph:

set title “Mixed Topology Throughput”

plot “throughput.log” using 1:2 with lines title “Throughput”

  1. Latency Graph:
    • Associate the delays for intra- and inter-topology communication.
  1. Extend the Simulation
  2. Add More Topologies
  • Incorporate the added topologies for instance mesh, tree:

set tree_root [$ns node]

set tree_child1 [$ns node]

set tree_child2 [$ns node]

$ns duplex-link $tree_root $tree_child1 1Mb 10ms DropTail

$ns duplex-link $tree_root $tree_child2 1Mb 10ms DropTail

  1. Dynamic Topology Behavior
  • It replicate the dynamic variations in topology:

$ns at 3.0 “$ns duplex-link $ring(2) $star(2) 1Mb 10ms DropTail”

  1. Test Different Traffic Patterns
  • Improve the congestion among their nodes in various topologies:

set udp1 [new Agent/UDP]

$ns attach-agent $ring(1) $udp1

set null1 [new Agent/Null]

$ns attach-agent $star(3) $null1

$ns connect $udp1 $null1

  1. Simulate Node or Link Failures
  • Disconnect connection or nodes dynamically during the repliction:

$ns at 2.5 “$ns reset-links $hub $star(2)”

  1. Modify NS2 Core for Advanced Features
  1. Dynamic Interconnections:
    • Execute the procedures for choose the dynamic path among topologies.
  2. Custom Traffic Behavior:
    • Alter the recv() method in the main of enhance detailed the inter-topology routing logic.

Tools and Resources

  • Wireshark: Examine the congestion design for inter-topology communication.
  • Gnuplot: Envision for the performance of parameter metrics such as throughput and delay.
  • NS2 Documentation: Mention for generating and changing topologies.

Enhancements

  • Replicate the Real-World Networks:
    • It associates the topologies for design the realistic network environments such as campuses or enterprise networks.
  • Compare Mixed Topology vs Single Topology:
    • Examine the various in performance, scalability, and fault tolerance.
  • Add QoS Models:
    • Prioritize for congestion among the complex nodes or topologies.

From the follow steps, we had successfully implemented the mixed topology using the ns2 tool that has to apply the performance mechanisms then follow the relevant topology events and estimate the metrics to execute the process. We provide the additional details concerning the mixed topology.