How to Implement Circular Topology in NS2

To implement the circular topology in ns2, this topology is also known as a ring topology which is a network arrangement with each node is linked to precisely two other nodes, making a closed loop or circle. In this topology, data travels in one or both directions around the ring until it reaches its end point. We can execute this topology by linking nodes in a circular sequence, making sure that the first node links backs to the last node, creating a ring.

In the given procedure, we offered the entire instructions regarding the implementation of Circular Topology in ns2:

Steps to Implement Circular Topology in NS2:

  1. Set Up the Circular Network Topology:
    • State the nodes.
    • Generate duplex links amongst consecutive nodes to form a ring, including a link from the last node back to the first node.
  2. Simulate Traffic Flow:
    • Produce traffic amongst nodes and permit it to traverse around the circle, passing through intermediate nodes if needed.

Example of Circular Topology Implementation in NS2:

Below is an example script that demonstrates how to configure a circular (ring) topology with 5 nodes and simulate traffic amidst them:

# Create a new simulator

set ns [new Simulator]

# Open trace file for output

set tracefile [open out.tr w]

$ns trace-all $tracefile

# Define nodes for the circular topology (5 nodes for simplicity)

set n0 [$ns node]  ;# Node 0

set n1 [$ns node]  ;# Node 1

set n2 [$ns node]  ;# Node 2

set n3 [$ns node]  ;# Node 3

set n4 [$ns node]  ;# Node 4

# Create duplex links to form the circular topology (ring)

$ns duplex-link $n0 $n1 1Mb 10ms DropTail  ;# Link between node 0 and node 1

$ns duplex-link $n1 $n2 1Mb 10ms DropTail  ;# Link between node 1 and node 2

$ns duplex-link $n2 $n3 1Mb 10ms DropTail  ;# Link between node 2 and node 3

$ns duplex-link $n3 $n4 1Mb 10ms DropTail  ;# Link between node 3 and node 4

$ns duplex-link $n4 $n0 1Mb 10ms DropTail  ;# Link between node 4 and node 0 (closing the ring)

# Define TCP agents for communication between nodes

# Traffic from node 0 to node 3 (across the ring)

set tcp0 [new Agent/TCP]

set sink0 [new Agent/TCPSink]

$ns attach-agent $n0 $tcp0

$ns attach-agent $n3 $sink0

$ns connect $tcp0 $sink0

# Simulate FTP traffic from node 0 to node 3

set ftp0 [new Application/FTP]

$ftp0 attach-agent $tcp0

$ns at 1.0 “$ftp0 start”   ;# Start traffic at 1 second

# Traffic from node 1 to node 4 (across the ring)

set tcp1 [new Agent/TCP]

set sink1 [new Agent/TCPSink]

$ns attach-agent $n1 $tcp1

$ns attach-agent $n4 $sink1

$ns connect $tcp1 $sink1

# Simulate FTP traffic from node 1 to node 4

set ftp1 [new Application/FTP]

$ftp1 attach-agent $tcp1

$ns at 2.0 “$ftp1 start”   ;# Start traffic at 2 seconds

# End the simulation after 10 seconds

$ns at 10.0 “finish”

proc finish {} {

global ns tracefile

$ns flush-trace

close $tracefile

exit 0

}

# Run the simulation

$ns run

Explanation of the Script:

  1. Nodes:
    • n0, n1, n2, n3, and n4 indicate the five nodes linked in a circular (ring) topology.
  2. Links:
    • Duplex links are generated amongst consecutive nodes, creating the ring topology. For instance, n0 is linked to n1, n1 is linked to n2, and so on. The final link from n4 back to n0 completes the circular structure.
  3. Traffic Simulation:
    • TCP agents simulate communication amongst nodes.
    • FTP (File Transfer Protocol) creates traffic amongst the nodes, replicating file transfers.
    • In this instance, traffic flows from n0 to n3 (which may pass through intermediate nodes relying on the routing) and from n1 to n4.
  4. Simulation Duration:
    • The simulation runs for 10 seconds, permitting traffic to flow through the circular network.

Post-Simulation Analysis:

  1. Trace File Analysis:
    • Evaluate how packets are forwarded amongst nodes sideways the ring by opening the trace file (out.tr). Assess metrics like packet delivery, delay, and throughput for interaction amongst the nodes.
  2. NAM Visualization:
    • NAM (Network Animator) is used to visualize the circular topology. You will see the nodes linked in a loop, forming a ring, and how traffic flows between them.
  3. Performance Metrics:
    • Analyze how well the circular topology manages traffic by computing network performance metrics like delay, throughput, and packet loss.

Enhancing the Simulation:

  1. Simulating Traffic in Both Directions:
    • Replicate bidirectional communication along the ring by configuring extra traffic in the reverse direction (e.g., from n4 to n1).
  2. Changing Traffic Type:
    • Substitute TCP with UDP or use CBR (Constant Bit Rate) rather than FTP to simulate various types of traffic and measure how the network functions.
  3. Adding More Nodes:
    • Include more nodes to expand the circular topology and monitor how performance differs with a larger ring of nodes.
  4. Varying Link Parameters:
    • Research with various link parameters includes bandwidth, delay, and queue type (for instance: DropTail or RED) to learn how the network performance vary under different conditions.
  5. Simulating Link Failures:
    • Monitor how the circular topology manages disruptions by simulating link failures (for instance: disconnect the link among n1 and n2). In a ring topology, data can regularly be redirected in the opposite direction to reach the destination.

In conclusion, we were provide the step-by-step demonstration on how to approach the implementation of circular topology also called ring topology in the network simulation using ns2 tool. You can enhance the topology, analyze and visualize the simulation output by following the given instructions with examples. For best Circular Topology in NS2 implementation support you can stay in touch with ns2project.com for best guidance. We provide you best topic assistance.