How to Implement Daisy Chain Topology in NS2

 

To implement the Daisy Chain Topology in Network Simulator 2 (ns2), this topology is a simplified network topology with every node is linked to precisely two other nodes, apart from the two end nodes that are connected to only one other node. It combines a linear chain of nodes. In ns2, you can replicate it by linking nodes with duplex links in a sequence, making the daisy chain. Be in touch with us for tailored services on implementation. Here is the demonstration of how to approach the daisy chain topology in ns2:

Steps to Implement Daisy Chain Topology in NS2:

  1. Set Up the Daisy Chain Topology:
    • Design the nodes.
    • Link each node to the next in sequence using duplex links, apart from the two end nodes, which are connected to only one other node.
  2. Simulate Traffic Flow:
    • Produce traffic amongst two nodes, permitting the data to traverse intermediate nodes over the chain.

Example of Daisy Chain Topology Implementation in NS2:

Follow the below sample script that demonstrates how to configure a daisy chain topology with traffic flowing among two nodes:

# 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 daisy chain 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 daisy chain

$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

# Define TCP agents for communication between nodes

set tcp0 [new Agent/TCP]

set sink0 [new Agent/TCPSink]

$ns attach-agent $n0 $tcp0

$ns attach-agent $n4 $sink0

$ns connect $tcp0 $sink0

# Simulate FTP traffic from node 0 to node 4 (across the daisy chain)

set ftp0 [new Application/FTP]

$ftp0 attach-agent $tcp0

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

# 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 in the daisy chain topology.
  2. Links:
    • Duplex links are generated amongst consecutive nodes, developing a linear chain. For instance, n0 is connected to n1, n1 is linked to n2, and so on, until n3 is linked to n4.
  3. Traffic Simulation:
    • Use the TCP agents to simulate interaction amongst the first node (n0) and the last node (n4), with traffic flowing across the intermediate nodes.
    • Use the FTP (File Transfer Protocol) to produce traffic, replicating a file transfer from n0 to n4.
    • The FTP traffic begins at 1.0 seconds in the simulation.
  4. Simulation Duration:
    • The simulation executes for 10 seconds, enabling traffic to flow from the first node to the last node across the chain.

Post-Simulation Analysis:

  1. Trace File Analysis:
    • Measure how packets are moved from one node to another beside the chain by opening the trace file (out.tr). You can compute metrics includes packet delivery, delay, and throughput for the point-to-point communication.
  2. NAM Visualization:
    • NAM (Network Animator) is used to visualize the daisy chain topology. You will observe the linear arrangement of nodes and how traffic flows from the starting node to the ending node over the intermediate nodes.
  3. Performance Metrics:
    • Measure network performance metrics such as delay, throughput, and packet loss to assess how well the daisy chain topology handles traffic.

Enhancing the Simulation:

  1. Traffic in Both Directions:
    • Configure extra traffic in the reverse direction (from n4 to n0) to replicate bidirectional communication beside the daisy chain.
  2. Changing Traffic Type:
    • You can substitute TCP with UDP or use CBR (Constant Bit Rate) rather than FTP to simulate several variants of traffic and compute how the network functions.
  3. Adding More Nodes:
    • Extend the daisy chain and monitor how performance varies with a longer chain of nodes by attaching more nodes.
  4. Varying Link Parameters:
    • Research with various link parameters like bandwidth, delay, and queue type (e.g., DropTail or RED) to learn how the network performance differs under various conditions.
  5. Simulating Link Failures:
    • Replicate link failures to see how the disruption of a link in the chain impacts communication. In a daisy chain, the failure of a individual link can isolate fragment of the network.

In the comprehensive manual, we were guided and helped you to get started by defining network topology and then simulating a basic Daisy Chain Topology in ns2 and its enhancement features. You can also analyze the simulation. If you need any details for further references, we can provide you.