How to Implement Tree Topology in NS2

 

To implement tree topology in ns2 has series of steps to follow. It can be executed by configuring the nodes in a hierarchical structure in which a root node associates to intermediate nodes (branches), and these intermediate nodes interconnect to leaf nodes (end devices). This structure resembles a tree, in which the root denotes the top node, the branches signify the intermediary nodes, and the leaf nodes are the end nodes at the bottom. If you want best implementation guidance then you can contact us.

Here is an guide to implement the tree topology in ns2:

Steps to Implement a Tree Topology in NS2:

  1. Set Up the Tree Topology:
    • Describe nodes to denote various levels of the tree (root, intermediate, and leaf nodes).
    • Associate the root node to intermediate nodes, and each intermediate node to its respective leaf nodes using duplex links.
  2. Simulate Traffic Flow:
    • Traffic can be created among nodes at different levels of the tree, passing via intermediate nodes.

Example of Tree Topology Implementation in NS2:

Below is an instance of a tree topology with 3 levels: a root node, intermediate nodes, and leaf 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 tree topology (1 root, 2 intermediates, 4 leaves)

set root [$ns node]    ;# Root node (level 1)

set int1 [$ns node]    ;# Intermediate node 1 (level 2)

set int2 [$ns node]    ;# Intermediate node 2 (level 2)

set leaf1 [$ns node]   ;# Leaf node 1 (level 3)

set leaf2 [$ns node]   ;# Leaf node 2 (level 3)

set leaf3 [$ns node]   ;# Leaf node 3 (level 3)

set leaf4 [$ns node]   ;# Leaf node 4 (level 3)

# Create duplex links to form the tree topology

# Connect root to intermediate nodes

$ns duplex-link $root $int1 1Mb 10ms DropTail  ;# Link between root and intermediate 1

$ns duplex-link $root $int2 1Mb 10ms DropTail  ;# Link between root and intermediate 2

# Connect intermediate nodes to leaf nodes

$ns duplex-link $int1 $leaf1 1Mb 10ms DropTail ;# Link between intermediate 1 and leaf 1

$ns duplex-link $int1 $leaf2 1Mb 10ms DropTail ;# Link between intermediate 1 and leaf 2

$ns duplex-link $int2 $leaf3 1Mb 10ms DropTail ;# Link between intermediate 2 and leaf 3

$ns duplex-link $int2 $leaf4 1Mb 10ms DropTail ;# Link between intermediate 2 and leaf 4

# Define TCP agents and sinks for communication between nodes

set tcp0 [new Agent/TCP]

set sink0 [new Agent/TCPSink]

$ns attach-agent $leaf1 $tcp0

$ns attach-agent $leaf3 $sink0

$ns connect $tcp0 $sink0

# Simulate traffic from leaf 1 to leaf 3 via intermediate nodes and root

set ftp0 [new Application/FTP]

$ftp0 attach-agent $tcp0

$ns at 1.0 “$ftp0 start”

# Set up another TCP connection from leaf 2 to leaf 4

set tcp1 [new Agent/TCP]

set sink1 [new Agent/TCPSink]

$ns attach-agent $leaf2 $tcp1

$ns attach-agent $leaf4 $sink1

$ns connect $tcp1 $sink1

# Simulate traffic from leaf 2 to leaf 4 via intermediate nodes and root

set ftp1 [new Application/FTP]

$ftp1 attach-agent $tcp1

$ns at 2.0 “$ftp1 start”

# 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:
    • root: This is the root node at the top level (level 1).
    • int1, int2: These are the intermediate nodes (branches) that associate to the root and the leaf nodes (level 2).
    • leaf1, leaf2, leaf3, leaf4: These are the leaf nodes (end devices) at the bottom level (level 3).
  2. Links:
    • Duplex links are used to associate the root node to the intermediate nodes and the intermediate nodes to the leaf nodes. This structure forms a tree topology in which the interaction among leaves has to go via the intermediate nodes and the root node.
  3. Traffic Simulation:
    • TCP agents are used to mimic interaction among the leaf nodes. For instance, traffic flows from leaf1 to leaf3 and from leaf2 to leaf4.
    • FTP applications are used to create file transfer traffic among the leaf nodes, passing via the intermediate and root nodes.
  4. End of Simulation:
    • The simulation executes for 10 seconds that enables to monitor the interaction among leaf nodes through the intermediate nodes and root.

Post-Simulation Analysis:

  1. Trace File Analysis:
    • Open the trace file (out.tr) to monitor the packet flow in the tree topology. We can evaluate on how packets travel from the leaf nodes to the root and through intermediate nodes to the other leaves.
  2. NAM Visualization:
    • Use NAM (Network Animator) to visualize the tree topology. We will see the hierarchical structure with the root node at the top, intermediate nodes in the middle, and leaf nodes at the bottom. Traffic flows via the tree-like structure.
  3. Performance Metrics:
    • Evaluate network parameters like latency, throughput, and packet loss to evaluate how the tree topology manages traffic.

Enhancing the Simulation:

  1. Deeper Tree Structure:
    • Add more levels to the tree by establishing additional intermediate nodes among the root and the leaf nodes that generates a more complex hierarchy.
  2. Different Traffic Patterns:
    • Test with diverse traffic types like UDP or CBR (Constant Bit Rate) traffic to see how various kinds of data transmission impacts the performance of the tree topology.
  3. Link Failures:
    • To mimic the failure of links like disconnect a link among an intermediate node and the root to monitor on how the failure of critical links affects the overall network performance in a tree topology.
  4. Adding More Nodes:
    • Add more leaf nodes and intermediate nodes to upsurge the size of the tree and monitor on how performance vary with a larger network.

In this process, we had covered the details about tree topology implementation procedures and how to evaluate the tree topology outcomes across the ns2 tool. Further details regarding the tree topology will be provided in upcoming manuals.