How to Implement Point to Multipoint Topology in ns2

To implement Point-to-Multipoint Topology in Network Simulator 2 (NS2) has includes one central node (the point) interacting with multiple nodes (the multipoints). The central node deliver the data to all other nodes, however those nodes are not directly associated to each other. This kind of topology is commonly used in scenarios such as broadcasting or multicasting, in which one node needs to interact with many others. The given below is the brief procedure to implement the point to multipoint topology in ns2:

Steps to Implement Point-to-Multipoint Topology in NS2:

  1. Set Up the Network Topology:
    • Describe one central node and several other nodes.
    • Generate duplex links from the central node to each of the other nodes that mimics a point-to-multipoint connection.
  2. Simulate Traffic Flow:
    • Create traffic from the central node to each of the other nodes.

Example of Point-to-Multipoint Topology Implementation in NS2:

Below is a sample script that demonstrates how to configure a point-to-multipoint topology with traffic flowing from the central node to multiple 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 in the point-to-multipoint topology (1 central node and 3 leaf nodes)

set central [$ns node]  ;# Central node (sender)

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

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

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

# Create duplex links from the central node to each leaf node

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

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

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

# Define TCP agents for traffic from the central node to each leaf node

# Central node sends to leaf 1

set tcp0 [new Agent/TCP]

set sink0 [new Agent/TCPSink]

$ns attach-agent $central $tcp0

$ns attach-agent $leaf1 $sink0

$ns connect $tcp0 $sink0

# Central node sends to leaf 2

set tcp1 [new Agent/TCP]

set sink1 [new Agent/TCPSink]

$ns attach-agent $central $tcp1

$ns attach-agent $leaf2 $sink1

$ns connect $tcp1 $sink1

# Central node sends to leaf 3

set tcp2 [new Agent/TCP]

set sink2 [new Agent/TCPSink]

$ns attach-agent $central $tcp2

$ns attach-agent $leaf3 $sink2

$ns connect $tcp2 $sink2

# Simulate FTP traffic from the central node to each leaf node

# Traffic from central to leaf 1

set ftp0 [new Application/FTP]

$ftp0 attach-agent $tcp0

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

# Traffic from central to leaf 2

set ftp1 [new Application/FTP]

$ftp1 attach-agent $tcp1

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

# Traffic from central to leaf 3

set ftp2 [new Application/FTP]

$ftp2 attach-agent $tcp2

$ns at 3.0 “$ftp2 start”   ;# Start traffic at 3 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:
    • Central: This node acts as the sender, distributing data to multiple other nodes.
    • leaf1, leaf2, leaf3: These are the receiving nodes, associated to the central node.
  2. Links:
    • Duplex links are generated among the central node and each of the leaf nodes. These links have a bandwidth of 1Mb, a propagation delay of 10ms, and use a DropTail queue.
  3. Traffic Simulation:
    • TCP agents are used to mimic interaction among the central node and each leaf node. For instance, central sends traffic to leaf1, leaf2, and leaf3.
    • FTP (File Transfer Protocol) applications are used to make file transfer traffic from the central node to each leaf node. The FTP traffic initiates at various times to mimic multiple simultaneous data transfers.
  4. Simulation Duration:
    • The simulation executes for 10 seconds that enables traffic to flow from the central node to all the leaf nodes.

Post-Simulation Analysis:

  1. Trace File Analysis:
    • Open the trace file (out.tr) to monitor the packet flow from the central node to each leaf node. Evaluate the parameters such as packet delivery, delay, and throughput for the point-to-multipoint communication.
  2. NAM Visualization:
    • Use NAM (Network Animator) to visualize the point-to-multipoint topology. We will see the central node associated to multiple leaf nodes, and the traffic flows from the central node to each leaf node.
  3. Performance Metrics:
    • Assess network parameters like delay, throughput, and packet loss to evaluate on how well the point-to-multipoint connection manages the traffic.

Enhancing the Simulation:

  1. Changing Traffic Type:
    • We can replace TCP with UDP or use CBR (Constant Bit Rate) rather than FTP to mimic diverse types of traffic and evaluate on how the network performs.
  2. Simulating Traffic in Both Directions:
    • Configure traffic in the reverse direction (from leaf nodes back to the central node) to mimic bidirectional communication.
  3. Multicast or Broadcast Traffic:
    • To mimic a multicast or broadcast scenario, we can discover using multicast routing protocols or mimic broadcast interaction from the central node to all leaf nodes.
  4. Varying Link Parameters:
    • Validate with diverse link metrics like bandwidth, delay, and queue type (e.g., DropTail or RED) to learn on how the network performance varies in numerous conditions.
  5. Increasing the Number of Leaf Nodes:
    • Attach more leaf nodes to the network to mimic a larger point-to-multipoint topology and monitor on how performance varies with scale.

In the entire page was successfully demonstrated the complete procedure to implement the point-to-multipoint topology that was executed using ns2 simulation tool. We plan to deliver more information regarding the point-to-multipoint topology.

For the implementation of the Point to Multipoint Topology, ns2project.com serves as an excellent resource, providing you with the latest insights and topics. Our developers are available to conduct network performance analysis for your projects.