To simulate a Point-to-Point Topology uisng NS2, which is one of the simplest network configurations in which two nodes are directly associated by a dedicated link. This configuration can be utilized to learn communication among two hosts or nodes over a dedicated path.
We will walk you through the simulation process on how to simulate a Point-to-Point Topology project in NS2:
Steps to Simulate Point-to-Point Topology Projects in NS2
- Set up NS2 Environment:
Make sure NS2 is installed and functioning on the machine. We will write a TCL script to replicate the point-to-point topology.
- Understanding Point-to-Point Topology:
- In a Point-to-Point Topology, two devices (nodes) are directly associated by a dedicated link. This kind of topology is basic and make sure that all communication occurs over this single, exclusive connection.
- Normally used to mimic direct communication among two nodes without interference from other devices.
- Create a TCL Script for Point-to-Point Topology:
Following is an instance of a simple Point-to-Point Topology simulation:
# Create a new simulator instance
set ns [new Simulator]
# Open a NAM trace file for visualization
set nf [open out.nam w]
$ns namtrace-all $nf
# Create two nodes (point-to-point connection)
set n0 [$ns node]
set n1 [$ns node]
# Create a duplex link between the two nodes (10Mb bandwidth, 10ms delay, DropTail queue)
$ns duplex-link $n0 $n1 10Mb 10ms DropTail
# Create a UDP agent and attach it to node n0
set udp0 [new Agent/UDP]
$ns attach-agent $n0 $udp0
# Create a Null agent (sink) and attach it to node n1
set null0 [new Agent/Null]
$ns attach-agent $n1 $null0
# Connect the UDP agent at n0 to the Null agent at n1
$ns connect $udp0 $null0
# Create a Constant Bit Rate (CBR) traffic source and attach it to the UDP agent
set cbr0 [new Application/Traffic/CBR]
$cbr0 attach-agent $udp0
$cbr0 set packetSize_ 512 ;# Packet size of 512 bytes
$cbr0 set rate_ 100Kb ;# Data rate of 100Kb
# Schedule the CBR traffic to start and stop
$ns at 1.0 “$cbr0 start” ;# Start traffic at 1 second
$ns at 5.0 “$cbr0 stop” ;# Stop traffic at 5 seconds
# Define when to end the simulation
$ns at 6.0 “finish”
proc finish {} {
global ns nf
$ns flush-trace
close $nf
exec nam out.nam &
exit 0
}
# Run the simulation
$ns run
- Explanation of the Code:
- Nodes: Two nodes are made (n0 and n1). These nodes are signifying the two ends of the point-to-point connection.
- Link: A duplex link relates the two nodes. The link is set up with 10Mb bandwidth, 10ms delay, and a DropTail queue management system.
- UDP Traffic: A UDP agent is made and connected to node n0. A Null agent (data sink) is connected to node n1.
- Traffic Generator (CBR): A Constant Bit Rate (CBR) traffic generator is made to replicate the data flow over the UDP connection. Traffic begins at 1.0 seconds and ends at 5.0 seconds.
- NAM Trace: The simulation will make a .nam file (out.nam) that can be envisioned utlising the Network Animator (NAM) tool.
- Run the Simulation:
- We need to save the above script within a file called point_to_point.tcl.
- Open a terminal and navigate to the folder where your script is saved.
- We can run the simulation by executing:
ns point_to_point.tcl
- The simulation will make an output file called out.nam. We can envision the topology and the traffic using the NAM tool.
- Visualization in NAM:
- After the simulation executes then we can open the Network Animator (NAM) tool to visualize the point-to-point topology and monitor the data flow among the two nodes.
- Customization and Enhancements:
- TCP Traffic: We can change the script to utilize TCP traffic rather than UDP. For instance:
set tcp0 [new Agent/TCP]
$ns attach-agent $n0 $tcp0
set sink [new Agent/TCPSink]
$ns attach-agent $n1 $sink
$ns connect $tcp0 $sink
- Different Bandwidth/Delay: We can test with distinct link metrics such as bandwidth and delay. For instance, we can maximize the bandwidth to 100Mb or set a delay of 20ms.
- Multiple Flows: We can insert more traffic flows to replicate diverse communication scenarios, like using a combination of TCP and UDP traffic.
- Performance Metrics: We can include tracing to assess performance parameters such as packet loss, delay, or throughput. We can utilize the following commands to allow traces:
set tracefile [open trace.tr w]
$ns trace-all $tracefile
- Performance Analysis:
We can examine the performance of the point-to-point link by:
- Calculating throughput
- Examining packet loss
- Monitoring the round-trip delay (for TCP)
We were effectively established the Point to Point Topology projects that were simulated using the above procedure within NS2 tool. If you require further details and related instances on this subject, we will be shared.
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