How to Calculate Network Download rate in NS2

To calculate the Network Download Rate using NS2 simulation environment that refers to the rate at which data is effectively received (downloaded) at the end node. It is normally stated in bits per second (bps) or bytes per second (Bps). This metric supports to calculate the performance of a network such as how rapidly it can be received the data from an origin. We deliver the simplified procedure to compute the network download rate within NS2:

Steps to Calculate Network Download Rate in NS2

To estimate the download rate (or throughput) in NS2, we require to:

  1. Replicate data transmission among the source and destination nodes.
  2. Capture the packet reception events within the trace file.
  3. Compute the amount of data received at the end node across a particular period of time.
  4. Change the received data into bits or bytes then divide by the total simulation time to estimate the download rate.
  1. Set Up the NS2 Simulation:

Initially, we want to make a simple simulation in which a source node transmits the data (e.g., a file or stream) to an end node. In this instance, we will be replicated a UDP connection sending CBR (Constant Bit Rate) traffic to denote a download.

Example TCL Script for Data Transmission:

# Create the simulator

set ns [new Simulator]

# Define the topology with two nodes: source and destination

set node_(0) [$ns node]

set node_(1) [$ns node]

# Create a duplex link between the nodes (1 Mbps bandwidth, 10ms delay)

$ns duplex-link $node_(0) $node_(1) 1Mb 10ms DropTail

# Attach UDP agents to nodes for sending and receiving data

set udp0 [new Agent/UDP]

set sink [new Agent/Null]

$ns attach-agent $node_(0) $udp0

$ns attach-agent $node_(1) $sink

$ns connect $udp0 $sink

# Set up CBR traffic on the UDP agent

set cbr0 [new Application/Traffic/CBR]

$cbr0 attach-agent $udp0

$cbr0 set packetSize_ 512        ;# Packet size in bytes

$cbr0 set rate_ 1Mb              ;# Transmission rate

# Start and stop the traffic

$ns at 1.0 “$cbr0 start”

$ns at 10.0 “$cbr0 stop”

# Enable tracing to capture packet reception

set tracefile [open out.tr w]

$ns trace-all $tracefile

# End the simulation after 12 seconds

proc finish {} {

global ns tracefile

$ns flush-trace

close $tracefile

exit 0

}

# End simulation at 12 seconds

$ns at 12.0 “finish”

In this simulation:

  • A source node transmits 512-byte packets at a rate of 1 Mbps over a link including 1 Mbps bandwidth and 10 ms delay.
  • The end node gets these packets, and the rate at which it downloads data can compute from the trace file.
  1. Trace File Overview:

After running the simulation the simulation platform NS2 generates a trace file (out.tr), which records the events such as packet transmissions and receptions. The reception events can use to assess the amount of data received by the end node and the time it takes to receive this data.

Example Trace File Entries:

r 2.000000000 _1_ AGT  — 512 cbr 0 0.0 1.0 1.0

r 3.000000000 _1_ AGT  — 512 cbr 1 0.0 2.0 2.0

r 4.000000000 _1_ AGT  — 512 cbr 2 0.0 3.0 3.0

  • r: Packet reception event.
  • 2.000000000: Time of reception in seconds.
  • _1_: Destination node (where packets are received).
  • 512: Packet size in bytes.
  • cbr: Constant Bit Rate traffic type.
  1. Calculate Download Rate:

The download rate (in bits per second) is computed as the total amount of data received divided by the total time across which the data was received.

Download Rate (bps)=Total Data Received (in bits)Total Time (in seconds)\text{Download Rate (bps)} = \frac{\text{Total Data Received (in bits)}}{\text{Total Time (in seconds)}}Download Rate (bps)=Total Time (in seconds)Total Data Received (in bits)​

  1. AWK Script to Calculate Download Rate:

We can be used an AWK script to estimate the download rate by adding the received packet sizes and dividing by the total time.

AWK Script to Calculate Download Rate:

BEGIN {

received_data = 0;

start_time = 1.0;  # Start time of the download (in seconds)

end_time = 10.0;   # End time of the download (in seconds)

}

# Process received packets at the destination (_1_)

$1 == “r” && $4 == “_1_” && $7 == “cbr” {

received_data += $8 * 8;  # Convert packet size from bytes to bits

}

END {

duration = end_time – start_time;

download_rate = received_data / duration;  # Download rate in bits per second (bps)

print “Total Data Received (bits): ” received_data;

print “Download Rate (bps): ” download_rate;

}

  • This script computes the total received data in bits and then computes the download rate in bits per second (bps).
  • $8 denotes the size of the packet in bytes that is multiplied by 8 to change it into bits.
  1. Running the AWK Script:

We can be saved the AWK script as download_rate.awk, then we run it on the trace file generated by NS2:

awk -f download_rate.awk out.tr

  1. Interpreting the Results:

The script will result the total data received in bits then the download rate in bits per second (bps).

Example output:

Total Data Received (bits): 40960

Download Rate (bps): 512000

This shows that 40960 bits of data were received in the course of the simulation then the download rate was 512 kbps.

  1. Conclusion:

To compute the network download rate in NS2:

  1. Configure the simulation with a source node sending data to an end node.
  2. Permit tracing to capture packet receptions at the end node.
  3. Calculates the trace file using an AWK script to add the received data and estimate the download rate over a particular time period.
  4. The outcomes is the download rate in bits per second (bps) or bytes per second (Bps), based on the unit we prefer.

As demonstrated above, we distributed the brief technique to calculate the Network Download Rate using AWK scripts within NS2 simulation environment. Also we will provide additional informations regarding this topic in various tools.

If you have a Network Download rate project in NS2, reach out to us. We will deliver excellent results. Send us your parameter details, and we will help you with performance analysis.