How to Calculate Network Reliability in NS2

To calculate the Network Reliability using NS2, which can describe as the ability of the network to successfully transmit data from an origin to end without packet loss or failure. The compute of the reliability is usually based on the factors like packet delivery ratio (PDR), successful packet transmissions, error rate, and the obtainability of network nodes and links.

To estimate the network reliability within NS2, we can be used numerous metrics, which estimate the reliability and performance of the network. Given below is some general steps to compute network reliability:

Steps to Calculate Network Reliability in NS2:

  1. Packet Delivery Ratio (PDR)

Packet Delivery Ratio (PDR) is one of the most general metrics for assessing the network reliability. It is computed as the ratio of the number of effectively received packets to the total amount of sent packets.

Steps:

  1. Generate Trace File: Make certain that NS2 script is set up to generate a trace file:

set tracefile [open out.tr w]

$ns trace-all $tracefile

  1. Analyze the Trace File: The trace file logs all the send and receive events for each packet within the network. We can be used an AWK script to compute the PDR by comparing the number of packets transmitted and received.

The following is an instance AWK script to calculate the PDR:

awk ‘{

if ($1 == “+” && $4 == “tcp”) {

sent_packets++;

}

if ($1 == “r” && $4 == “tcp”) {

received_packets++;

}

} END {

if (sent_packets > 0) {

pdr = (received_packets / sent_packets) * 100;

print “Packet Delivery Ratio (PDR): ” pdr “%”;

} else {

print “No packets were sent.”;

}

}’ out.tr

This script:

    • Counts the number of TCP packets sent (+ event) and received (r event).
    • Computes the PDR as (received_packets / sent_packets) * 100.

A high PDR shows good network reliability.

  1. Packet Loss Ratio (PLR)

Packet Loss Ratio (PLR) is other metric to estimate the network reliability. It calculates the percentage of packets, which were lost during transmission.

Steps:

  1. Calculate PLR: We can use the similar trace file then we can compute the PLR as follows:

awk ‘{

if ($1 == “+” && $4 == “tcp”) {

sent_packets++;

}

if ($1 == “r” && $4 == “tcp”) {

received_packets++;

}

} END {

if (sent_packets > 0) {

packet_loss = sent_packets – received_packets;

plr = (packet_loss / sent_packets) * 100;

print “Packet Loss Ratio (PLR): ” plr “%”;

} else {

print “No packets were sent.”;

}

}’ out.tr

This script:

    • Computes the number of lost packets as sent_packets – received_packets.
    • Estimates PLR as (packet_loss / sent_packets) * 100.

Lower PLR values are show better network reliability.

  1. End-to-End Delay

Reliability can also estimate by the end-to-end delay that is the time it takes for a packet to travel from the source to the end. Although delay itself does not directly evaluate the reliability, excessive delays can show network congestion or failures, influencing overall reliability.

Steps:

  1. Calculate Average End-to-End Delay: Below is a AWK script computes the average end-to-end delay for TCP packets:

awk ‘{

if ($1 == “+” && $4 == “tcp”) {

send_time[$6] = $2;  # Store the send time based on packet ID

}

if ($1 == “r” && $4 == “tcp”) {

if (send_time[$6] != “”) {

delay = $2 – send_time[$6];

total_delay += delay;

packet_count++;

delete send_time[$6];

}

}

} END {

if (packet_count > 0) {

avg_delay = total_delay / packet_count;

print “Average End-to-End Delay: ” avg_delay ” seconds”;

} else {

print “No packets were received.”;

}

}’ out.tr

This script:

    • Monitors the send and receive times for each packet.
    • Estimates the total delay for all packets and averages it.

Lower delay values, together with high packet delivery, show more reliable network performance.

  1. Network Availability

Network availability refers to the ability of the network to maintain the links and operational nodes. If nodes or links are go down often then the network reliability reduces.

Steps:

  1. Track Node and Link Failures: If we are replicating the link or node failures in the NS2 simulation (e.g., in a wireless sensor network) then we can log when nodes are fail or when links are broken. We can be computed the obtainability rely on the uptime of the nodes or links.
  2. Calculate Node Availability: Node availability can be computed as the percentage of time nodes are operational during the simulation. It can be done by logging the time when nodes are go down and when they recover.

For example:

proc monitor_node {node_id} {

global ns

if {[$node($node_id) energy] <= 0} {

puts “Node $node_id failed at time [$ns now]”

# Calculate availability as (simulation_time – failure_time) / simulation_time

}

}

# Schedule node energy monitoring at regular intervals

for {set i 0} {$i < 10} {incr i} {

$ns at 1.0 “monitor_node $i”

}

  1. Calculate Network Availability: When we have logged the downtime and uptime of the links and nodes then we can be computed the availability as:

Availability=Total UptimeTotal Simulation Time×100\text{Availability} = \frac{\text{Total Uptime}}{\text{Total Simulation Time}} \times 100Availability=Total Simulation TimeTotal Uptime​×100

Higher availability means better network reliability.

  1. Throughput

Throughput refers to the rate at which data is effectively sent over the network. Reliable networks are normally maintain a high throughput rate.

Steps:

  1. Calculate Network Throughput: We can be estimated the throughput by adding up the amount of data effectively received by the end and dividing it by the simulation time.

Now, given below is an AWK script to calculate throughput:

awk ‘{

if ($1 == “r” && $4 == “tcp”) {

total_data += $6;  # Sum up the data size in bytes

}

} END {

simulation_time = 100.0;  # Replace with your simulation duration

throughput = total_data / simulation_time;

print “Network Throughput: ” throughput ” bytes/second”;

}’ out.tr

Higher throughput values are show better network reliability.

  1. Redundancy and Fault Tolerance

In some cases, the network reliability can enhance by utilising the redundancy and fault tolerance methods. For instance, using backup paths, additional nodes, or alternative transmission routes. In NS2, we can be replicated these mechanisms and estimate their effect on reliability by computing the packet delivery ratio, latency, and availability when a node or link fails.

As above, we had indicated the computation process that based on the factors such as packet delivery ratio (PDR), successful packet transmissions, error rate, and the obtainability of network nodes and links are helps to calculate the Network Reliability within NS2 tool. More insights will be provided in upcoming manual based on your needs.

We focus on key metrics like packet delivery ratio (PDR), successful packet transmissions, error rates, and the availability of network nodes and links for your projects. Share your project details with us, and we’ll assist you! Our team can help you calculate Network Reliability using the NS2 tool, tailored to your project ideas and topics. Let our experts take care of it for you!