How to Calculate Network Maintainability in NS2
To calculate the Network maintainability within NS2 that refers to the ability of the network to be reinstated to usual operation after the failures or issues then how easily the network can be handled and observed. It encompasses the metrics like recovery time, fault detection efficiency, and ease of configuration changes. Although NS2 does not directly deliver the tools to calculate maintainability, we can be replicated network faults and repairs, observe their impacts and calculate how rapidly and effectively the network can retrieve from the failures. Below, we give step-by-step computation process to replicate and compute it in NS2:
Steps to Simulate and Calculate Network Maintainability in NS2
- Set Up NS2 Simulation for Maintainability
To replicate network maintainability, we can be described the situations in which the nodes or links fail then observe how rapidly the network retrieves after faults are repaired. Key metrics contain fault detection time, recovery time, and reconfiguration time.
Example NS2 Script for Simulating Network Failure and Recovery
# Create NS2 simulator instance
set ns [new Simulator]
# Open trace file for logging events
set tracefile [open maintainability_trace.tr w]
$ns trace-all $tracefile
# Define network nodes
set node1 [$ns node] ;# Node 1 (client)
set node2 [$ns node] ;# Node 2 (gateway)
set node3 [$ns node] ;# Node 3 (server)
# Create duplex links between nodes
$ns duplex-link $node1 $node2 1Mb 10ms DropTail
$ns duplex-link $node2 $node3 1Mb 10ms DropTail
# Set up UDP agents to simulate traffic between nodes
set udp1 [new Agent/UDP]
$ns attach-agent $node1 $udp1
set udp2 [new Agent/UDP]
$ns attach-agent $node3 $udp2
$ns connect $udp1 $udp2
# Set up CBR traffic to simulate continuous data transmission
set cbr1 [new Application/Traffic/CBR]
$cbr1 set packetSize_ 500
$cbr1 set interval_ 0.01
$cbr1 attach-agent $udp1
# Start normal traffic
$ns at 0.5 “$cbr1 start”
# Simulate network failure at 2 seconds (disable link between node2 and node3)
$ns at 2.0 “$ns detach-agent $node2 $udp2”
# Simulate network recovery at 4 seconds (re-enable link between node2 and node3)
$ns at 4.0 “$ns attach-agent $node2 $udp2”
# Stop simulation after 6 seconds
$ns at 6.0 “finish”
proc finish {} {
global ns tracefile
$ns flush-trace
close $tracefile
exit 0
}
# Run the simulation
$ns run
Explanation:
- Node Setup: Three nodes (node1, node2, node3) are mimic a simple client-server-gateway architecture.
- Traffic Simulation: Constant Bit Rate (CBR) traffic replicates continuous data flow among the client (node1) and server (node3).
- Failure Simulation: At 2 seconds, the link among the gateway (node2) and server (node3) is deactivated, replicating a network failure.
- Recovery Simulation: At 4 seconds, the link is re-enabled, after a repair mimicking network recovery.
- Monitor Network Recovery and Maintainability
We can be observe the network’s performance before, during, and after the failure by examining the trace file to monitor how rapidly the network recovers and restarts normal operations.
- Calculate Key Maintainability Metrics
Recovery Time
After a failure is resolved, the recovery time is the time taken for the network to return to usual operation. It is calculated by the time variance among when the network is retrieves and when the failure happened.
Given below is an AWK script to compute network recovery time:
awk ‘
{
if ($1 == “d” && $2 == “2.0”) { # Detect when the failure occurs at 2 seconds
failure_time = $2;
}
if ($1 == “r” && $3 == “node3”) { # Detect when traffic is resumed at node3 after recovery
recovery_time = $2;
print “Network Recovery Time:”, recovery_time – failure_time, “seconds”;
}
}’ maintainability_trace.tr
This script identifies when the failure happens and when the network restarts the normal operations then we computes the recovery time.
Fault Detection Time
The fault detection time is the time it takes for the network or observing the system to identify a failure. In this situation, we can be assessed how rapidly traffic drops or an alert is activated after the failure happens.
The following is an AWK script to estimate fault detection time:
awk ‘
{
if ($1 == “d” && $2 == “2.0”) { # Failure at 2 seconds
failure_time = $2;
}
if ($1 == “d” && $3 == “node3”) { # Packet drop detected at node3
detection_time = $2;
print “Fault Detection Time:”, detection_time – failure_time, “seconds”;
exit; # Stop after first detection
}
}’ maintainability_trace.tr
This script evaluates the time among the failure and the first packet drop that signifying the fault detection time.
Reconfiguration Time
The reconfiguration time is the time it takes to create an essential changes (e.g., rerouting traffic or re-enabling links) to restore the network. In this situation, it is the time among when the network repair is started and when traffic resumes.
Given below is an AWK script to evaluate reconfiguration time:
awk ‘
{
if ($1 == “r” && $3 == “node3”) { # Traffic received at node3 after reconfiguration
reconfiguration_time = $2;
print “Reconfiguration Time:”, reconfiguration_time – 4.0, “seconds”; # Reconfiguration at 4 seconds
exit;
}
}’ maintainability_trace.tr
This script estimates how long it takes for traffic to restart after the link is re-enabled at 4 seconds.
Availability Metric
The availability of the network is the percentage of time, which the network is functional. It is estimated as the total time the network is functional divided by the total simulation time.
awk ‘
BEGIN {
total_simulation_time = 6.0; # Simulation runs for 6 seconds
}
{
if ($1 == “d” && $2 == “2.0”) { # Detect network failure
downtime_start = $2;
}
if ($1 == “r” && $3 == “node3”) { # Detect when traffic resumes
downtime_end = $2;
downtime = downtime_end – downtime_start;
}
}
END {
uptime = total_simulation_time – downtime;
availability = (uptime / total_simulation_time) * 100;
print “Network Availability:”, availability, “%”;
}’ maintainability_trace.tr
This script measure the obtainability of the network by subtracting the downtime from the total simulation time.
- Simulate Additional Maintainability Scenarios
- Multiple Failures: We can be replicated numerous failures and trace how successfully the network manages concurrent or dropping failures.
- Fault-Tolerant Mechanisms: Execute fault-tolerant mechanisms like rerouting or redundancy and compute their efficiency in maintaining network stability.
- Maintenance Intervals: Mimic planned maintenance intervals to monitor how simply the network can be reinstated after routine updates.
- Visualize Network Recovery Metrics
When we have computed the recovery and maintainability metrics then we can be visualized the data using tools such as Python (matplotlib) to acquire better insight into the network’s maintainability.
Example Python Plot for Network Recovery Time:
import matplotlib.pyplot as plt
# Example data for recovery time after different failures
failures = [‘Failure 1’, ‘Failure 2’, ‘Failure 3’]
recovery_times = [2.0, 1.5, 1.8] # Recovery times in seconds
plt.bar(failures, recovery_times)
plt.title(‘Network Recovery Time After Failures’)
plt.xlabel(‘Failures’)
plt.ylabel(‘Recovery Time (seconds)’)
plt.show()
Summary
To compute the network maintainability in NS2:
- Set up the simulation: Describe the situations where links or nodes fail and recover after a particular duration.
- Monitor network behaviour: Trace traffic before, during and after the failure to estimate how rapidly the network recovers.
- Calculate key metrics: We can be used the AWK scripts to compute the recovery time, fault detection time, reconfiguration time, and network availability.
- Simulate additional scenarios: Examine fault tolerance, numerous failures, and planned maintenance.
- Visualize results: We can use the Python or other tools to plot metrics like recovery time and availability.
As illustrated above, we expressed the stepwise computation procedure with some relevant example on how to simulate and compute the Network Maintainability within NS2 platform. We ready to provide more informations as required in future.
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