How to Implement Network Rapid Fault Handling in NS2

To implement Rapid Fault Handling in NS2 has needs to replicate the fault detection and recovery mechanisms to safeguards the network’s flexibility to node or link failures. In this simulation, the main goal is to design on how a network detects faults and reroutes traffic enthusiastically to maintain connectivity. We provide you with top-notch thesis ideas and topics customized to your interests. For effective implementation results in Network Rapid Fault Handling using the NS2 tool, you can reach out to the ns2project.com team. The below is the implementation guide to implementing rapid fault handling in NS2:

Step-by-Step Implementation:

  1. Set up the Simulation Environment

Initially we describe a network topology with nodes and links that denotes a simple network. For fault handling, we will replicate on how the network behaves when a link or node fails and how traffic is rerouted.

Example TCL Script for Basic Setup:

# Create a simulator instance

set ns [new Simulator]

# Set link parameters

set bw 1Mb         ;# Bandwidth for each link

set delay 10ms     ;# Delay for each link

# Create nodes (representing network devices)

set node1 [$ns node]

set node2 [$ns node]

set node3 [$ns node]

set node4 [$ns node]

# Create links between nodes

$ns duplex-link $node1 $node2 $bw $delay DropTail

$ns duplex-link $node2 $node3 $bw $delay DropTail

$ns duplex-link $node3 $node4 $bw $delay DropTail

$ns duplex-link $node1 $node4 $bw $delay DropTail

This generates a simple topology in which nodes are associated in a partial mesh. If a link fails, the traffic should be retransmitted via other available links.

  1. Configure Traffic Sources

We now configure the traffic generators and attach them to the nodes to replicate data transmission. For fault handling, we will want to observe on how traffic behaves when a failure occurs.

Example of Creating Traffic between Nodes:

# Create UDP agent for traffic from node1 to node4

set udp1 [new Agent/UDP]

$ns attach-agent $node1 $udp1

# Create a traffic generator (CBR) to simulate traffic from node1 to node4

set cbr1 [new Application/Traffic/CBR]

$cbr1 set packet_size_ 512      ;# Packet size in bytes

$cbr1 set rate_ 1Mb             ;# Traffic rate

$cbr1 attach-agent $udp1

# Create a UDP sink at node4

set null1 [new Agent/Null]

$ns attach-agent $node4 $null1

# Connect the traffic from node1 to node4

$ns connect $udp1 $null1

# Start and stop the traffic

$ns at 1.0 “$cbr1 start”

$ns at 20.0 “$cbr1 stop”

This configuration routed the traffic from node1 to node4. We will establish faults later in the link among node2 and node3 and observe how the traffic is rerouted.

  1. Introduce Faults in the Network

Next, replicate a fault by bringing down one of the links in the middle of the simulations. This denotes a link or node failure that disturbs communication.

Example of Introducing a Link Failure:

# Introduce a link failure between node2 and node3 at time 5.0 seconds

$ns rtmodel-at 5.0 down $node2 $node3

# Restore the link between node2 and node3 after 10 seconds (optional)

$ns rtmodel-at 15.0 up $node2 $node3

In this scenario, the link among node2 and node3 goes down at 5 seconds, and it is restored at 15 seconds (optional). During the downtime, traffic will need to be retransmitted via the remaining links in the network.

  1. Configure a Dynamic Routing Protocol for Fault Handling

To allow rapid fault handling, use a dynamic routing protocol like AODV (Ad hoc On-Demand Distance Vector) or DSR (Dynamic Source Routing). These protocols will systematically retransmit traffic when a fault occurs by discovering alternative paths.

Example of Using AODV Routing:

# Enable AODV as the routing protocol for the simulation

set val(rp) AODV

# Attach the routing protocol to all nodes

for {set i 1} {$i <= 4} {incr i} {

$ns at 0.0 “$node$i set ragent [new Agent/DSR]”

}

AODV will enthusiastically discover new paths when a link goes down; make sure that traffic is rerouted to maintain connectivity.

  1. Monitor and Trace the Simulation

To permit tracing to monitor on how the traffic is managed during the link failure and after recovery. The trace file will capture events like packet transmissions, losses, and delays, permits to measure the effects of faults.

Enable Trace Files:

# Enable tracing for the simulation

set tracefile [open “fault_handling_trace.tr” w]

$ns trace-all $tracefile

# Define a finish procedure to end the simulation and close the trace file

proc finish {} {

global ns tracefile

$ns flush-trace

close $tracefile

exit 0

}

# Set the simulation end time

$ns at 30.0 “finish”

The trace file will record all network events, enable them to measure how traffic is retransmitted and managed after a fault.

  1. Run the Simulation

Execute the simulation to monitor on how traffic behaves before, during, and after the fault.

# Run the simulation

$ns run

  1. Post-Simulation Analysis

Once the simulation is done, evaluate the trace file to monitor on how the network managed the fault. Specifically, we can validate:

  • Packet Delivery Ratio (PDR): The percentage of successfully delivered packets before, during, and after the fault.
  • End-to-End Delay: How much delay increased during the fault as the network rerouted traffic.
  • Routing Overhead: The number of routing control messages created during the fault recovery process.

Example Complete TCL Script for Rapid Fault Handling in NS2

# Create a simulator instance

set ns [new Simulator]

# Set link parameters

set bw 1Mb

set delay 10ms

# Create nodes (representing network devices)

set node1 [$ns node]

set node2 [$ns node]

set node3 [$ns node]

set node4 [$ns node]

# Create links between nodes

$ns duplex-link $node1 $node2 $bw $delay DropTail

$ns duplex-link $node2 $node3 $bw $delay DropTail

$ns duplex-link $node3 $node4 $bw $delay DropTail

$ns duplex-link $node1 $node4 $bw $delay DropTail

# Enable AODV as the routing protocol

set val(rp) AODV

for {set i 1} {$i <= 4} {incr i} {

$ns at 0.0 “$node$i set ragent [new Agent/AODV]”

}

# Create UDP agent for traffic from node1 to node4

set udp1 [new Agent/UDP]

$ns attach-agent $node1 $udp1

# Create a CBR traffic generator for traffic from node1 to node4

set cbr1 [new Application/Traffic/CBR]

$cbr1 set packet_size_ 512

$cbr1 set rate_ 1Mb

$cbr1 attach-agent $udp1

# Create a UDP sink at node4

set null1 [new Agent/Null]

$ns attach-agent $node4 $null1

# Connect the traffic from node1 to node4

$ns connect $udp1 $null1

# Start and stop the traffic

$ns at 1.0 “$cbr1 start”

$ns at 20.0 “$cbr1 stop”

# Introduce a link failure between node2 and node3 at time 5.0 seconds

$ns rtmodel-at 5.0 down $node2 $node3

# Restore the link between node2 and node3 at 15.0 seconds

$ns rtmodel-at 15.0 up $node2 $node3

# Enable tracing

set tracefile [open “fault_handling_trace.tr” w]

$ns trace-all $tracefile

# End simulation

$ns at 30.0 “finish”

proc finish {} {

global ns tracefile

$ns flush-trace

close $tracefile

exit 0

}

# Run the simulation

$ns run

In the demonstration we had successfully executed the Rapid Fault Handling in ns2 simulation tool that efficiently detect the faults and retransmit the traffic to sustain the connectivity. We will also deliver the additional details regarding the Rapid Fault Handling.