How to Implement Trust based Routing in NS2

To implement Trust-based routing in NS2 has needs to adjust the routing protocols such as AODV, DSR, or OLSR to contain a trust metric in route decisions. Trust-based routing is usually used in Wireless Sensor Networks (WSNs) and Mobile Ad-hoc Networks (MANETs) to enhance the network reliability by choosing routes according to the trustworthiness of nodes, that can help to prevent security threats such as malicious nodes or selfish behaviour. The given below is the procedure to implement the Trust-based routing in ns2:

Steps to Implement Trust-Based Routing in NS2

  1. Set up NS2 Environment

Make sure that NS2 is installed and configured. Trust-based routing usually contain to adjusting existing routing protocols to involve a trust metric in route selection.

  1. Modify the AODV Routing Protocol

For this instance, we will adjust the AODV (Ad-hoc On-Demand Distance Vector) routing protocol that contain a trust metric. The idea is to allocate a trust value to each node and incorporate this value into the route discovery process.

Trust Model

  • Trust Metric: Each node maintains a trust value for its neighbours. The value is between 0 (least trusted) and 1 (most trusted).
  • Route Selection: When choosing a route, the AODV protocol will selects routes that contain more trusted nodes.
  1. Create a TCL Script for Trust-based Routing

This sample demonstrates how to mimic the trust-based routing in NS2 by adjusting the routing decision process to combine the trust values.

Example TCL Script for Trust-based Routing:

# Create a new NS2 simulator

set ns [new Simulator]

# Open trace and NAM output files

set tracefile [open trust_routing.tr w]

$ns trace-all $tracefile

set namfile [open trust_routing.nam w]

$ns namtrace-all $namfile

# Define wireless network parameters

set val(chan)   Channel/WirelessChannel

set val(prop)   Propagation/TwoRayGround

set val(ant)    Antenna/OmniAntenna

set val(netif)  Phy/WirelessPhy

set val(mac)    Mac/802_11

set val(ifq)    Queue/DropTail/PriQueue

set val(ifqlen) 50

set val(ll)     LL

set val(rp)     AODV;# Use AODV with trust-based modifications

set val(x)      1000

set val(y)      1000

set val(num_nodes) 10  ;# Number of nodes

# Create topography for the network

set topo [new Topography]

$topo load_flatgrid $val(x) $val(y)

# Configure node parameters

$ns node-config -adhocRouting $val(rp) \

-llType $val(ll) \

-macType $val(mac) \

-ifqType $val(ifq) \

-ifqLen $val(ifqlen) \

-antType $val(ant) \

-propType $val(prop) \

-phyType $val(netif) \

-channelType $val(chan) \

-topoInstance $topo \

-agentTrace ON \

-routerTrace ON \

-macTrace ON

# Create nodes and set initial positions

for {set i 0} {$i < $val(num_nodes)} {incr i} {

set node($i) [$ns node]

$node($i) set X_ [expr rand() * $val(x)]

$node($i) set Y_ [expr rand() * $val(y)]

$node($i) set Z_ 0

}

# Define trust values for each node (static for simplicity)

set trust_values [list 1.0 0.8 0.5 0.9 0.7 1.0 0.6 0.4 0.9 0.3]  ;# Trust values for 10 nodes

# Function to calculate the trust of a route

proc calculate_route_trust {route_nodes} {

global trust_values

set total_trust 0

foreach node $route_nodes {

set node_id [expr $node % 10]    ;# Map node ID to trust value index

set trust_value [lindex $trust_values $node_id]

set total_trust [expr $total_trust + $trust_value]

}

return [expr $total_trust / [llength $route_nodes]]  ;# Average trust for the route

}

# Create UDP agents for communication between node(0) and node(9)

set udp0 [new Agent/UDP]

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

set null0 [new Agent/Null]

$ns attach-agent $node(9) $null0

$ns connect $udp0 $null0

# Create CBR traffic

set cbr0 [new Application/Traffic/CBR]

$cbr0 set packetSize_ 512

$cbr0 set rate_ 1Mb

$cbr0 attach-agent $udp0

# Start and stop CBR traffic

$ns at 1.0 “$cbr0 start”

$ns at 9.0 “$cbr0 stop”

# Route discovery with trust-based decision making

proc trust_based_route_discovery {src dst} {

global ns node trust_values

set possible_routes [$ns get_routes $src $dst]  ;# Get all possible routes from src to dst

set best_route {}

set best_trust -1

foreach route $possible_routes {

set route_trust [calculate_route_trust $route]

if {$route_trust > $best_trust} {

set best_trust $route_trust

set best_route $route

}

}

return $best_route

}

# Trigger trust-based route discovery for communication

set best_route [trust_based_route_discovery 0 9]

puts “Best route based on trust: $best_route”

# Schedule simulation end

$ns at 10.0 “finish”

# Define finish procedure to close trace and NAM files

proc finish {} {

global ns tracefile namfile

$ns flush-trace

close $tracefile

close $namfile

exec nam trust_routing.nam &

exit 0

}

# Run the simulation

$ns run

  1. Explanation of Key Components
  • Trust Values: Each node is allocated a trust value, ranging from 0 (least trusted) to 1 (most trusted). These values can be enthusiastically updated during the simulation according to network behaviour or predefined.
  • Trust Calculation: The function calculate_route_trust estimates the average trust for a given route by totalling the trust values of the nodes along the route and taking the average.
  • Route Discovery: The function trust_based_route_discovery priortize the best route according to the highest trust score. It compares all possible routes among the source and destination and chooses the one with the highest average trust.
  • Communication: Traffic is created among node (0) and node (9) using UDP/CBR to mimic network communication.
  1. Running the Simulation

Save the script as trust_routing.tcl and executedit in NS2 using the following command:

ns trust_routing.tcl

Once the simulation finished, we can envision the network and routing decisions using NAM:

nam trust_routing.nam

  1. Trust Update Mechanism

We can expand the simple trust model to update trust values enthusiastically based on network behaviour. For instance, if a node drops packets or delays responses, its trust value can be mimized.

Example of Dynamic Trust Update:

# Function to reduce trust based on packet drop

proc update_trust_on_packet_drop {node_id} {

global trust_values

set trust_value [lindex $trust_values $node_id]

set new_trust [expr $trust_value * 0.9]  ;# Reduce trust by 10% on packet drop

lset trust_values $node_id $new_trust

puts “Updated trust for node $node_id: $new_trust”

}

We can call this function whenever a packet drop event is discovered to enthusiastically adapt the trust values.

  1. Advanced Features for Trust-Based Routing

We can expand the trust-based routing simulation in several ways:

  • Reputation-Based Trust: Execute a reputation system in which nodes distribute trust values with each other to collaboratively build trust.
  • Malicious Node Detection: Establish malicious nodes that drop or interfere with packets, and classify them according to the trust metrics.
  • Security Protocols: Integrate trust with encryption or authentication protocols for more robust security.

In this process, we had covered the details about Trust-based routing implementation procedures and how to evaluate the Trust-based routing outcomes across the ns2 tool. Further details regarding the Trust-based routing will be provided in upcoming manuals.

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