How to Implement Network Traffic Aware Routing in NS2
To implement Network Traffic-Aware Routing in NS2 has needs to model a routing protocol that enthusiastically chooses the paths according current traffic conditions, like congestion or bandwidth availability. Contrasting traditional routing protocols, traffic-aware routing continuously monitors the network and adjusts routing decisions to enhance performance.
Here’s a step-by-step guide on how to implement Network Traffic-Aware Routing in NS2:
Step-by-Step Guide to Implement Network Traffic-Aware Routing in NS2
- Set Up the Basic Network Topology:
- Initially generate a simple network of nodes in which routing will be performed according to traffic conditions.
- Each node should be capable of monitoring network traffic such as queue sizes, bandwidth, or packet loss.
Example OTcl script for a basic network setup:
set ns [new Simulator]
set nf [open out.tr w]
$ns trace-all $nf
set namfile [open out.nam w]
$ns namtrace-all $namfile
# Define network nodes
set node0 [$ns node] ;# Source Node
set node1 [$ns node] ;# Intermediate Node
set node2 [$ns node] ;# Intermediate Node
set node3 [$ns node] ;# Destination Node
# Create links between nodes
$ns duplex-link $node0 $node1 1Mb 10ms DropTail
$ns duplex-link $node0 $node2 1Mb 10ms DropTail
$ns duplex-link $node1 $node3 1Mb 10ms DropTail
$ns duplex-link $node2 $node3 1Mb 10ms DropTail
# Define normal traffic between node0 and node3
set udp [new Agent/UDP]
set null [new Agent/Null]
$ns attach-agent $node0 $udp
$ns attach-agent $node3 $null
$ns connect $udp $null
set cbr [new Application/Traffic/CBR]
$cbr attach-agent $udp
$cbr set packetSize_ 512
$cbr set rate_ 1Mb
# Start traffic
$ns at 1.0 “$cbr start”
$ns at 5.0 “$cbr stop”
# Run simulation
$ns at 6.0 “finish”
proc finish {} {
global ns nf namfile
$ns flush-trace
close $nf
close $namfile
exec nam out.nam &
exit 0
}
$ns run
- This setup generates a network with four nodes. Traffic flows from node0 (source) to node3 (destination) through two possible paths: via node1 or node2.
- Define Traffic Monitoring Logic:
- For traffic-aware routing, each node tracks traffic-related parameters such as queue size, packet drop rate, or bandwidth utilization. This information will demonstrate the routing decisions.
Example OTcl script to monitor queue size:
proc monitor_queue_size {node} {
global ns
set queue_size [$node ifq-length]
puts “Node $node has queue size: $queue_size”
return $queue_size
}
# Periodically check queue size at nodes
$ns at 2.0 “monitor_queue_size $node1”
$ns at 2.5 “monitor_queue_size $node2”
- In this sample, the monitor_queue_size function tracks the queue size at each intermediate node (node1 and node2). We can expand this to observe other traffic-related parameters.
- Implement Traffic-Aware Routing Logic:
- According to the monitored traffic, the routing protocol chooses the best path. For example, the path with the least congestion (smallest queue size or highest available bandwidth) could be designated.
Example OTcl script for traffic-aware routing:
# Decision logic for choosing the path with the least congestion
proc choose_best_path {queue_size1 queue_size2} {
if { $queue_size1 < $queue_size2 } {
return “path1”
} else {
return “path2”
}
}
# Handle traffic and make routing decision
proc route_traffic_based_on_queue {node0 node1 node2 node3} {
set queue_size1 [monitor_queue_size $node1]
set queue_size2 [monitor_queue_size $node2]
set best_path [choose_best_path $queue_size1 $queue_size2]
if { $best_path == “path1” } {
# Route through node1
puts “Routing traffic via node1 (less congested)”
$ns connect $node0 $node1
$ns connect $node1 $node3
} else {
# Route through node2
puts “Routing traffic via node2 (less congested)”
$ns connect $node0 $node2
$ns connect $node2 $node3
}
}
# Periodically check for the best path and route traffic
$ns at 2.0 “route_traffic_based_on_queue $node0 $node1 $node2 $node3”
- The choose_best_path function chooses the path according to the queue size of intermediate nodes. We can adjust this logic to contain other traffic parameters such as bandwidth or packet drop rate.
- Simulate Dynamic Routing Adjustments:
- To mimic traffic-aware routing, that needs to validate traffic conditions intermittently and adapt routing decisions dynamically.
Example of periodic routing adjustments:
# Check and adjust the routing path every second
proc periodic_routing_adjustment {} {
route_traffic_based_on_queue $node0 $node1 $node2 $node3
$ns at [expr [clock seconds] + 1] “periodic_routing_adjustment”
}
# Start the periodic routing adjustment
$ns at 1.0 “periodic_routing_adjustment”
- This technique makes sure that the network continually adapts the routing paths based on current traffic conditions.
- Add More Complex Traffic Conditions (Optional):
- To fully validate the traffic-aware routing protocol, we can establish more traffic flows or changing the traffic rates enthusiastically during the simulation.
Example of adding more traffic:
# Add a second traffic flow between node1 and node3
set udp2 [new Agent/UDP]
$ns attach-agent $node1 $udp2
$ns connect $udp2 $null
set cbr2 [new Application/Traffic/CBR]
$cbr2 attach-agent $udp2
$cbr2 set packetSize_ 512
$cbr2 set rate_ 500Kb
# Start the second flow at 2.0 seconds
$ns at 2.0 “$cbr2 start”
$ns at 4.0 “$cbr2 stop”
- This replicate another flow among node1 and node3 that establishes more traffic, that leads potential congestion at node1.
- Run the Simulation and Analyse Results:
- Execute the simulation to see how the traffic-aware routing adapts the paths based on traffic conditions.
ns your_script.tcl
- Use trace files created by NS2 to evaluate the characteristics of the traffic-aware routing protocol. The parameters to monitor that involve path selection frequency, packet loss, throughput, and end-to-end delay.
- Analyse Traffic-Aware Routing Metrics:
- Path Selection Frequency: Track how usually each path (through node1 or node2) is choosen based on traffic conditions.
- End-to-End Delay: Assess the time it takes for packets to travel from the source to the destination, comparing the different paths.
- Packet Loss: Observe packet loss rates to assess either on routing decisions are efficiently minimizing congestion.
Example AWK script to analyse path selection:
awk ‘{ if ($1 == “s” && $5 == “node1”) path1++; if ($1 == “s” && $5 == “node2”) path2++; }
END { print “Path1 selected:”, path1, “times”; print “Path2 selected:”, path2, “times”; }’ out.tr
- This script counts how usually packets are transmitted via node1 versus node2 and that supports to assess on how the traffic-aware routing protocol is making decisions.
- Visualize Traffic-Aware Routing in NAM:
- Use NAM (Network Animator) to envision how the routing decisions are made according to the traffic conditions.
nam out.nam
- In NAM, we can monitor on how the packets are transmitted via diverse paths (node1 or node2) and how traffic congestion impacts the path selection.
Summary:
To execute Network Traffic-Aware Routing in NS2:
- Set up a network topology with multiple paths among source and destination nodes.
- Monitor traffic conditions (e.g., queue size, bandwidth) at each intermediate node.
- Implement a routing decision algorithm that enthusiastically chooses the best path according to the current traffic conditions.
- Periodically adjust the routing path to respond to variations in network traffic.
- Run the simulation and analyse key metrics, like path selection frequency, end-to-end delay, and packet loss.
- Visualize the simulation in NAM to see how routing decisions change in real time according to traffic conditions.
In the presented manual will demonstrated the implementation process that supports to implement the Network Traffic-Aware Routing and measure their performance in NS2 tool. More details will be offered on this Network Traffic-Aware Routing in upcoming manual.
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