How to Implement Network Traffic Balancing in NS2

To implement Network Traffic Balancing in NS2 have a series of steps that follows and denotes to allocating network traffic evenly through available paths or links to prevent congestion and enhance the use of network resources. Traffic balancing can be executed using numerous approaches like an equal-cost multipath (ECMP) routing, load-aware routing, or round-robin distribution. The goal is to make sure that no single path becomes overloaded since other paths remain underutilized.

Here’s a step-by-step guide on how to implement Network Traffic Balancing in NS2:

Step-by-Step Guide to Implement Network Traffic Balancing in NS2

Set Up the Basic Network Topology:

Initiate; generate a network topology in which multiple paths are available among the source and destination nodes. This will enable traffic to be split via different links.

Example OTcl script to set up a basic network topology with multiple paths:

set ns [new Simulator]

set nf [open out.tr w]

$ns trace-all $nf

set namfile [open out.nam w]

$ns namtrace-all $namfile

# Create nodes

set node0 [$ns node] ;# Source node

set node1 [$ns node] ;# Intermediate node 1 (Path 1)

set node2 [$ns node] ;# Intermediate node 2 (Path 2)

set node3 [$ns node] ;# Destination node

# Create links between the nodes to form two paths

$ns duplex-link $node0 $node1 1Mb 10ms DropTail

$ns duplex-link $node1 $node3 1Mb 10ms DropTail

$ns duplex-link $node0 $node2 1Mb 10ms DropTail

$ns duplex-link $node2 $node3 1Mb 10ms DropTail

# Define UDP communication 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 at 1.0 seconds and stop at 5.0 seconds

$ns at 1.0 “$cbr start”

$ns at 5.0 “$cbr stop”

# Run the 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 topology delivers two paths among the source (node0) and the destination (node3), that enable traffic to be split and balanced among the paths.

Implement Traffic Balancing Logic:

To execute traffic balancing, traffic will need to be dispersed through both paths (node1 -> node3 and node2 -> node3). This can be completed in several ways, like round-robin, load-based distribution, or equal-cost multipath (ECMP) routing.

Example: Round-Robin Traffic Balancing

# Initialize a variable to track which path to use

set path_toggle 0

# Function to alternate between paths

proc route_traffic_round_robin {udp node0 node1 node2 node3 path_toggle} {

if { $path_toggle == 0 } {

puts “Routing traffic via Path 1 (node0 -> node1 -> node3)”

$ns connect $node0 $node1

$ns connect $node1 $node3

set path_toggle 1 ;# Switch to the other path next time

} else {

puts “Routing traffic via Path 2 (node0 -> node2 -> node3)”

$ns connect $node0 $node2

$ns connect $node2 $node3

set path_toggle 0 ;# Switch back to the first path

}

# Periodically call the traffic routing function to balance traffic

$ns at 1.0 “route_traffic_round_robin $udp $node0 $node1 $node2 $node3 $path_toggle”

$ns at 2.0 “route_traffic_round_robin $udp $node0 $node1 $node2 $node3 $path_toggle”

In this round-robin approach, traffic is alternated among two paths at regular intervals, make sure balanced distribution.

Simulate Load-Aware Traffic Balancing (Optional):

In a load-aware traffic balancing mechanism, the traffic is transmitted based on the current load on each path. The path with the lowest traffic load or smallest queue size is selected for the next packet.

Example of load-aware traffic balancing:

# Function to check queue size at intermediate nodes and route traffic

proc route_traffic_based_on_load {udp node0 node1 node2 node3} {

set queue_size1 [$node1 ifq-length]

set queue_size2 [$node2 ifq-length]

# Compare queue sizes and select the path with less traffic

if { $queue_size1 < $queue_size2 } {

puts “Routing traffic via Path 1 (less congested)”

$ns connect $node0 $node1

$ns connect $node1 $node3

} else {

puts “Routing traffic via Path 2 (less congested)”

$ns connect $node0 $node2

$ns connect $node2 $node3

}

# Periodically check the load and adjust the routing

$ns at 1.0 “route_traffic_based_on_load $udp $node0 $node1 $node2 $node3”

$ns at 2.0 “route_traffic_based_on_load $udp $node0 $node1 $node2 $node3”

This techniques uses real-time queue sizes to select that path is less congested and directs traffic consequently.

Implement Equal-Cost Multipath (ECMP) Routing (Optional):

ECMP routing allocates traffic via multiple paths that have the same cost such as bandwidth, delay. In NS2, we can mimic an ECMP by splitting the traffic evenly through the available paths.

Example of ECMP routing:

# Split traffic evenly across the two paths

proc route_traffic_ecmp {udp node0 node1 node2 node3} {

global ns

set packet_count 0

# Function to alternate paths every other packet

proc send_packet_ecmp {udp node0 node1 node2 node3 packet_count} {

if { $packet_count % 2 == 0 } {

# Send packet via Path 1

puts “Routing packet via Path 1 (node0 -> node1 -> node3)”

$ns connect $node0 $node1

$ns connect $node1 $node3

} else {

# Send packet via Path 2

puts “Routing packet via Path 2 (node0 -> node2 -> node3)”

$ns connect $node0 $node2

$ns connect $node2 $node3

}

incr packet_count

}

# Periodically send packets and alternate paths

$ns at 1.0 “send_packet_ecmp $udp $node0 $node1 $node2 $node3 $packet_count”

$ns at 1.5 “send_packet_ecmp $udp $node0 $node1 $node2 $node3 $packet_count”

$ns at 2.0 “send_packet_ecmp $udp $node0 $node1 $node2 $node3 $packet_count”

}

# Call ECMP routing to split traffic

$ns at 1.0 “route_traffic_ecmp $udp $node0 $node1 $node2 $node3”

ECMP alternates packets among both paths, allocating the load evenly.

Run the Simulation and Analyse Results:

After configuring traffic balancing logic, execute the simulation to monitor on how the traffic is shared via the different paths.

ns your_script.tcl

We evaluate the trace files created by NS2 to validate either traffic balancing is efficiently distributing traffic among the available paths.

Analyse Traffic Balancing Metrics:

Path Utilization: Track how many packets were sent over each path to measure on either on traffic was dispersed evenly.
End-to-End Delay: Assess the latency experienced by packets on diverse paths to regulate if traffic balancing is minimizing congestion.
Packet Loss: Validate if balancing traffic via multiple paths minimized packet loss compared to using a single path.

Example AWK script to analyze path utilization:

awk ‘{if ($1 == “s” && $5 == “node1”) path1_count++; if ($1 == “s” && $5 == “node2”) path2_count++;}

END { print “Packets sent via Path 1:”, path1_count; print “Packets sent via Path 2:”, path2_count; }’ out.tr

This script counts the number of packets sent via each path, enable to validate the efficiency of traffic balancing.

Visualize Traffic Balancing in NAM:

Use NAM (Network Animator) to envision how traffic is transmitted via the diverse paths and how traffic balancing is achieved in real-time.

nam out.nam

In NAM, we can monitor on how the traffic is allotted via both paths (node0 -> node1 -> node3 and node0 -> node2 -> node3), and see how traffic patterns change over time.

Summary:

To execute Network Traffic Balancing in NS2:

Set up a basic network topology with multiple paths among the source and destination nodes.
Implement traffic balancing logic, like round-robin, load-aware routing, or ECMP, to allocate traffic via the paths.
Simulate traffic balancing by intermittently adapting the routing paths according to the selected techniques.
Run the simulation and evaluate parameters like path utilization, end-to-end delay, and packet loss.
Visualize the traffic balancing in NAM to monitor how traffic is disseminated in real-time.

From this page, we clearly understood the examples that were relates to the Network Traffic Balancing that were execute in the tool of ns2. If you need more information regarding the Network Traffic Balancing we will provide that too.

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