How to Implement Network QoS Attainment in NS2

To implement Network Quality of Service (QoS) attainment in NS2 has several types to setup to the network to maintain the QoS mechanisms and this includes to handles the traffic types, selecting the particular flows, and enhancing the network parameters to make sure performance guarantees like bandwidth, latency, jitter, and packet loss.

We will serve as your reliable partner in the implementation of Network QoS attainment using the NS2 tool, providing you with expert guidance throughout the process.

The given below is the detailed procedure to implement the network QoS attainment in ns2:

Key QoS Mechanisms in NS2:

  1. Traffic Differentiation: Allocate diverse kinds of traffic likeTCP, UDP, CBR to separate classes, giving significance to high-priority traffic.
  2. Bandwidth Allocation: Allocate diverse bandwidths to traffic types.
  3. Queuing Mechanisms: Use queuing disciplines such as Weighted Fair Queuing (WFQ) or Deficit Round Robin (DRR) to handle packet scheduling.
  4. Packet Dropping: Execute policies such as RED (Random Early Detection) for congestion control.

Steps to Implement Network QoS in NS2

  1. Install NS2

Ensure that NS2 installed on the system.

  1. Create a TCL Script for QoS Implementation

Below is an example script that executes simple QoS using different traffic sources and queuing disciplines.

Example: Implementing QoS with Different Traffic Flows

# Define simulator

set ns [new Simulator]

# Define trace and nam files

set tracefile [open out.tr w]

set namfile [open out.nam w]

$ns trace-all $tracefile

$ns namtrace-all $namfile

# Define a ‘finish’ procedure

proc finish {} {

global ns tracefile namfile

$ns flush-trace

close $tracefile

close $namfile

exec nam out.nam &

exit 0

}

# Create nodes

set n0 [$ns node]

set n1 [$ns node]

set n2 [$ns node]

set n3 [$ns node]

# Create duplex links between nodes with different bandwidth and delay settings

$ns duplex-link $n0 $n1 2Mb 10ms DropTail

$ns duplex-link $n1 $n2 1Mb 50ms RED

$ns duplex-link $n2 $n3 1Mb 10ms DropTail

# Create TCP traffic (High Priority Traffic)

set tcp1 [new Agent/TCP]

set sink1 [new Agent/TCPSink]

$ns attach-agent $n0 $tcp1

$ns attach-agent $n3 $sink1

$ns connect $tcp1 $sink1

# Create UDP traffic (Low Priority Traffic)

set udp1 [new Agent/UDP]

set null1 [new Agent/Null]

$ns attach-agent $n1 $udp1

$ns attach-agent $n2 $null1

$ns connect $udp1 $null1

# Add FTP traffic over TCP

set ftp1 [new Application/FTP]

$ftp1 attach-agent $tcp1

$ftp1 start 1.0

$ftp1 stop 4.0

# Add CBR traffic over UDP

set cbr1 [new Application/Traffic/CBR]

$cbr1 attach-agent $udp1

$cbr1 set packetSize_ 1000

$cbr1 set rate_ 0.5Mb

$cbr1 start 1.5

$cbr1 stop 4.5

# Define Queue Management and QoS parameters (e.g., RED for congestion control)

$ns queue-limit $n1 $n2 20  ;# Limiting queue size

$ns queue-limit $n2 $n3 30  ;# Limiting queue size

# Define the simulation end time

$ns at 5.0 “finish”

# Run the simulation

$ns run

  1. Explanation of the QoS Implementation
  • TCP and UDP Traffic: The sample contains both TCP (FTP) and UDP (CBR) traffic to mimic diverse traffic types. TCP is deliberated higher priority, while UDP uses lower priority.
  • Links with Different Bandwidth and Delay: Different links have different bandwidth and latency values to mimic changing network conditions. The link among n1 and n2 is configured with RED for congestion control that supports maintain QoS in high traffic.
  • Queue Management: The queue-limit command limits the queue size, and RED (Random Early Detection) is implemented to avoid congestion by dropping packets before the queue overflows.
  • CBR and FTP Traffic: FTP is sends through TCP and uses more bandwidth, since CBR (Constant Bit Rate) is used for UDP with a fixed rate.
  1. Advanced QoS Mechanisms

To enhance QoS further, we can use the following approaches:

4.1 Weighted Fair Queuing (WFQ)

  • WFQ delivers fair bandwidth distribution between different traffic classes.
  • We can execute WFQ in NS2 by setting up the diverse queues for each traffic type.

Example:

$ns queue-limit $n1 $n2 10 ;# WFQ configuration here

4.2 Priority Scheduling

  • We can allocate diverse priority levels to different traffic types. This is usually completed via class-based queuing, in which high-priority traffic is processed first.

Example:

$ns queue-priority $n1 $n2 1  ;# Higher priority for node n1->n2 link

$ns queue-priority $n2 $n3 2  ;# Lower priority for node n2->n3 link

4.3 Traffic Policing and Shaping

  • Traffic policing bounds the rate of traffic flows, make certain they don’t exceed a certain threshold.
  • Traffic shaping latency excess packets to rheostat the traffic rate and make sure smoother traffic flow.

4.4 Service Differentiation

  • We need to allocate diverse classes of service to different traffic types using DiffServ (Differentiated Services) in NS2. This enable for granular control over how each flow is managed in terms of latency, packet loss, and bandwidth.
  1. Run the Simulation
  • Save the script as qos_topology.tcl and executed it using the following command:

ns qos_topology.tcl

  1. Analyse QoS Results
  • After running the simulation, we will acquire trace files (out.tr) and NAM files (out.nam).
  • We can use tools such as AWK or Perl to process the trace file and evaluate QoS parameters such as:
    • Throughput
    • End-to-end delay
    • Packet loss rate
    • Jitter

For instance, to estimate throughput from the trace file, we can extract related information using an AWK script that processes TCP/CBR packets received.

  1. Visualize the Network

To envision the network topology and traffic flow, we can open the NAM animation file:

nam out.nam

  1. Extend the QoS Configuration

We can expand this QoS implementation by:

  • Adding more traffic sources (video, voice).
  • Executing real-time protocols (RTP) and validating the QoS guarantees for latency-sensitive traffic.
  • Setup DiffServ or IntServ (Integrated Services) to guarantee diverse service levels for several flows.

In the conclusion, we entirely learn and understood about how the Network Quality of Service (QoS) attainment will analyse the results in the network simulation using ns2 tool. More information regarding the Network Quality of Service (QoS) attainment will also be provided.