How to Start Voice over IP Projects Using NS2

To start a Voice over IP (VoIP) project using NS2 that has encompasses to replicate the real-time voice interaction through an IP-based network. VoIP projects contain the voice traffic’s simulation to leverage RTP (Real-Time Protocol) over UDP, together with SIP or H.323 for Signaling. NS2 environment can be replicated the VoIP by way of simulating their traffic and examining the performance of network in diverse scenarios.

Following is a common procedure to get started:

Steps to Start VoIP Projects in NS2

  1. Understand VoIP
  • VoIP Basics:
    • It sends voice packets through IP networks to utilize the RTP/UDP.
    • Exhausts SIP, H.323, or same protocols for session initiation and management.
    • Crucial performance parameters like latency, jitter, packet loss, and Mean Opinion Score (MOS).
  • Project Goals:
    • Replicate the VoIP traffic.
    • Examine QoS indicators such as latency, jitter, and throughput.
    • Experiment the performance in diverse network conditions such as congestion, delays.
  1. Install and Set Up NS2
  1. Install NS2:

sudo apt-get install ns2

  1. Verify Installation: Run:

ns

If start the NS2 terminal then it effectively installed.

  1. VoIP in NS2: While NS2 doesn’t directly have support for VoIP, we will need to replicate it for voice traffic to utilize RTP over UDP and SIP-like signaling with TCP.
  1. Define the Project Scope

Focus on the project objective like:

  • Replicate the end-to-end VoIP interaction.
  • Examine network performance on metrics like jitter, packet loss.
  • Equate the QoS with and without congestion.
  1. Create the Network Topology

Make a network topology including:

  • VoIP Source (Caller): Replicates the voice sender.
  • VoIP Destination (Receiver): It mimics voice receiver.
  • Intermediate Nodes: It has routers or switches within the network.
  1. Write a TCL Script

Below is an instance of TCL script for replicating a basic VoIP session:

Example TCL Script:

# Create a new simulator instance

set ns [new Simulator]

# Open trace and NAM files

set tracefile [open voip_simulation.tr w]

$ns trace-all $tracefile

set namfile [open voip_simulation.nam w]

$ns namtrace-all $namfile

# Create nodes for VoIP Source, Intermediate Router, and Destination

set src [$ns node]

set router [$ns node]

set dest [$ns node]

# Define links with bandwidth and delay

$ns duplex-link $src $router 1Mb 10ms DropTail

$ns duplex-link $router $dest 1Mb 10ms DropTail

# Attach UDP agents to simulate RTP traffic

set udp_src [new Agent/UDP]

$ns attach-agent $src $udp_src

set udp_sink [new Agent/Null]

$ns attach-agent $dest $udp_sink

$ns connect $udp_src $udp_sink

# Simulate RTP traffic using a CBR application

set rtp [new Application/Traffic/CBR]

$rtp attach-agent $udp_src

$rtp set packetSize_ 160  ; # Typical VoIP packet size (20ms audio at 64kbps)

$rtp set interval_ 0.02   ; # Interval of 20ms

# Start and stop VoIP traffic

$ns at 0.5 “$rtp start”

$ns at 5.0 “$rtp stop”

# End simulation

$ns at 6.0 “finish”

proc finish {} {

global ns tracefile namfile

$ns flush-trace

close $tracefile

close $namfile

exec nam voip_simulation.nam &

exit 0

}

$ns run

  1. Run the Simulation
  1. We can store the simulation tcl script like voip_simulation.tcl.
  2. Execute the simulation:

ns voip_simulation.tcl

  1. We need to envision the network with NAM:

nam voip_simulation.nam

  1. Analyze VoIP Performance

Examine the .tr trace file for:

  • Latency: Estimate the endwise delay for packets.
  • Jitter: Compute the difference in packet delay.
  • Packet Loss: Measure the rate of packets that are effectively dropped.
  • Throughput: Determine the percentage of data transmission.

Example AWK Script for Latency:

BEGIN { count=0; total_delay=0; }

$1 == “r” && $4 == “dest” {

delay = $2 – $8;

total_delay += delay;

count++;

}

END {

print “Average Latency: ” total_delay/count ” ms”;

}

  1. Experiment with Advanced Scenarios
  1. Network Congestion: Integrate the background traffic for replicating network congestion:

set tcp_bg [new Agent/TCP]

$ns attach-agent $router $tcp_bg

set null_bg [new Agent/Null]

$ns attach-agent $dest $null_bg

$ns connect $tcp_bg $null_bg

  1. Dynamic Topology: Mimic node or link failures in dynamic topology:

$ns at 3.0 “$ns link-down $router $dest”

  1. QoS Mechanisms: Execute the Differentiated Services (DiffServ) or priority queues for VoIP traffic utilising QoS approaches.
  1. Enhance the Project
  1. SIP Signaling: We can replicate the SIP-like behavior for session initiation to leverage TCP agents.
  2. Codecs: Adapt VoIP traffic metrics for simulating diverse codecs like G.711, G.729.
  3. Wireless Networks: We need to prolong the simulation to wireless VoIP through Wi-Fi or LTE.
  1. Document Your Findings

The project should contain following aspects:

  • Project’s objectives and mechanisms.
  • Network configuration for topology and metrics.
  • Results: Latency, jitter, packet loss, and throughput.
  • Finally, it provides insights and conclusions.
  1. Tools for Advanced Analysis
  • MATLAB/Python: For in-depth analysis and visualization of QoS parameters to utilize these tools.
  • Third-Party Tools: Add NS2 including third-party tools such as Wireshark for packet-level analysis.

At the end of these simulations, we comprehended the entire simulation process with sample snippets on how to start and analyze the Voice over IP Projects in NS2 tool. For further use, you can be able to get information about this topic from us.