How to Implement Software Defined Wide Network in ns2

To implement a Software-Defined Wide Area Network (SD-WAN) in Network Simulator 2 (NS2) has several steps that has includes to mimic a network in which the control plane is decoupled from the data plane that permits the centralized management of the network and dynamic routing decisions. While the NS2 doesn’t have built-in support for SD-WAN, so we can replicate its characteristics by scripting control plane functions and setup the data plane elements like routers and links that dynamically during the simulation. Check out the manual provided to get your Software Defined Wide Area Network up and running with ns2.

Step-by-Step Implementation:

  1. Set Up the NS2 Environment:
  • Make sure NS2 is installed on the computer.
  • Get to know with writing TCL scripts, as NS2 simulations are controlled through TCL.
  1. Define the Network Topology:
  • Generate a network topology with multiple branch offices, data centers, and central controllers that signifies the SD-WAN setup.

# Define the simulator

set ns [new Simulator]

# Create a trace file for analysis

set tracefile [open out.tr w]

$ns trace-all $tracefile

# Create a NAM file for animation

set namfile [open out.nam w]

$ns namtrace-all $namfile

# Define nodes: Branches, Data Center, and SD-WAN Controller

set branch1 [$ns node]

set branch2 [$ns node]

set branch3 [$ns node]

set data_center [$ns node]

set controller [$ns node]

  1. Set Up Links Between Nodes:
  • Introduce the links among the branches, data center, and the controller and these links denotes the WAN connections.

# Create duplex links between branches and data center

$ns duplex-link $branch1 $data_center 10Mb 20ms DropTail

$ns duplex-link $branch2 $data_center 10Mb 30ms DropTail

$ns duplex-link $branch3 $data_center 10Mb 25ms DropTail

# Create a link between the controller and the data center

$ns duplex-link $controller $data_center 100Mb 10ms DropTail

  1. Simulate SD-WAN Controller Functions:
  • The SD-WAN controller is responsible for handling the network. We can mimic the controller by writing TCL protocols that enthusiastically vary the routing decisions or network configurations according to the traffic conditions or predefined policies.

# Define a procedure to simulate SD-WAN controller decisions

proc sdwan_controller {branch data_center policy} {

global ns

# Example policy: Change link parameters based on traffic

if {$policy == “high_traffic”} {

$ns reset-link $branch $data_center 20Mb 15ms DropTail

puts “SD-WAN Controller: High traffic detected, increasing bandwidth.”

} else {

$ns reset-link $branch $data_center 10Mb 20ms DropTail

puts “SD-WAN Controller: Normal traffic, using default settings.”

}

}

# Simulate the controller monitoring traffic and applying policies

$ns at 1.0 “sdwan_controller $branch1 $data_center normal”

$ns at 2.0 “sdwan_controller $branch1 $data_center high_traffic”

  1. Simulate Traffic and Routing Decisions:
  • Attach TCP or UDP agents to the branches to replicate the traffic. The controller can dynamically adapt the routing or link parameters according to the traffic.

# Branch 1 sends data to the data center

set tcp_branch1 [new Agent/TCP]

$ns attach-agent $branch1 $tcp_branch1

set tcp_dc [new Agent/TCPSink]

$ns attach-agent $data_center $tcp_dc

$ns connect $tcp_branch1 $tcp_dc

# Create FTP application to generate traffic

set ftp1 [new Application/FTP]

$ftp1 attach-agent $tcp_branch1

# Start the FTP traffic at 1.0 seconds

$ns at 1.0 “$ftp1 start”

  1. Monitor and Modify Network Behavior:
  • The SD-WAN controller can observe the network and implement the diverse policies or configurations based on the observed traffic. This dynamic adjustment can be emulated by adjusting the link characteristics, routing tables, or other performance metrics.

# Example of dynamically modifying network behavior

$ns at 3.0 “sdwan_controller $branch2 $data_center high_traffic”

$ns at 4.0 “sdwan_controller $branch3 $data_center normal”

  1. Run the Simulation:
  • Describe as they the simulation should terminate and executed it. The finish procedure will close the trace files and launch NAM for visualization.

# Define the finish procedure

proc finish {} {

global ns tracefile namfile

$ns flush-trace

close $tracefile

close $namfile

exec nam out.nam &

exit 0

}

# Schedule the finish procedure at 5 seconds

$ns at 5.0 “finish”

# Run the simulation

$ns run

  1. Analyze the Results:
  • We need to use the trace file (out.tr) to evaluate the packet delivery, latency, throughput, and other parameters.
  • Open the NAM file (out.nam) to visualize the network operations and traffic flow.
  1. Customize and Extend:
  • We can tailor the simulation by:
    • Executing more sophisticated SD-WAN controller logic that takes into account multiple parameters such as delay, jitter, packet loss, or load balancing through multiple links.
    • To mimic diverse routing protocols or failure recovery mechanisms that is handled by the SD-WAN controller.
    • Attaching more branches and discovering multi-path routing approaches in which the SD-WAN controller dynamically prioritize the best path according to real-time network conditions.

Example Summary:

This sample configures the simple SD-WAN simulation in NS2. The branches are associated to a central data center, and an SD-WAN controller enthusiastically handles the network based on predefined policies or real-time traffic conditions. The simulation uses TCP for reliable data transfer, and traffic is created by using FTP applications.

Advanced Considerations:

  • For more complex SD-WAN setting deliberate the combined machine learning techniques for predictive analytics or applying the software-defined networking (SDN) concepts in which the control plane and data plane are more distinctly isolated.
  • Replicate the network events like link failures or congestion and monitor on how the SD-WAN controller reacts to these events in real time.

Debugging and Optimization:

  • Use the trace-all command to debug the simulation and evaluate the packet flows.
  • Enhance the simulation by modifying the TCP metrics, refining the SD-WAN controller logic, and modifying the network properties.

In the above procedures demonstrated the complete procedures to implement and enforce the Software-Defined Wide Area Network in ns2 simulation tool that is efficiently used to handle the network. Additional specific details regarding the SDWAN will also be provided.

We also handle routers and links tailored to your projects. Hit up ns2project.com for top-notch support and to grab some thesis ideas and topics from us.