How to Implement Network Autonomous in NS2

To implement the Network Autonomy using NS2 that refers to creating a network, which can self-manage, create decisions autonomously, and enhance the performance without human intervention. Such networks can be adjusted to react to failures, enhance the routing, altering conditions and balance traffic actively.

In the simulation platform NS2, we can replicate the network autonomous performances by integrating the below concepts:

  1. Dynamic Routing Protocols: Permit the network autonomously then select the finest for data transmission.
  2. Self-Organizing Networks: These nodes, which autonomously handle its links and routes rely on the network conditions.
  3. Adaptive Traffic Management: Execute the traffic shaping, load balancing, or congestion control, which responds to altering traffic patterns.
  4. Failure Recovery: Allow the network to reroute traffic automatically in case of the link or node failures.

Example: Autonomous Routing in NS2 Using Dynamic Routing Protocols

A significant characteristics of this networks is the capability to actively adjust routing of traffic in react to network conditions. In the simulation network NS2, it can replicate by using dynamic routing protocols like Ad-hoc On-Demand Distance Vector (AODV), Dynamic Source Routing (DSR), or Link State Routing protocols.

The following is an instance on how to replicate this network, which can be rerouted the traffic according to the dynamic conditions using the AODV routing protocol.

Steps for Implementing Autonomous Network in NS2:

  1. Set up the Network Topology: Describe the nodes, links, and dynamic routing protocols.
  2. Enable Dynamic Routing: It use a protocol such as AODV to permit the network to adapt routing paths.
  3. Simulate Traffic: Make a traffic among the nodes and we monitor how the network autonomously handles routing.
  4. Simulate Failures or Network Changes: Examine the autonomy by mimicking failures and also monitoring the rerouting process.

Example TCL Script for Autonomous Network with AODV Routing:

# Create a new simulator instance

set ns [new Simulator]

# Define output trace file for logging events

set tracefile [open autonomous_network.tr w]

$ns trace-all $tracefile

# Define the animation file for NAM (optional)

set namfile [open autonomous_network.nam w]

$ns namtrace-all $namfile

# Create network nodes (5 autonomous nodes)

set n0 [$ns node]

set n1 [$ns node]

set n2 [$ns node]

set n3 [$ns node]

set n4 [$ns node]

# Enable AODV (Ad-hoc On-Demand Distance Vector) routing protocol

$ns rtproto DV  # DV refers to Distance Vector protocols like AODV

# Create links between the nodes with varying bandwidths and delays

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

$ns duplex-link $n1 $n2 5Mb 20ms DropTail

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

$ns duplex-link $n3 $n4 1Mb 30ms DropTail

$ns duplex-link $n0 $n4 5Mb 40ms DropTail  # Direct link from n0 to n4 (higher delay)

# Define a TCP agent for node n0 (sender)

set tcp0 [new Agent/TCP]

$ns attach-agent $n0 $tcp0

# Define a TCP Sink agent for node n4 (receiver)

set sink [new Agent/TCPSink]

$ns attach-agent $n4 $sink

# Connect the TCP agent (n0) to the TCP Sink (n4)

$ns connect $tcp0 $sink

# Define an FTP application to generate traffic over the TCP connection

set ftp [new Application/FTP]

$ftp attach-agent $tcp0

# Schedule the FTP traffic to start and stop

$ns at 0.5 “$ftp start”

$ns at 4.0 “$ftp stop”

# Schedule the failure of the direct link between n0 and n4 at 2.5 seconds

$ns at 2.5 “$ns rtmodel-at 2.5 down $n0 $n4”

# Allow the AODV protocol to autonomously reroute traffic through other nodes

# without any manual intervention

# Set simulation end time at 5.0 seconds

$ns at 5.0 “finish”

# Define the finish procedure to close files and run NAM

proc finish {} {

global ns tracefile namfile

$ns flush-trace

close $tracefile

close $namfile

exec nam autonomous_network.nam &

exit 0

}

# Run the simulation

$ns run

Explanation of the Script:

  1. Network Topology Setup:
    • The script configures five nodes (n0 to n4) with various links among them. The links have changing the bandwidths (1Mb, 5Mb, etc.) and delays (10ms, 30ms, etc.).
    • A duplex link directly relates the nodes n0 and n4 with higher delay, however it works as a shortcut for traffic among the two nodes.
  2. AODV Dynamic Routing:
    • The AODV protocol (a dynamic distance-vector routing protocol) is permitted using $ns rtproto DV. It permits the nodes to autonomously determine and find the optimal routes depends on the network conditions.
    • While the key route among the nodes n0 and n4 fails (due to the link failure at 2.5 seconds), AODV autonomously reroutes the traffic through the intermediate nodes like n1, n2, and n3.
  3. Traffic Generation:
    • A TCP Sink agent is attached to n4 (the receiver).and a TCP agent is related to n0 (the sender), and An FTP application is used to make a traffic across the TCP connection.
    • The FTP traffic begins at 0.5 seconds and ends at 4.0 seconds.
  4. Simulating Link Failure:
    • The direct link among the nodes n0 and n4 is intentionally failed at 2.5 seconds using $ns rtmodel-at 2.5 down $n0 $n4. It forces the AODV protocol to autonomously discover another path for the traffic.
  5. Network Autonomy:
    • The vital to its replication, after the failure that the autonomy of the routing protocol (AODV) within rerouting traffic. There is no manual intervention needed—AODV automatically finds another path through the various nodes.
  1. Monitoring the Autonomous Behavior

The trace file (autonomous_network.tr) records all the events that containing the packet transmissions, receptions, and routing changes. We can estimate the trace file to monitor how the network autonomously adjusts to changes.

Important Metrics to Monitor:

  • Routing Table Changes: Monitor how the routing table updates actively while the link fails and traffic is rerouted.
  • End-to-End Delay: Calculate the delay before and after the link failure to compute the effect on network performance.
  • Packet Loss: Trace how many packets during the transition period are lost while the link fails and traffic is rerouted.
  • Throughput: Calculate the throughput to observe if the network maintains performance after the failure.
  1. Advanced Autonomous Features in NS2

Beyond simple dynamic routing, we can execute further sophisticated autonomous features in NS2:

  1. Autonomous Load Balancing:
  • We can use the dynamic load balancing methods in which the network autonomously modifies the traffic distribution over various paths depends on the network load.
  1. Self-Healing Networks:
  • Replicate the networks, which automatically reroute or repair themselves after node or link failures by set up alternative routes or paths.
  1. Adaptive Traffic Shaping:
  • Execute an adaptive traffic shaping mechanisms, which modify the traffic rates rely on real-time network conditions (e.g., congestion, bandwidth availability).

Example: Load Balancing with Multiple Links

We can describe several links among the nodes and replicate the autonomous load balancing by actively modifying the traffic flow.

# Additional link between n0 and n2 for load balancing

$ns duplex-link $n0 $n2 5Mb 30ms DropTail

# Load balancing can be achieved by the routing protocol (AODV) or using custom scripts

  1. Simulating Autonomous Failure Recovery

This autonomous failure recovery within NS2 can be mimicked by purposely causing the failures (e.g., disabling links or nodes) as well as monitoring how the network adjusts without human intervention. Also we can be used the self-organizing protocols such as OLSR (Optimized Link State Routing) to actively repair routes.

Example: Node Failure

We can replicate the failure of an entire node (n2) and observe the network reroute traffic through other paths.

# Simulate node failure by disabling all links from node n2 at 2.5 seconds

$ns at 2.5 “$ns rtmodel-at 2.5 down $n2”

To finish, we clarified the steps and provided some instances of performing and evaluating the Network Autonomous in NS2, following the above outlined process. More informations will be shared if necessary.

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