How to Implement Network Policy Management in NS2

To implement the Network Policy Management in NS2, we need to set up, enable and observe the policies which controls the network activities, traffic flow and access control. It contains rules based on the bandwidth allocation, traffic preference, security, Quality of Service (QoS) and routing decisions. Since NS2 lacks the in-built mechanisms for advanced policy frameworks like those in SDN (Software-Defined Networking). So, we have to execute it by stating rules in the simulation script that governs how traffic is routed, favoured and handled in terms of specified conditions. Here in the following below, you can see the detailed process to execute it in ns2:

Steps to Implement Network Policy Management in NS2:

  1. Define Network Topology: Configure the nodes and links indicating the network.
  2. Establish Policies: Execute rules or policies for routing, traffic prioritization, bandwidth allocation, or security.
  3. Simulate Traffic: Produce traffic patterns that require policy enforcement (such as various preferences for different traffic types).
  4. Enforce Policies Dynamically: Use scripts to dynamically apply or alter policies during the simulation depend on traffic or network conditions.
  5. Monitor and Analyze Performance: Use trace files to track how policies impact network performance includes throughput, delay, packet loss, and traffic management.

Example: Implementing Network Policy Management in NS2

In this simulation, we will simulate an environment where:

  • Traffic prioritization is established to various types of traffic (like video streaming and file transfers).
  • Bandwidth allocation policies are enforced according to its traffic load.
  • Routing decisions are made dynamically based on network conditions.

Example TCL Script for Network Policy Management:

# Create a new NS2 simulator instance

set ns [new Simulator]

# Define output trace file for logging events

set tracefile [open network_policy_management.tr w]

$ns trace-all $tracefile

# Define animation file for NAM (optional)

set namfile [open network_policy_management.nam w]

$ns namtrace-all $namfile

# Create network nodes: Clients, a router, and a server

set client1 [$ns node]   # Client 1

set client2 [$ns node]   # Client 2

set router [$ns node]    # Router

set server [$ns node]    # Server

# Create links between the nodes (representing network connections)

$ns duplex-link $client1 $router 10Mb 10ms DropTail

$ns duplex-link $client2 $router 10Mb 10ms DropTail

$ns duplex-link $router $server 50Mb 10ms DropTail

# Example 1: Bandwidth Allocation Policy

# Dynamically allocate bandwidth to prioritize video streaming (Client 2) over file transfers (Client 1)

proc apply_bandwidth_policy {} {

global ns client1 client2 router

puts “Applying bandwidth allocation policy…”

# Check some condition (e.g., traffic load) and apply policies accordingly

if {[rand] < 0.5} {

puts “Prioritizing Client 2 (video streaming)”

$ns queue-limit $client1 $router 50

$ns queue-limit $client2 $router 100

} else {

puts “Equally balancing bandwidth between clients”

$ns queue-limit $client1 $router 75

$ns queue-limit $client2 $router 75

}

}

# Example 2: Traffic Prioritization Policy

# Prioritize traffic from Client 1 (e.g., file transfers) based on specific conditions

proc apply_traffic_prioritization_policy {} {

global ns client1 client2 router

puts “Applying traffic prioritization policy…”

# Set different priorities for different traffic types

$ns at 2.0 “$ns link $client1 $router queue-limit 100”

$ns at 2.0 “$ns link $client2 $router queue-limit 50”

}

# Example 3: Dynamic Routing Policy

# Dynamically change routing decisions based on traffic or network conditions

proc apply_routing_policy {} {

global ns router server client1 client2

puts “Applying dynamic routing policy…”

# Simulate rerouting traffic from Client 2 to the server based on traffic load

if {[rand] < 0.5} {

puts “Rerouting traffic from Client 2 through Router”

$ns at 3.0 “$ns rtmodel-at 3.0 down $client2 $router”

$ns at 4.0 “$ns rtmodel-at 4.0 up $client2 $router”

}

}

# Define traffic for Client 1 (TCP – File Transfer)

set tcp_client1 [new Agent/TCP]

$ns attach-agent $client1 $tcp_client1

set tcp_sink [new Agent/TCPSink]

$ns attach-agent $server $tcp_sink

$ns connect $tcp_client1 $tcp_sink

set ftp_client1 [new Application/FTP]

$ftp_client1 attach-agent $tcp_client1

# Define traffic for Client 2 (UDP – Video Streaming)

set udp_client2 [new Agent/UDP]

$ns attach-agent $client2 $udp_client2

set udp_sink [new Agent/Null]

$ns attach-agent $server $udp_sink

$ns connect $udp_client2 $udp_sink

set cbr_client2 [new Application/Traffic/CBR]

$cbr_client2 attach-agent $udp_client2

$cbr_client2 set packetSize_ 1000

$cbr_client2 set rate_ 2Mb

$cbr_client2 set interval_ 0.01

# Schedule the start of traffic

$ns at 0.5 “$ftp_client1 start”

$ns at 0.5 “$cbr_client2 start”

# Apply network policies dynamically during the simulation

$ns at 1.0 “apply_bandwidth_policy”

$ns at 2.0 “apply_traffic_prioritization_policy”

$ns at 3.0 “apply_routing_policy”

# Schedule the stop time for traffic

$ns at 4.0 “$ftp_client1 stop”

$ns at 4.0 “$cbr_client2 stop”

# End the simulation at 5.0 seconds

$ns at 5.0 “finish”

# Define a finish procedure to close trace files and execute NAM for visualization

proc finish {} {

global ns tracefile namfile

$ns flush-trace

close $tracefile

close $namfile

exec nam network_policy_management.nam &

exit 0

}

# Run the simulation

$ns run

Explanation of the Script:

  1. Network Topology:
    • We set up a simplified topology with two clients, a router, and a server. Each client has a link to the router, and the router is linked to the server.
  2. Policy Management Logic:
    • Bandwidth Allocation Policy: Dynamically allot bandwidth amongst Client 1 (file transfer) and Client 2 (video streaming) depends on current traffic conditions. The policy can favour one client’s traffic by maximizing its queue limit.
    • Traffic Prioritization Policy: Prefer particular variant of traffic like file transfers, over others. This is accomplished by modifying the queue limits at the router for each client.
    • Dynamic Routing Policy: Replicate a scenario where traffic from Client 2 is rerouted because of varying network conditions like traffic congestion.
  3. Traffic Simulation:
    • Client 1 delivers TCP traffic (file transfers via FTP) to the server.
    • Client 2 delivers UDP traffic (video streaming via CBR) to the server.
  4. Policy Application:
    • The policies are applied dynamically at various times during the simulation:
      • Bandwidth Allocation Policy is applied at 1.0 seconds to prefer bandwidth amongst clients.
      • Traffic Prioritization Policy is applied at 2.0 seconds to prioritize file transmits over video streaming.
      • Dynamic Routing Policy is applied at 3.0 seconds, simulating traffic redirecting from Client 2.
  5. Simulation Control:
    • The traffic begins at 0.5 seconds and ends at 4.0 seconds. The simulation executes for 5.0 seconds in total, during which the network policies are applied dynamically.
  1. Analyzing the Impact of Policies

After the simulation, you can evaluate the trace file (network_policy_management.tr) to understand how the policies impacts network performance.

  1. a) Throughput:

Compute throughput for TCP traffic (file transfers) by using the below command:

awk ‘$1 == “r” && $4 == “tcp” { total_bytes += $5 } END { print “Throughput: “, total_bytes/5, “bytes/sec” }’ network_policy_management.tr

This command estimates the total bytes obtained over the simulation and gives the average throughput.

  1. b) Packet Loss:

To calculates the number of dropped packets, use:

awk ‘$1 == “d” { total_dropped++ } END { print “Packet Loss: “, total_dropped }’ network_policy_management.tr

This will sum up the count of packets dropped during the simulation, which may result from congestion or rerouting.

  1. c) Latency:

To measure the average latency for TCP traffic:

awk ‘

/^s/ && $4 == “tcp” { sent[$6] = $2 }

/^r/ && $4 == “tcp” { if ($6 in sent) { total_delay += ($2 – sent[$6]); total_packets++ } }

END { print “Average Latency: “, total_delay/total_packets, “seconds” }’ network_policy_management.tr

This script computes the average delay experienced by packets amongst delivering and obtaining.

  1. Advanced Policy Management Features

To optimize the policy management simulation, you can:

  • QoS-Based Policy Management: Execute more granular Quality of Service (QoS) rules in terms of packet types, application types, or user profiles.
  • Security Policies: Simulate access control or firewall rules to block specific kinds of traffic or apply security policies according to the traffic source or destination.
  • Real-Time Feedback: Dynamically alter the policies during the simulation by using realistic metrics (includes network load, delay, packet loss).

The above structured manual has the essential information regarding the Policy management and how to implement it into the network by defining the network topology and establishing some rules and assessing the outcomes of the simulation. You can also include some latest functionality into it as per your requirements. Let us know what you need, and we’ll help you out with more info. If you’re looking for extra help with Network Policy Management in the NS2 tool, check out ns2project.com for more tips on your setup. Our team focuses on how traffic is managed, prioritized, and processed based on specific conditions, plus we can suggest some great project topics. We’re here to provide top-notch network analysis for your project.