How to Implement Network Coding in NS2

To implement the network coding is a method, used in network communication to maximise throughput and robustness by permitting the intermediate nodes, before sending them that to aggregate the packets. In traditional routing, these nodes are just forward packets without modifying them, however with nodes mix (or code) data packets together, network coding,  permitting more effective use of the network capacity as well as enhancing the performance.

In NS2, it can execute by changing how packets are processed at intermediate nodes before forwarding them that can aggregate the incoming packets. The execution of network coding within NS2 needs some changes to the way packets are received, processed, and transmitted. Below is a basic techniques for execute the Network coding in NS2:

Steps to Implement Network Coding in NS2:

  1. Create Network Topology: Configure the nodes are signifying sources, intermediate nodes (where coding happens), and ends.
  2. Simulate Packet Mixing (Coding): Change the performance of the intermediate nodes to combine the packets before forwarding them.
  3. Simulate Decoding at Destination: The end nodes are require to able to decrypt the combined packets to recover the original data.
  4. Monitor Performance: It use the trace files to examine the performance improvements (throughput, packet loss, etc.) while using network coding.

Key Concepts in Network Coding:

  • Linear Network Coding: A basic and generally used form of the network coding in which packets are combined using linear operations (e.g., XOR or addition of packet contents).
  • Intermediate Nodes (Coding Nodes): This nodes are aggregate several incoming packets and transfer the coded packet to the next node or end.
  • Decoding: At the destination, the combined packets are decrypted to recover the original packets.

Example Scenario: Network Coding in NS2

Consider, replicate a simple butterfly network, a well-known topology for representing the network coding. This network will have:

  • Two sources are transmitting various packets.
  • An intermediate node, which combines (codes) the packets.
  • Two ends that decode the received packets.

Example TCL Script for Network Coding in NS2:

# Create a new simulator instance

set ns [new Simulator]

# Define output trace file

set tracefile [open network_coding.tr w]

$ns trace-all $tracefile

# Define animation file for NAM (optional)

set namfile [open network_coding.nam w]

$ns namtrace-all $namfile

# Create nodes for the butterfly network

set source1 [$ns node]   # Source 1

set source2 [$ns node]   # Source 2

set relay1 [$ns node]    # Relay 1 (Intermediate node)

set relay2 [$ns node]    # Relay 2 (Coding node)

set destination1 [$ns node] # Destination 1

set destination2 [$ns node] # Destination 2

# Create links between the nodes to form a butterfly network

$ns duplex-link $source1 $relay1 10Mb 10ms DropTail

$ns duplex-link $source2 $relay1 10Mb 10ms DropTail

$ns duplex-link $relay1 $relay2 10Mb 10ms DropTail

$ns duplex-link $relay2 $destination1 10Mb 10ms DropTail

$ns duplex-link $relay2 $destination2 10Mb 10ms DropTail

# —————- Network Coding Functionality —————-

# Define UDP agents for Source 1 and Source 2 to send packets

set udp_source1 [new Agent/UDP]

$ns attach-agent $source1 $udp_source1

set udp_source2 [new Agent/UDP]

$ns attach-agent $source2 $udp_source2

# Define Null agents for Destination 1 and Destination 2 (receive coded packets)

set sink_dest1 [new Agent/Null]

$ns attach-agent $destination1 $sink_dest1

set sink_dest2 [new Agent/Null]

$ns attach-agent $destination2 $sink_dest2

# Connect Source 1 and Source 2 to the relay node (Relay 1)

$ns connect $udp_source1 $sink_dest1

$ns connect $udp_source2 $sink_dest2

# Network Coding at Relay2: Combine the two incoming packets

# Simulate network coding by mixing packets from relay1 at relay2 (e.g., using XOR)

proc network_coding {} {

global udp_source1 udp_source2 relay2 destination1 destination2

# Get packet from source1 and source2

# Perform XOR operation or linear combination of the packets

# Forward the mixed packet to destination1 and destination2

puts “Performing network coding at relay node…”

}

# Define traffic generators to simulate traffic from Source 1 and Source 2

set cbr_source1 [new Application/Traffic/CBR]

$cbr_source1 attach-agent $udp_source1

$cbr_source1 set packetSize_ 512

$cbr_source1 set rate_ 1Mb

$cbr_source1 set interval_ 0.1

$ns at 0.5 “$cbr_source1 start”

set cbr_source2 [new Application/Traffic/CBR]

$cbr_source2 attach-agent $udp_source2

$cbr_source2 set packetSize_ 512

$cbr_source2 set rate_ 1Mb

$cbr_source2 set interval_ 0.1

$ns at 0.5 “$cbr_source2 start”

# Schedule the network coding function

$ns at 1.0 “network_coding”

# Schedule the end of the simulation

$ns at 5.0 “finish”

# Define finish procedure

proc finish {} {

global ns tracefile namfile

$ns flush-trace

close $tracefile

close $namfile

exec nam network_coding.nam &

exit 0

}

# Run the simulation

$ns run

Explanation of the Script:

  1. Node Setup:
    • We make a nodes for Source 1, Source 2, Relay 1, Relay 2, Destination 1, as well as Destination 2 to form the butterfly network.
    • Relay nodes are replicate the intermediate nodes in which the network coding happens.
  2. Link Setup:
    • Duplex links are made among the nodes with bandwidth (10Mb) and delay (10ms) to replicate the communication channels within the network.
  3. Traffic Generation:
    • UDP agents are connected to Source 1 and Source 2 to replicate the packet transmission.
    • Null agents are attached to the end to receive packets.
    • CBR (Constant Bit Rate) traffic generators mimic regular packet flows from Source 1 and Source 2 to their corresponding ends.
  4. Network Coding:
    • The function network_coding is a placeholder, which could execute the coding logic at Relay 2. In this instance, we can deliberate of the coding process as combining packets from the Source 1 and Source 2 using an operation such as XOR.
    • They are sent to both Destination 1 and Destination 2, after coding the packets.
  5. Traffic Scheduling:
    • The traffic begins at 0.5 seconds, and network coding is begins at 1.0 second.
    • The simulation runs for 5.0 seconds, after that the trace and NAM files are processed.
  1. Advanced Features in Network Coding

We can expand this simple instance by:

  • Adding Real Network Coding Operations: Rather than the basic placeholder, execute the real coding techniques (e.g., XOR or linear combinations of packets).
  • Simulating Decoding: At the end nodes, execute a mechanism to decode the combined packets and recover the original data.
  • Packet Loss: Replicate packet loss to monitor how network coding can recover from packet loss situations.
  • Different Topologies: Mimic the network coding in various topologies, like wireless mesh networks that to observe how network coding develops the performance.
  1. Analyzing the Trace File

When the simulation finishes, we can estimate the trace file (network_coding.tr) to:

  • Monitor Packet Flows: Observe how packets are sent and coded at the relay nodes.
  • Measure Throughput: Liken the throughput with and without network coding.
  • Measure Packet Loss: Monitor how network coding are manage the situation in which packets are lost.
  1. Decoding at Destination Nodes

For an entire network coding execution, the end nodes will be required to decode the coded packets. It can complete by receiving the numerous coded packets and execution inverse operations (e.g., solving a system of linear equations if linear network coding is used) to recover the original packets.

Example Decoding Logic:

At Destination 1 and Destination 2, execution the decoding to retrieve the original packets:

proc decode_packets {} {

# Perform decoding to retrieve the original packets

puts “Decoding the received packets at the destination…”

}

In the above procedure demonstrated the comprehensive techniques to execute and enforce the Network Coding in NS2 simulation platform. Further specific details will be provided later in another material.

We’re ready to assist you with quick support to ensure your comparison is done perfectly. For help with implementing Network Coding in NS2, visit ns2project.com for great project ideas that fit your research needs.