How to Implement IPv6 Protocol in NS2

 

To implement the IPv6 in ns2, we have to attach or extend the available IPv4’s potential to manage the IPv6-specific mechanisms like larger address space, various header structures, and unique routing features. Since ns2 lacks the support for IPv6, we have to execute it from the beginning or altering the existing modules to simulate IPv6 behavior. This demonstration has the essential information to accomplish this method in ns2:

Step-by-Step Implementation:

Step 1: Understand IPv6 Protocol Features

IPv6 launches several variations from IPv4, such as:

  • 128-bit Addressing: Larger address space.
  • Simplified Header Structure: smaller amount of fields in the header for more efficient processing.
  • Stateless Address Autoconfiguration (SLAAC): For automatically allocating IP addresses.
  • Extension Headers: Extra optional headers for routing, security and more.

Step 2: Set Up NS2

Make certain NS2 is installed and executing properly on your system. Since NS2 is developed mainly for IPv4, implementing IPv6 will demand generating new classes and potentially altering the existing NS2 source code.

Step 3: Implement IPv6 Protocol Features in C++

  1. Define the IPv6 Header Structure

You need to state the IPv6 header structure that contains the basic fields like version, traffic class, flow label, payload length, next header, hop limit, and the source and destination addresses.

#include <packet.h>

struct hdr_ipv6 {

int version;

int traffic_class;

int flow_label;

int payload_length;

int next_header;

int hop_limit;

uint8_t src_addr[16];  // 128-bit source address

uint8_t dest_addr[16]; // 128-bit destination address

static int offset_;

inline static hdr_ipv6* access(const Packet* p) {

return (hdr_ipv6*) p->access(offset_);

}

};

int hdr_ipv6::offset_;

  1. Implement the IPv6 Agent Class

The IPv6 agent class will handle packet forwarding, address set ups, and other IPv6-related tasks.

#include <agent.h>

#include <packet.h>

#include <trace.h>

#include <address.h>

#include <cstring>

class IPv6Agent : public Agent {

public:

IPv6Agent();

void recv(Packet* p, Handler* h);

void forwardPacket(Packet* p);

void configureAddress(uint8_t addr[16]);

protected:

uint8_t ipv6_address_[16];  // Node’s IPv6 address

std::map<std::string, int> routingTable_; // Destination -> Next Hop

};

// Constructor

IPv6Agent::IPv6Agent() : Agent(PT_UDP) {

// Initialize the node’s IPv6 address to zero

memset(ipv6_address_, 0, sizeof(ipv6_address_));

}

// Configure the node’s IPv6 address

void IPv6Agent::configureAddress(uint8_t addr[16]) {

memcpy(ipv6_address_, addr, sizeof(ipv6_address_));

}

// Packet reception

void IPv6Agent::recv(Packet* p, Handler* h) {

hdr_ipv6* ipv6h = hdr_ipv6::access(p);

// Check if the packet is destined for this node

if (memcmp(ipv6h->dest_addr, ipv6_address_, 16) == 0) {

// Process the packet locally

// (You would typically pass it to a higher layer protocol like TCP/UDP)

} else {

// Forward the packet

forwardPacket(p);

}

}

// Forward the packet based on the destination address

void IPv6Agent::forwardPacket(Packet* p) {

hdr_ipv6* ipv6h = hdr_ipv6::access(p);

char dest_addr_str[40]; // For storing the string representation of the address

// Convert the destination address to a string for routing lookup

snprintf(dest_addr_str, sizeof(dest_addr_str), “%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x”,

ipv6h->dest_addr[0], ipv6h->dest_addr[1], ipv6h->dest_addr[2], ipv6h->dest_addr[3],

ipv6h->dest_addr[4], ipv6h->dest_addr[5], ipv6h->dest_addr[6], ipv6h->dest_addr[7],

ipv6h->dest_addr[8], ipv6h->dest_addr[9], ipv6h->dest_addr[10], ipv6h->dest_addr[11],

ipv6h->dest_addr[12], ipv6h->dest_addr[13], ipv6h->dest_addr[14], ipv6h->dest_addr[15]);

if (routingTable_.find(dest_addr_str) != routingTable_.end()) {

int nextHop = routingTable_[dest_addr_str];

send(p, nextHop);

} else {

// Drop packet if no route is found

drop(p);

}

}

  1. Integrate the IPv6 Protocol into NS2
  1. Modify the Makefile: Attach your new IPv6Agent class to the NS2 Makefile so that it gets compiled with the remains of the simulator.
  2. Recompile NS2:

make clean

make

Step 4: Create a Tcl Script to Simulate IPv6

Use the protocol to configure a Tcl script for the simulation of network, once the IPv6 protocol is executed and compiled.

Example Tcl Script:

# Create a simulator object

set ns [new Simulator]

# Define the topology

set val(chan)   Channel/WiredChannel

set val(ll)     LL

set val(ifq)    Queue/DropTail/PriQueue

set val(ifqlen) 50

set val(stop)   50.0

# Initialize the topology object

set topo [new Topography]

$topo load_flatgrid 500 500

# Create nodes

set node1 [$ns node]

set node2 [$ns node]

set node3 [$ns node]

# Establish links between nodes

$ns duplex-link $node1 $node2 10Mb 10ms DropTail

$ns duplex-link $node2 $node3 10Mb 10ms DropTail

# Attach IPv6 agents to nodes

set ipv6_1 [new Agent/IPv6Agent]

set ipv6_2 [new Agent/IPv6Agent]

set ipv6_3 [new Agent/IPv6Agent]

$ns attach-agent $node1 $ipv6_1

$ns attach-agent $node2 $ipv6_2

$ns attach-agent $node3 $ipv6_3

# Configure IPv6 addresses

$ipv6_1 configureAddress “2001:0db8:85a3::8a2e:0370:7334”

$ipv6_2 configureAddress “2001:0db8:85a3::8a2e:0370:7335”

$ipv6_3 configureAddress “2001:0db8:85a3::8a2e:0370:7336”

# Set up traffic sources and sinks

set udp [new Agent/UDP]

set null [new Agent/Null]

$ns attach-agent $node1 $udp

$ns attach-agent $node3 $null

$ns connect $udp $null

# Start the simulation

$ns at 0.0 “$udp start”

$ns at $val(stop) “stop”

$ns at $val(stop) “exit 0”

proc stop {} {

global ns

$ns flush-trace

exit 0

}

# Run the simulation

$ns run

Step 5: Run the Simulation

  1. Store the Tcl script (ipv6_simulation.tcl).
  2. Open a terminal and forward it to the directory where you logged the Tcl script.
  3. Run the simulation using the given command:

ns ipv6_simulation.tcl

Step 6: Analyze the Results

  • Evaluate the IPv6 protocol’s performance based on metrics like packet delivery ratio, latency, and routing efficiency by using trace files and the network animator (NAM).
  • Analyze how well your protocol manages IPv6-specific functionalities like address configuration, packet forwarding, and route management.

Additional Considerations

  • Advanced Features: Consider including modern IPv6 features like Neighbor Discovery, ICMPv6 for error reporting, and support for IPv6 extension headers.
  • Scalability: Assess the scalability and performance by testing the protocol in larger networks with more nodes.
  • IPv6 Transition Mechanisms: Establish and examine transition mechanisms like tunneling (IPv6 over IPv4) or dual-stack configurations.

In this manual, we have delivered the typical procedure that is vital to know when implementing IPv6-based protocols in ns2 environment. We also provide samples for your references. If needed, we will guide you through another procedure for you. If you’re looking to implement the IPv6 protocol in NS2, check out ns2project.com. We’ve got some great project topics to share! Whether you need help starting from scratch or tweaking existing modules for simulation, just send us your project details, and we’ll provide detailed guidance.