How to Implement Network Message Dissemination in NS2

To implement the Network Message Dissemination in NS2, we have to simulate the process of broadcasting or multicasting messages through a network, making certain dispersion of messages from one or several sources to a pair of destination nodes. It is often used in an environment like sensor networks, vehicular networks or emergency broadcast systems. For implementing network message dissemination in the NS2 tool, contact us for the best guidance. Our team has all the necessary resources to provide you with timely support.

Here is the complete guide to implementing Network Message Dissemination in NS2:

Step-by-Step Process for Network Message Dissemination in NS2

  1. Understand Message Dissemination Requirements:
  • Message Dissemination: This is the process of allocating messages from one or several nodes to a group of other nodes in the network.
  • Usual dissemination methods include broadcasting, multicasting, or gossiping:
    • Broadcasting: The message is delivered to all nodes in the network.
    • Multicasting: The message is sent to a particular group of nodes.
    • Flooding: The message is sent to all neighboring nodes, which propagate it further.
  1. Set Up the Network Topology:
  • Configure the nodes in your network and the links amongst them. In this setup, you will simulate a network where one or more nodes disseminate messages to other nodes.
  • You can generate a broadcast network where a node sends messages to all other nodes.

Example OTcl script for a basic network topology:

set ns [new Simulator]

set nf [open out.tr w]

$ns trace-all $nf

set namfile [open out.nam w]

$ns namtrace-all $namfile

# Create network nodes

set node0 [$ns node]  ;# Source node (disseminates messages)

set node1 [$ns node]

set node2 [$ns node]

set node3 [$ns node]

set node4 [$ns node]

# Create duplex links between nodes

$ns duplex-link $node0 $node1 1Mb 10ms DropTail

$ns duplex-link $node0 $node2 1Mb 10ms DropTail

$ns duplex-link $node1 $node3 1Mb 10ms DropTail

$ns duplex-link $node2 $node4 1Mb 10ms DropTail

# Define dissemination process at specific times

$ns at 1.0 “start_dissemination $node0”

$ns at 6.0 “finish”

proc finish {} {

global ns nf namfile

$ns flush-trace

close $nf

close $namfile

exec nam out.nam &

exit 0

}

$ns run

  1. Define the Dissemination Protocol Logic:
  • You can pick to use an available protocol like AODV or DSDV for message dissemination, or you can build your own custom dissemination protocol.
  • Accomplish custom dissemination logic by altering the packet sending and packet receiving logic to assist broadcasting or multicasting.

Example: Simple Broadcast Dissemination:

  • Execute a function that permits a node to send a message to all its neighbors (broadcast).

In node.cc, add a message dissemination function:

void Node::broadcastMessage(Packet* p) {

for (int i = 0; i < num_neighbors_; i++) {

sendPacketToNeighbor(p, neighbors_[i]);

}

}

void Node::sendPacketToNeighbor(Packet* p, Node* neighbor) {

Packet* new_p = p->copy();  // Create a copy of the packet for each neighbor

send(new_p, neighbor->getID());

}

  • The broadcastMessage function delivers the same message to all neighboring nodes, while sendPacketToNeighbor takes care of dispatching the packet to each neighbor.
  1. Implement Flooding or Multicast Mechanism (Optional):
  • For flooding: All nodes that obtain the message dispatches it to all its neighbors, making sure the message reaches every node in the network.
  • To prevent infinite loops (in flooding), use features such as:
    • Hop count: Set a limit on how far the message can propagate.
    • Duplicate message suppression: Each node keeps track of previously obtained messages and doesn’t forward replicas.

Example of flooding with hop count:

void Node::receiveMessage(Packet* p) {

hdr_dissemination* hdr = hdr_dissemination::access(p);

if (hdr->hop_count > 0) {

broadcastMessage(p);

hdr->hop_count–;

}

}

  • In this instance, the message is progressed to neighbors until the hop count reaches zero.
  1. Handle Message Dissemination at Each Node:
  • Establish a receive function at every node that processes the incoming message, assess its authenticity (e.g., not a duplicate), and decides whether to forward it.

Example code in node.cc:

void Node::receive(Packet* p) {

hdr_dissemination* hdr = hdr_dissemination::access(p);

// Check if the message is a duplicate

if (receivedMessages.find(hdr->msg_id) == receivedMessages.end()) {

// Process the message

receivedMessages.insert(hdr->msg_id);  // Mark message as received

// Disseminate the message further (broadcast or multicast)

if (hdr->type == BROADCAST) {

broadcastMessage(p);  // Broadcast to neighbors

} else if (hdr->type == MULTICAST) {

multicastMessage(p);  // Multicast to a specific group

}

}

}

  • Here, the receive function validates if the message has already been obtained (to ignore duplicates), processes the message, and dispatches it to neighbors in terms of its type (broadcast or multicast).
  1. Modify OTcl Script to Trigger Dissemination:
  • Imitate the message dissemination process by using OTcl script. This encompasses generating a message at the source node and activating the dissemination logic.

Example OTcl command to start message dissemination:

proc start_dissemination {src_node} {

global ns

# Create a packet to disseminate

set p [new Packet]

set hdr [hdr_dissemination::access $p]

hdr set_msg_id 1  ;# Unique message ID

hdr set_hop_count 5  ;# Hop limit

hdr set_type BROADCAST  ;# Set type to broadcast

 

# Broadcast message from source node

$src_node broadcastMessage $p

}

  • This script produces a message and broadcasts it from the source node to all neighbors, starting the dissemination process.
  1. Compile and Run the Simulation:
  • After execution the dissemination logic in the C++ files (e.g., node.cc), recompile NS2:

make clean

make

  • Execute your OTcl script to replicate message dissemination:

ns your_script.tcl

  1. Analyze the Results:
  • Assess the dissemination process by testing if the message reaches all nodes or a particular set of nodes.
  • Trace files or NAM (Network Animator) is used to visualize the dissemination of messages across the network.

Example of using an AWK script to asses message dissemination:

awk ‘{if ($1 == “r” && $4 == “dissemination”) print “Message received at”, $3}’ out.tr

  • This script extracts events where nodes receive dissemination messages, permitting you to validate that the message reached all intended nodes.

Key Concepts for Network Message Dissemination:

  1. Dissemination Techniques: Pick amongst broadcast, multicast, or flooding for message dissemination.
  2. Dissemination Protocol: Execute or alter a protocol to manage message dissemination. Make sure it manages duplicate messages and prevents infinite loops.
  3. Message Suppression and Hop Limit: Use mechanisms like hop count and duplicate suppression to control the dissemination.
  4. Trace Analysis: Evaluate the dissemination process and validate its effectiveness by using trace files or visual tools like NAM.

Follow the detailed guide that were presented in this manual regarding the implementation of Message Dissemination into the network using ns2 by defining the network topology and executing Flooding or Multicast Mechanism to achieve it.