How to Implement HWMP Protocol in NS2

 

To implement the Hybrid Wireless Mesh Protocol (HWMP) in ns2, we need to understand the protocol due to it is a segment of IEEE 802.11 standard for wireless mesh networks. It integrates On-demand (reactive) and proactive routing methods to permit efficient routing in mesh networks. Follow the implementation steps to accomplish this protocol in ns2:

Step-by-Step Implementation:

Step 1: Understand HWMP Protocol

HWMP is developed for wireless mesh networks and incorporates components of both on-demand (similar to AODV) and proactive routing protocols. It uses two main functions:

  • Proactive Tree Building: Accomplish a tree-based routing structure from the root node.
  • On-Demand Path Discovery: Similar to AODV, routes are found on demand using RREQ (Route Request) and RREP (Route Reply) messages.

Step 2: Set Up NS2

Make certain that you have installed and configured the ns2 properly by following the installation instructions. If you require mesh network support, you may need to expand NS2 or consider using NS3, which has better support for earlier protocols like HWMP.

Step 3: Implement the HWMP Protocol

  1. Create the HWMP Agent Class (C++)

Execute the HWMP routing logic by generate a new C++ class which should manage the following below:

  • Proactive Path Setup: Accomplish a proactive routing tree from the root node.
  • On-Demand Path Discovery: Executes RREQ and RREP messaging for on-demand routes.
  • Route Maintenance: Manage link failures and updates the routing tables accordingly.

Here’s a basic structure:

#include <agent.h>

#include <packet.h>

#include <trace.h>

#include <address.h>

#include <map>

class HWMPAgent : public Agent {

public:

HWMPAgent();

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

void initiateProactivePath();

void discoverRoute(int dest);

void forwardPacket(Packet* p);

void handleLinkBreak();

protected:

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

int rootNode_; // Identifier of the root node for proactive routing

};

// Constructor

HWMPAgent::HWMPAgent() : Agent(PT_UDP), rootNode_(0) {

// Initialization code here

}

// Packet reception

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

hdr_ip* iph = hdr_ip::access(p);

int dest = iph->dst();

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

forwardPacket(p);

} else {

discoverRoute(dest);

}

}

// Initiate proactive path setup from the root node

void HWMPAgent::initiateProactivePath() {

// Implement proactive tree-building logic

}

// Route discovery in HWMP

void HWMPAgent::discoverRoute(int dest) {

// Implement on-demand route discovery using RREQ and RREP packets

}

// Forward packet to the selected next hop

void HWMPAgent::forwardPacket(Packet* p) {

hdr_ip* iph = hdr_ip::access(p);

int nextHop = routingTable_[iph->dst()];

// Code to forward the packet to the next hop

}

// Handle link breaks and rediscover routes

void HWMPAgent::handleLinkBreak() {

// Implement logic for handling link breaks and sending RERR packets

}

  1. Integrate the HWMP Agent into NS2
  1. Modify the Makefile: Include your new HWMPAgent class to the NS2 Makefile so that it gets compiled with the remaining of the simulator.
  2. Recompile NS2:

make clean

make

Step 4: Create a Tcl Script to Simulate HWMP

After the HWMP protocol is executed and compiled, generate a Tcl script to replicate a network using HWMP.

Example Tcl Script:

# Create a simulator object

set ns [new Simulator]

# Define the topology

set val(chan)   Channel/WirelessChannel

set val(prop)   Propagation/TwoRayGround

set val(netif)  Phy/WirelessPhy

set val(mac)    Mac/802_11

set val(ifq)    Queue/DropTail/PriQueue

set val(ll)     LL

set val(ant)    Antenna/OmniAntenna

set val(ifqlen) 50

set val(nn)     10

set val(x)      1000

set val(y)      1000

set val(stop)   100.0

set val(rp)     HWMP   ;# Hybrid Wireless Mesh Protocol

# Initialize the topology object

set topo [new Topography]

$topo load_flatgrid $val(x) $val(y)

# Create the God object

create-god $val(nn)

# Configure the nodes

$ns node-config -adhocRouting $val(rp) \

-llType $val(ll) \

-macType $val(mac) \

-ifqType $val(ifq) \

-ifqLen $val(ifqlen) \

-antType $val(ant) \

-propType $val(prop) \

-phyType $val(netif) \

-channelType $val(chan) \

-topoInstance $topo \

-agentTrace ON \

-routerTrace ON \

-macTrace ON \

-movementTrace ON

# Create nodes

for {set i 0} {$i < $val(nn)} {incr i} {

set node_($i) [$ns node]

}

# Define node positions and movement model

$node_(0) set X_ 100.0; $node_(0) set Y_ 200.0

$node_(1) set X_ 200.0; $node_(1) set Y_ 300.0

$node_(2) set X_ 300.0; $node_(2) set Y_ 400.0

$node_(3) set X_ 400.0; $node_(3) set Y_ 500.0

$node_(4) set X_ 500.0; $node_(4) set Y_ 600.0

# Initiate proactive path setup from the root node

$ns at 1.0 “$node_(0) initiateProactivePath”

# Set up traffic sources

set udp [new Agent/UDP]

$ns attach-agent $node_(0) $udp

set null [new Agent/Null]

$ns attach-agent $node_(4) $null

$ns connect $udp $null

set cbr [new Application/Traffic/CBR]

$cbr attach-agent $udp

$cbr set packetSize_ 512

$cbr set interval_ 0.1

$cbr start

# Simulation end

$ns at $val(stop) “stop”

$ns at $val(stop) “$ns nam-end-wireless $val(stop)”

$ns at $val(stop) “exit 0”

proc stop {} {

global ns tracefile namfile

$ns flush-trace

close $tracefile

close $namfile

}

# Run the simulation

$ns run

Step 5: Run the Simulation

  1. Store the Tcl script (hwmp_example.tcl).
  2. Open a terminal and navigate to the directory where you logged the Tcl script.
  3. Execute the simulation using the given command:

ns hwmp_example.tcl

Step 6: Analyze the Results

  • Evaluate the HWMP protocol performance, concentrating on metrics like packet delivery ratio, end-to-end delay and routing overhead by using trace files and the network animator (NAM).
  • Inspect how well HWMP manages proactive and on-demand routing in dynamic network scenarios.

Additional Considerations

  • Routing Metrics: Tailor and research with the metrics used for route selection and maintenance in HWMP.
  • Performance Comparison: Assess its efficiency and scalability in mesh network environment by comparing HWMP with other routing protocols like AODV and DSR.

Through this process, we successfully focused and learned about implementation and simulation methods of Hybrid Wireless Mesh Protocol (HWMP) using ns2 simulation tool. If you have any requirement about the samples, we can offer you. Allow us to assist you with a comprehensive performance analysis for your project. If you’re looking to implement the HWMP Protocol in NS2, feel free to reach out to ns2project.com, where we provide you with excellent project topic suggestions.