How to Implement ISP Protocols in NS2

To implement the ISP (Internet Service Provider) protocols in ns2, we have to handle network traffic and offer internet services and then make sure the quality of service (QoS) by simulating protocols and features that are often used by ISPs. ISP used protocols may contain BGP (for routing between different autonomous systems), MPLS (for traffic engineering), and QoS protocols for bandwidth management.

Given the difficulty of ISP networks, we will offer a general guide on how you might approach implementing a simplified ISP-like environment in NS2. This has basic BGP-like behavior, traffic shaping, and basic QoS mechanisms.

Step-by-Step Implementation:

Step 1: Define the Scope

State which characteristics of ISP protocols you want to replicate. This could contain:

  • Routing Protocols (BGP): Simulating BGP for inter-domain routing.
  • Traffic Management: Executing traffic shaping or bandwidth management protocols.
  • Quality of Service (QoS): Implementing simplified QoS protocols for prioritizing traffic.

Step 2: Set Up NS2

Make certain that you have installed and configured the NS2. If latest ISP features are needed, you may consider using NS3, which has better support for advanced networking features.

Step 3: Implement Routing and Traffic Management in C++

  1. Implement a BGP-like Protocol

Handle routing amongst autonomous systems by utilizing the BGP protocol used by ISPs. You can execute a basic BGP-like protocol in NS2 that handles route advertisements and route selection.

#include <agent.h>

#include <packet.h>

#include <trace.h>

#include <address.h>

#include <map>

class BGPLikeAgent : public Agent {

public:

BGPLikeAgent();

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

void advertiseRoute(int prefix, int nextHop);

void selectBestRoute(int prefix);

void handleUpdate(Packet* p);

protected:

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

std::map<int, std::vector<int>> bgpTable_; // Prefix -> List of AS paths

};

// Constructor

BGPLikeAgent::BGPLikeAgent() : Agent(PT_UDP) {

// Initialization code here

}

// Packet reception

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

// Handle BGP-like messages (e.g., route updates)

handleUpdate(p);

}

// Advertise a route to peers

void BGPLikeAgent::advertiseRoute(int prefix, int nextHop) {

// Implement route advertisement logic

}

// Select the best route based on BGP attributes

void BGPLikeAgent::selectBestRoute(int prefix) {

// Implement route selection logic based on AS path, etc.

}

// Handle route updates from peers

void BGPLikeAgent::handleUpdate(Packet* p) {

// Process the update message and update the routing table

}

  1. Implement Traffic Management (QoS/Traffic Shaping)

To make sure the QoS, we have to control the flow of data by including traffic management. You can execute a simple traffic management agent that restricts bandwidth or prioritizes particular types of traffic.

#include <agent.h>

#include <packet.h>

#include <trace.h>

#include <address.h>

class TrafficManagementAgent : public Agent {

public:

TrafficManagementAgent();

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

void applyQoS(Packet* p);

protected:

int maxBandwidth_; // Maximum bandwidth in bps

int currentUsage_; // Current bandwidth usage

};

// Constructor

TrafficManagementAgent::TrafficManagementAgent() : Agent(PT_TCP), maxBandwidth_(1000000), currentUsage_(0) {

// Initialization code here

}

// Packet reception

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

applyQoS(p);

}

// Apply QoS policies to the packet

void TrafficManagementAgent::applyQoS(Packet* p) {

// Implement QoS logic (e.g., rate limiting, traffic shaping)

if (currentUsage_ < maxBandwidth_) {

// Forward the packet

currentUsage_ += hdr_cmn::access(p)->size();

send(p, 0);

} else {

// Drop or delay the packet to enforce QoS

drop(p);

}

}

Step 4: Integrate the Protocols into NS2

  1. Modify the Makefile: Include the new BGPLikeAgent and TrafficManagementAgent classes to the NS2 Makefile so that they get compiled with the rest of the simulator.
  2. Recompile NS2:

make clean

make

Step 5: Create a Tcl Script to Simulate an ISP Network

Set up a Tcl script that replicates a network with multiple nodes behaving like ISP routers using your custom protocols.

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 representing ISP routers

set router1 [$ns node]

set router2 [$ns node]

set router3 [$ns node]

# Establish links between routers

$ns duplex-link $router1 $router2 10Mb 10ms DropTail

$ns duplex-link $router2 $router3 10Mb 10ms DropTail

# Attach BGP-like agents to routers

set bgp1 [new Agent/BGPLikeAgent]

set bgp2 [new Agent/BGPLikeAgent]

set bgp3 [new Agent/BGPLikeAgent]

$ns attach-agent $router1 $bgp1

$ns attach-agent $router2 $bgp2

$ns attach-agent $router3 $bgp3

# Set up traffic sources and traffic management

set src [new Agent/TCP]

set sink [new Agent/TCPSink]

$ns attach-agent $router1 $src

$ns attach-agent $router3 $sink

$ns connect $src $sink

# Apply traffic management on router2

set qos [new Agent/TrafficManagementAgent]

$ns attach-agent $router2 $qos

# Start the simulation

$ns at 0.0 “$src start”

$ns at 0.5 “$bgp1 advertiseRoute 10.0.0.0/8 1”

$ns at 0.5 “$bgp2 advertiseRoute 20.0.0.0/8 2”

$ns at 0.5 “$bgp3 advertiseRoute 30.0.0.0/8 3”

$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 6: Run the Simulation

  1. Save the Tcl script (isp_simulation.tcl).
  2. Open a terminal and navigate to the directory where you saved the Tcl script.
  3. Use the below command to execute the simulation:

ns isp_simulation.tcl

Step 7: Analyze the Results

  • Use trace files and the network animator (NAM) to estimate the performance of your ISP network, focusing on routing behavior, QoS enforcement, and traffic management.
  • Test how well your protocols handle route advertisements, traffic shaping, and bandwidth management.

Additional Considerations

  • Scalability: Assess the scalability of your protocols by examining the simulation with more nodes and difficult topologies.
  • Realistic Traffic: Simulate realistic traffic patterns that ISPs would encounter like web traffic, streaming, and file transfers.

In this set up, we had guided you by offering steps and examples of ISP protocols with its implementation and assessments using ns2 tool. For further enhancements, we will present its modern mechanism attachments for your reference.

Implementation of ISP protocols in NS2, along with topic support, is enhanced by ns2project.com. Feel free to reach out to us for the best project outcomes.