How to Implement EGP Protocol in NS2

 

To implement the Exterior Gateway Protocol (EGP) like BGP (Border Gateway Protocol) in NS2 (Network Simulator 2) encompasses a custom execution due to ns2 can’t support EGPs. This protocol is used to direct traffic amongst various autonomous systems (ASes) in larger networks like Internet. The task is more difficult than executing basic protocols like RIP or OSPF because BGP includes path-vector routing, policy-based routing and maintaining a full routing table of network prefixes.

Follow the general approach to implementing an EGP in NS2, aiming on BGP as an example:

Step-by-Step Implementation:

Step 1: Understand the Protocol

Before initiating BGP or any EGP in NS2, you should understand how the protocol functions containing concepts like path-vector routing, systemized systems, route advertisements, and policy-based routing.

Step 2: Set Up NS2

Make sure that you have installed and configured the ns2 properly on your computer by following website’s installation instructions particular to your operating system.

Step 3: Extend NS2 for BGP Support

We need to expand the NS2’s potential due to the BGP lacks the support for NS2. This commonly involves:

  1. Custom C++ Module: Execute the BGP-like mechanisms by writing a custom C++ module.
  2. Tcl Scripting: Developing your simulation using Tcl scripts to replicate BGP behavior amongst various autonomous systems (ASes).

Step 4: Create a Custom C++ Module for BGP

Manage the BGP operations by creating a new C++ module. The module should:

  • Handle BGP Peering: Accomplish sessions amongst BGP routers in various ASes.
  • Exchange Routes: Execute the logic for interchanging route advertisements amongst BGP peers.
  • Maintain Routing Tables: Preserve the best routes and manage updates as routes vary.
  • Implement Policies: Allow for policy-based routing, where particular routes are chosen over others according to the predefined criteria.

Here’s a brief overview of the steps contains:

  1. Create a New C++ Class: Generate a new C++ class for your BGP router.
  2. Implement BGP State Machine: Execute the BGP state machine (Idle, Connect, Active, OpenSent, OpenConfirm, Established).
  3. Handle Route Advertisements: Deliver and obtain BGP updates by executing techniques.
  4. Route Selection: Implement the BGP route selection algorithm (such as picking routes as per its AS path length).

Example code for a basic BGP class (in C++) might look like:

#include <agent.h>

#include <packet.h>

#include <iostream>

class BGPAgent : public Agent {

public:

BGPAgent() : Agent(PT_TCP) {

// Initialize BGP state

}

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

// Handle incoming BGP packets

}

void sendBGPUpdate() {

// Send BGP update messages to peers

}

void establishBGPConnection() {

// Handle the BGP connection establishment process

}

void selectBestRoute() {

// Implement route selection based on BGP policies

}

};

// Register the BGP agent with NS2

static class BGPClass : public TclClass {

public:

BGPClass() : TclClass(“Agent/BGP”) {}

TclObject* create(int, const char*const*) {

return (new BGPAgent());

}

} class_bgp;

Step 5: Integrate BGP into Your NS2 Simulation

  1. Modify the Makefile: Alter the Makefile and recompile NS2 to make certain that your new BGP class is compiled with NS2.
  2. Create a Tcl Script for the Simulation: Configure your network topology using Tcl, stating numerous autonomous systems and BGP routers.

Example Tcl Script:

# Create the simulator object

set ns [new Simulator]

# Define nodes in different ASes

set AS1_Router [$ns node]

set AS2_Router [$ns node]

set AS3_Router [$ns node]

# Establish links between routers in different ASes

$ns duplex-link $AS1_Router $AS2_Router 1Mb 10ms DropTail

$ns duplex-link $AS2_Router $AS3_Router 1Mb 10ms DropTail

# Attach BGP agents to routers

set bgp1 [new Agent/BGP]

$ns attach-agent $AS1_Router $bgp1

set bgp2 [new Agent/BGP]

$ns attach-agent $AS2_Router $bgp2

set bgp3 [new Agent/BGP]

$ns attach-agent $AS3_Router $bgp3

# Establish BGP peering sessions

$bgp1 establishBGPConnection

$bgp2 establishBGPConnection

$bgp3 establishBGPConnection

# Run the simulation

$ns run

Step 6: Run the Simulation

  1. Compile the Modified NS2: If you made alterations to the NS2 source code (for instance, attaching a BGP class), recompile NS2.

make clean

make

  1. Run the Simulation:

ns bgp_simulation.tcl

Step 7: Analyze Results

  • Check BGP Updates: Make certain that BGP updates are being delivered and received properly.
  • Routing Tables: Confirm that routing tables are updated as per BGP operations.
  • Trace Files: Estimate trace files to monitor BGP behavior and network performance.

Additional Considerations

  • Complexity: Executing BGP is advance due to the demand to handle BGP sessions, manage route advertisements, and accomplish policy-based routing.
  • Testing: Make certain the precision by thoroughly examining the execution with various network topologies and policies.
  • Using NS3: If NS2 becomes too restricting, consider utilizing NS3, which has better support for extreme routing protocols and more advanced networking mechanisms.

In this manual, we encompass example with their execution process and how to extend them using ns2 tool. We established the Exterior Gateway Protocol through this set up. We will deliver any other details on this implementation, if needed. You can receive personalized support from our team as we guide you in implementing the EGP Protocol in NS2. Feel free to reach out to ns2project.com, where we are ready to assist you with innovative ideas and topics.