Preface
GNS3 is a Graphical Network Simulator that allows the user to run multiple emulated systems including Cisco routers, Juniper routers, Vyatta routers, Linux virtual machines, and Windows virtual machines. Getting GNS3 to actually do this simulation is not always an easy task, especially if you wish to venture beyond a simple network topology.
This book explains exactly what GNS3 does and how to harness that power to build anything from simple CCNA style router simulations to powerful integrated topologies using multiple operating systems across multiple computers.
Topics are covered in a tutorial fashion, so you can work with the author and build your own simulated topologies as you read.
What this book covers
Chapter 1, Clearing the First Hurdle, will take you through the simple installation and post installation tasks required to build your first GNS3 simulation.
Chapter 2, Creating your First GNS3 Simulation,takes you through some important background concepts that will help you get the most out of GNS3, even if you have used GNS3 before, and culminates with a Cisco router simulated network.
Chapter 3, Enhancing GNS3, will explore some of the more advanced features of GNS3, the place to come for help with a particular need, some of which will be prerequisites for later exercises.
Chapter 4, Unleashing Other Emulators, shows you how to use the other GNS3 emulators, Qemu and Oracle Virtual Box and between them how to emulate Cisco ASAs, Juniper Junos routers, Vyatta routers, Linux computers, and Windows computers.
Chapter 5, The Cisco Connection, deals with the routers that are supported by GNS3 and how to find the right iOS with the features you need.
Chapter 6, Peeking under the GNS3 Hood, deals with the internal communications between GNS3, Dynagen, Dynamips, Qemu, and Oracle Virtual Box.
Chapter 7, Tips for Teachers, Troubleshooters, and Team Leaders, shows you how to build a lab with multiple copies of GNS3/Dynamips working together in a variety of ways, along with some detailed troubleshooting tips.
The bonus online chapter, Preparing for Certification using GNS3, will provide tips and exercises that will be useful for you, no matter what level of certification you are going for. This chapter is available at http://www.packtpub.com/sites/default/files/downloads/0809OS_Chapter 8_Preparing_for_Certification_using_GNS3.pdf.
What you need for this book
To complete the examples in this book you will need a computer running Linux, OS X, or Windows, and copies of any operating system required to emulate Cisco routers, Juniper routers, Vyatta routers, Linux virtual machines, or Windows virtual machines.
Note
It is the responsibility of the user to ensure that the devices he/she chooses to emulate have valid software licenses.
You will also need an internet connection to download your copy of GNS3 and any other associated software and scripts as described in the book.
This book was written using computers running Linux Mint Version 15.0 (Cinnamon), OS X Version 10.8.4 (Mountain Lion), and Windows 8.0. The GNS3 version used for development was 0.8.4, with some enhancements not officially seen till Version 0.8.5. Other versions and installation variations may produce slightly different results to those displayed in this book.
Who this book is for
This book is written to assist networking professionals who need to prototype networks, and candidates preparing for their networking exams (for example, CISCO certified exams among others) in getting the best use out of GNS3. This book assumes a good level of competency using computers and basic configuration of the devices that they will simulate.
Conventions
In this book, you will find a number of styles of text that distinguish between different kinds of information. Here are some examples of these styles, and an explanation of their meaning.
Code words in text, IP addresses, folder names, filenames, file extensions, pathnames, and dummy URLs are shown as follows: "After downloading the checkpic.sh script from http://forum.gns3.net/download/file.php?id=2019, store it in your ~/GNS3/Ima ges directory."
A block of code is set as follows:
#!/bin/bash sudo tunctl -t tap0 sudo ifconfig tap0 0.0.0.0 promisc up sudo brctl addbr br0
Any command line input or responses that you need to enter are italicized within text or code blocks, such as:
To configure the Cisco ASA syntax, start with the enable command and use the following as a guide:
ciscoasa> enable Password: <Enter> ciscoasa# configure terminal ciscoasa(config)# interface gigabitEthernet 0 ciscoasa(config-if)# nameif outside
New terms and important words are shown in bold. Words that you see on the screen, in menus or dialog boxes for example, appear in the text like this: "Navigate to File | New Blank Project to reach the New Project dialogue."
Note
Warnings or important notes appear in a box like this.
Tip
Tips and tricks appear like this.
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