Book Image

GNS3 Network Simulation Guide

Book Image

GNS3 Network Simulation Guide

Overview of this book

GNS3 is an open-source Graphical Network Simulator used extensively by networking professionals to simulate networking devices such as Cisco, Juniper and Vyatta routers, along with Virtual PCs. GNS3 Network Simulation Guide gives you all the information you need to run a successful GNS3 simulation. You will be guided through the tricky installation pre-requisites and procedures involved in developing a simulated topology suitable for studying for Cisco CCIE Certification. We will also cover many useful tips and tricks which will help you make the most of your GNS3 simulator application. You will begin the GNS3 journey by ensuring that you have prepared your computer with any additional files required by GNS3, to set up the simulated environment needed for a successful installation process. Once GNS3 is installed, you will get to work creating a successful simulation including routers, Ethernet switches, Virtual PCs, and capture packets using Wireshark. Next, you will learn how to master GNS3's Graphical User Interface as well as the Command Console. The inner workings of GNS3 are described in depth so that you gain an appreciation of how UDP tunnels are used to tie the many components of GNS3 together. By following the clear examples and exercises in this guide, you will learn everything that you need to know about how to use GNS3 to prepare for certifications, as well as simulate real-world network scenarios.
Table of Contents (14 chapters)
GNS3 Network Simulation Guide
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

GNS3 Limitations


This preceding design was created in part to overcome the inability for a host computer to be able to communicate with a guest router. However there are some other limitations that you should be aware of as well.

Ethernet interfaces are always up

On a normal physical network, the state of a point-to-point Ethernet interface is dependent on the state of the other end. If one end is shut down or unplugged, the other end is also in a down state. This has implications for routing fail-over scenarios as well as other protocol-timeouts.

In GNS3/Dynamips, if one end of a point-to-point Ethernet link is shut down, it has no effect on the other end. Your topology will be dependent on protocol timeouts or you will need to configure SLAs to trigger fail-over scenarios.

In fact, even if no cable is attached to an Ethernet interface, it will remain in an up state from the moment the no shutdown command is issued.

This means that if you want to test fail-over scenarios on GNS3 in the same...