GNS3 is an open-source software that allows the user to simulate large and complex networks by emulating physical devices, routers and switches from multiple vendors.
It has a GUI (graphical user interface) that eases the usage and runs on x86 hardware and on multiple operating systems, including Linux, Windows and Mac OS.
Based on the type of devices you want to use, different tools will be needed on your computer along with GNS3.
In most cases, GNS3 is used to simulate networks with Cisco devices. To do so, you will need Dynamips, the Cisco IOS emulator.
GNS3 is used by engineers that are pursuing different Cisco certifications. With few limitations related to switching, one can use GNS3 to prepare for all levels of Cisco certification for the routing and switching track, including CCIE.
Right now, Intense School offers a wide variety of GNS3 labs that covers different topics, mostly covering topics from the CCNA Routing and Switching exams. A few others cover some interesting technologies used in service provider environment.
The purpose of this article is to group and arrange all the GNS3 labs in a way that could help students to prepare better for the certifications they are pursuing. Bookmark this page, and come back regularly during your studies.
The GNS3 labs are split in two major categories: CCNA R&S topics and CCNP/CCIE R&S topics.
Before you can start using GNS3, you need to install it and configure it on your computer. This article will guide you through the installation and configuration: GNS3 Labs for CCNA: Getting Started. As you can see, this article doesn’t fall specifically to any of the two categories mentioned above; in other words, it can be part of both categories. The article is an extensive one and walks you step-by-step through the installation and your first GNS3 lab.
For the CCNA R&S topics, I arranged all the labs following the two books content written by Wendell Odom, which are reviewed for you at the following links: CCNA ICND1 100-101 and CCNA ICND 2 200-101. The reason for doing this is so you can practice while you are going through the book. The content of the books follow a logical progress and makes sense to arrange the GNS3 labs in the same way.
The first step after you access your devices would be to configure users and passwords and the method by which the authentication will be performed on the devices.
This chapter from ICND1 (Part II: “Ethernet LANs and Switches” / Chapter 8: “Configuring Ethernet Switching”) talks about the features in common with routers; one of them is securing access to the devices. You can practice in GNS3 how to configure AAA using Radius authentication by following this article: Using Linux Tools with Cisco Devices for Access Control.
One very common feature deployed on routers is to configure DHCP. DHCP is covered in ICND1 (Part IV: “Implementing IP Version 4” / Chapter 18: “Configuring and Verifying Host Connectivity”). You can practice this using GNS3 by following this article: GNS3 Labs for CCNA: DHCP Server Configuration and Verification.
The ICND1 book takes us further and discusses security. In these two chapters (Part VI: “IPv4 Services” / Chapter 22: “Basic IPv4 Access Control Lists” and Part VI: “IPv4 Services” / Chapter 23: “Advanced IPv4 ACLs and Device Security”), Access Control Lists (ACL) are explained in detail. There are two GNS3 labs covering these two chapters: GNS3 Labs for CCNA: Basic Access Control Lists and GNS3 Labs for CCNA: Advanced Access Control Lists.
While still going through the ICND1 book, you will learn about Network Address Translation, or NAT. Once you are done with the reading, you can start GNS3 and practice NAT using this article: GNS3 Labs for CCNA: Basic NAT (Network Address Translation).
This is the complete list of articles that cover ICND1 book topics. Once you begin studying more advanced topics in ICND2, you will have other GNS3 labs that you can practice.
Just as you start the ICND2 book, you will be flooded with information about Spanning Tree. Part I: “LAN Switching” / Chapter 2: “Spanning Tree Protocol Implementation” covers the configuration. You can practice STP using this lab: GNS3 Labs for CCNA: STP Configuration and Verification.
Other common features deployed in a LAN are first hop redundancy protocols. Among others, they are HSRP and GLBP. There is one chapter in ICND2 covering these two protocols (Part II: “IP Version 4 Routing” / Chapter 6: “Creating Redundant First-Hop Routers”). Once you get familiar with the concepts, you can practice HSRP and GLBP in GNS3. Use these two articles to do it: GNS3 Labs for CCNA: HSRP Configuration and Verification and GNS3 Labs for CCNA: GLBP Configuration and Verification.
The next chapter from ICND2 (Part II: “IP Version 4 Routing” / Chapter 7: “Virtual Private Networks”) discusses VPN technologies. Generic Routing Encapsulation is a topic for the CCNA exam; you can practice the GRE configuration in GNS3, using this article as a reference: GNS3 Labs for CCNA: GRE Tunnels Configuration and Verification.
As you move along with your study, inevitably you will reach the point where routing protocols configuration and troubleshooting are discussed. In ICND2, these are OSPF (Part III: “IP Version 4 Routing Protocols” / Chapter 8: “Implementing OSPF for IPv4”) and EIGRP(Part III: “IP Version 4 Routing Protocols” / Chapter 10: “Implementing EIGRP for IPv4”).
There are three articles that can give you hands-on experience using GNS3 with regards to OSPF and EIGRP. There are: GNS3 Lab: Troubleshoot and Resolve Routing Issues — OSPF, GNS3 Labs for CCNA: EIGRP Configuration and Verification and GNS3 Lab: Troubleshoot and Resolve Routing Issues – EIGRP.
If you’ve reached the Wide Area Network chapter and you would like to practice PPP (Part IV: “Wide Area Networks” / Chapter 12: “Implementing Point-to-Point WANs”), you are in luck. This article provides hands-on instructions on PPP: GNS3 Labs for CCNA: Configuring PPP.
The last two GNS3 articles that covers CCNA R&S topics are related to SNMP and Netflow. These two topics match one of the last chapters of ICND2 book, Part VI: “Network Management” / Chapter 19: “Managing Network Devices.” These topics can be practiced using these GNS3 labs: Network Management Labs in GNS3 – Part 1 and Network Management Labs in GNS3 – Part 2.
And this is it for CCNA R&S GNS3 labs. At the same time, you’ve also reached the end of the ICND2 book.
Now, it’s time to discuss the GNS3 labs for CCNP/CCIE R&S topics.
As a candidate for CCNP or CCIE certification, you will need to understand how routing protocols are working and how you can resolve routing problems. Border Gateway Protocol (BGP) is not covered by CCNA R&S topics, but you can get familiar with its operation by following these two articles: BGP Weight, Local Preference, and MED and GNS3 Lab: Troubleshoot and Resolve Routing Issues — BGP.
Also, protocol independent troubleshooting techniques are discussed in this article: GNS3 Lab: Troubleshoot and Resolve Route Filtering Issues.
For CCIE R&S exam, there are a few advanced topics regarding Multiprotocol Label Switching (MPLS). MPLS is covered in great detail by the CCIE Service Provider exam topics.
For the CCIE R&S exam; however, this topic is covered, let’s say, briefly (compared to the CCIE SP exam). However, there are three articles that cover the topics for CCIE R&S exam. These three articles that you can use to practice MPLS using GNS3 are: GNS3 Lab: Introduction to MPLS Layer 3 VPN Part 1, GNS3 Lab: Introduction to MPLS Layer 3 VPN Part 2 and GNS3 Lab: MPLS Layer 2 VPM AToM.
Another topic found in the CCIE R&S exam topics is Dynamic Multipoint Virtual Private Network (DMVPN). You can get a glimpse of DMVPN and practice it using GNS3 by following this article: GNS3 Lab: Introduction to DMVPN.
And these are all the articles that fall in the CCNP/CCIE topics.
As you can see, a lot of the CCNA R&S topics that you can find in the two books mentioned in the beginning of the article can be practiced in GNS3. And more importantly, you don’t have to start from scratch. You can download the labs from the Intense School website.
I hope you will find this is a good summary and a logical one and I wish you happy labbing…you’ve got some work to do!