How to Practice Configuring Routers and Switches

For concert pianists and network administrators alike, practice makes perfect. Certified Cisco Instructor, Mark Sabo, explores the best ways to hone your routing & switching skills.

Ways to Configure Routers and Switches

One of the most common questions my students ask is, “What can I do to get more practice configuring routers and switches?” The best thing you can do is to go out and get some real equipment and build your own lab environment. Nothing beats having real equipment to touch, smell and practice with. You can find cheap routers and switches on the internet; eBay is the most popular place where people go to unload their old equipment for dirt cheap instead of trashing it. You don’t need new, expensive equipment for a home practice lab, and this presents the best opportunity. For those of us who don’t want to spend money on a practice lab, or want the flexibility of playing with routers wherever we are, there's GNS3.

GNS3 is an amazing network simulator and its uses are extensive.

GNS3 - short for "Graphical Network Simulator" - is an open-source network emulator. It can emulate an entire network! It’s not like some of the router simulators that you find on the internet, which are mostly just programs written to respond like a router would, but are buggy and don’t include a full command set. GNS3 emulates an entire router with a full IOS (Internetwork Operating System) command set. It’s virtualization, but for a routing infrastructure. You do however need to get your hands on an IOS image (these are licensed so be careful about violating any license agreements when using), but once you have an IOS, load it into GNS3 and it will emulate the entire IOS. Every command and feature is available to you just as if you had the physical router. You can then use your virtual router to build entire virtual networks, ranging from simple to complex topologies. You can take it even further by setting up VMs (virtual machines) on your computer and using GNS3 to route between them. You can have GNS3 communicate with your host computer as well and actually use your host machine to ping and telnet around your topology - all from your host machine or from other VMs! The routers in GNS3 can also be configured through the CCP (Cisco Configuration Professional), which is a GUI program that can be used to configure your equipment instead of using the command line terminal. GNS3 is an amazing program and its uses are extensive.

One of the limitations of GNS3 is that it doesn't emulate switches; it only does routers. There are switches in the program, but they are generic switches, not running a full IOS that you can completely configure. You can however add switching modules to the routers GNS3 is emulating, so you can setup a switch type of configuration, it’s just not a dedicated full switch you're creating. So if you're really looking to practice hardcore layer2/3 switch configurations, you may still need to go out and get one of those eBay switches, but I think the switching module should do the trick for most people. At first glance GNS3 isn’t the easiest program to figure out how to use either. It will take some time to get used to, especially if you are trying to build complex topologies or route between VMs. Take that time though and go through the tutorials on their website, watch the videos and browse YouTube for other users' explanations & tips. This research will be worth it in the long run as you learn to build the ideal virtual lab for all your networking practice needs.

So to answer the question, “What can I do to get more practice configuring routers and switches?” go out and build yourself a practice lab and get cracking. Whether you invest a little money and build a lab with physical equipment or you go the virtual route (no pun intended) with GNS3, you won’t be disappointed as you discover all sorts of cool things you can do to advance your networking skills. So get building, get practicing and good luck, but most of all have fun!

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