Image of Jeremy L. Gaddis, CCNA, CCNP (and Cortney, in case you were wondering)

Cisco IOU

by Jeremy L. Gaddis

“Cisco Learning Labs go beyond the Cisco simulator Packet Tracer by enabling virtual access to actual CCNA, CCNP, and CCIP practice lab bundles that are powered by Cisco IOS Software on UNIX. For the first time, Cisco labs are available for both routing and core switching features, giving you the practical experience that is desired to boost your knowledge and confidence before taking your Cisco certification exam.”

What’s IOU?

Cisco Learning Labs are online labs “powered by” Cisco IOS on Unix (IOU), which you probably haven’t heard of before if you’re new to the world of Cisco — or maybe even if you’re not!

“IOS on Unix (IOU) is a fully working version of IOS that runs as a user mode UNIX (Solaris) process. IOU is built as a native Solaris image and run just like any other program. IOU supports all platform independent protocols and features.”

Cisco IOS is the software (think “operating system”) used on many of Cisco’s routers and switches, especially the ones you’ll be working with as you progress towards the CCNA. Cisco simply compiles the same IOS code to run on Unix operating systems (Solaris, Linux, OS X, and perhaps others) for use by Cisco engineers and some lucky customers.

For many years, Cisco IOU was highly protected and obtaining a copy was extremely difficult and only possible in very limited circumstances. In September 2010, on my flight home from the Net Field Day event, I ended up sitting next to a Cisco employee who “forgot” a USB drive (with the Cisco IOU software on it) in his seat as he exited the plane. Several months later, after it started showing up on BitTorrent sites, I wrote up the Cisco IOU FAQ in order to help others use the software.

Why Would I Use IOU?

In an ideal world, we’d all home a rack full of Cisco routers and switches at home to practice on (and free electricity!). Unfortunately, that’s simply not possible for everyone. For those aren’t lucky enough to have a home Cisco lab, IOU presents a great alternative.

One of the biggest advantages of Cisco IOU is that you can run many “virtual routers” on a standard PC running Linux. To illustrate, I have had 100 virtual routers running simultaneously on a single Pentium 4 class PC. You can emulate entire enterprise networks on a standard computer, with nearly full functionality. The primary features that aren’t supported are voice functionality, quality-of-service, and configuration registers. There are also some issues when using redundant links between virtual switches.

Back in April 2011, a few months after IOU “leaked” onto the Internet, the Cisco Learning Labs became available. To get a quick overview, check out the presentation slides posted by Greg Ferro of the Packet Pushers podcast. In addition, Jeremy Stretch wrote up A Review of Cisco’s New Learning Labs and Brandon Carroll created the Quick Look at The Cisco Learning Network Learning Labs video, which you can watch below.

I’m using Cisco IOU extensively for the lab exercises here on the web site. There are, however, some things that don’t work very well on IOU and in those cases I’ll be using my home Cisco lab. Check out the Free CCNA Labs Topology page to see the actual network topology I’m using in IOU.

Where Can I Get IOU?

It’s quite possible that you can find the IOU software available on various Internet sites but, as far as I’m aware, no one has been creating labs based on it. For that, you may have to shell out some cash for the Learning Labs.

IOU Licensing

I have posted a video which provides an educational look into the Cisco IOU Licensing.