CML Now, and VIRL One Day

 In 200-301 V1 CCC No Category on Purpose, Hands-on, News

Cisco has been touting a new network emulation technology for a year or two. The first complete such offering is out now! This post outlines the big ideas, which includes a new commercial product called Cisco Modeling Labs (CML) Corporate Edition, and the one-day-hoped-for Virtual Internet Routing Lab (VIRL). And they are slick!

Emulator, Hypervisor, or Whatever?

The Cisco ecosystem has long included many products that let you experience the IOS CLI for learning. For context, here’s a quick run down:

Simulators: While many definitions exist, simulators generally (a) are software, (b) act like the CLI, (c) may or may not simulate a network behind the CLI that the user sees, and therefore (d) does not require a copy of the Cisco OS whose CLI is being simulated. Many Cisco IOS simulators exist (even one that I helped design). I would put Boson’s NetSim, Cisco’s Packet Tracer, and Pearson’s CCNA Network Simulator in this category.

Emulators: Again, variations on the definition exists, but emulators generally (a) are software, (b) act like hardware well enough so that some Cisco OS can execute within the emulator, so that (c) the user sees the CLI of the real Cisco OS, therefore (d) requiring a copy of the Cisco OS. Cisco has used IOS on Unix (IOU) and IOS on Linux (IOL) emulators internally over the years, for example, using IOL with the CCIE program using IOL for several functions, including the relatively new CCIE Lab Builder. Dynamips and GNS3 both fit into this category as well.

VIRL Family: Cisco has been using the term Virtual Internet Routing Lab (VIRL) in various places in various ways for a while now. I first saw it in action at Cisco Live US, summer of ’13. It is (a) software, that (b) acts as a sort of network hypervisor (think emulator plus Cloud OS, so that (c) the user runs instances of a Cisco OS and sees that CLI of that OS, so that (d) the user requires a copy of the OS. But it’s blessed by Cisco, so you don’t have to illegally use the Cisco OS to use the VIRL tool.


Virtual Internet Routing Lab (VIRL)

Cisco has been talking publicly about this new VIRL option over a year. Cisco has given demos, held Cisco Live sessions, and had open lab sessions using VIRL. It is indeed a wonderful tool. So what does it do? Here are a few features of VIRL as a whole:

  • Design network topologies with a GUI
  • Automatically create the associated configuration based on user GUI input
  • The ability to start/stop a given network (topology) as needed, save state, re-start at the same state or at the initial state
  • A network emulator/hypervisor that spawns VMs to run each instance of a Cisco OS and provide a console CLI to each
  • Support for Cisco OSs other than router IOS
  • Support for host OSs for jump hosts (for testing the network)

For example, say you wanted to experiment and test OSPF and BGP. You could point & click, drag & drop, and make a topology. Answer a few questions, and it creates the IP addressing, OSPF, and BGP configuration commands for you. Boot the topology, creating a virtualized instance of the OS for all the routers. Then change the configurations to match you specific needs, and you’re ready to test!

Overview: CML Corporate Edition and VIRL Lab

Cisco has been talking about VIRL so long though that many have wondered if it would ever make it into the market. Now it has, with one current offering, and one that appears to be on the way in the short term. Both use the same VIRL code as the base code, but one is a commercial product, called Cisco Modeling Labs (CML) Corporate Edition, while the other is (likely) a free option that, as a result, has less to offer. It’s impossible to say how different the two options are until Cisco announces details of both, but figure 1 shows the basic differences.

Figure 1: CML and VIRL Lab

Note that the yet-to-be-released and hopefully free option for VIRL has been referenced by a couple of different names: VIRL Personal Edition and VIRL Lab to name a few. We’ll know the real name once it’s really announced and available!

CML Corporate Edition: The Commercial VIRL

CML Corporate Edition, Cisco’s first commercial offering with VIRL, helps to solve some big needs with corporate test environments. How do you test a new application or design? Do you actually run test scripts against applications, while running in a realistic network? Laughing already about that “realistic network” part of the test? That’s the end game, with practical solutions to the typical problems with maintaining a lab with test gear.

For instance, picture your current test lab: a jumble of old worn out gear, cables who knows where, changed by anyone, and a pain to put together a test environment. Now think forward to a new world: a Cisco server blade or two. Instead of disrupting your buddy’s test to spend time trying to cable the (sometimes missing) gear to meet your needs, you simply start a topology you built with the CML GUI and saved last time you tested. Click for a minute or two to crank up the topology, grab a cup of coffee, and start accessing the CLI of all the devices in your lab pod. Instant test lab, just like last time you needed it, with the same code levels, same topology, same config – it’s a beautiful thing.

You can check out the CML web site for the details, and listen to Cisco’s Craig Brown at the Cisco Champion’s Radio for a Q&A. But here’s a quick list of some of what you get:

  • Product support (Cisco TAC) – bug fixes, new software, help making it work
  • Licensed OS images
  • Support for Cisco IOS, IOS XE, and IOS XR now
  • Support for NX-OS in Beta
  • Support for some kind of layer 2 IOS image (think derivation of IOS for Catalyst switches) is being worked on
  • Multiple users: OS images run on a server; multiple users (clients) can access the test network
  • The CML network can connect to physical networks


CML Costs Money (Oh, man!)

Oh yeah – CML Corporate Edition does cost money. How much? You’ll need a server, VMWare ESXi, and annual licenses for the CML components. Cisco suggests some specific UCS server hardware (because it’s been tested), but even if you get some other cheaper hardware to save some bucks, the CML software annual licenses will be your biggest expense by far. Here’s a sampling:

  • $13,200/year: Base License, which gives you the ability and right to run up to 15 concurrent Cisco OS instances at once. This is the cheapest starting point.
  • $265 – $665/year: The additional license to run multiple IOS XE images (it’s actually the CSR 1000v 10Mbps images)
  • $5000/year: The additional license to run multiple virtualized IOS XR images (called XRv)

So, to run router IOS only, you have at least $13,200/year in license fees to Cisco. (There are discounts for multi-year, so you can reduce the per-year cost, for a larger total cost.) So it’s clearly not in the price range for typical exam self study.

Note: You can find pricing for all the components by chasing the How to Buy link in Cisco’s CML materials.


Closing Comments, Opinions, and What’s Next

In closing for this post: with CML, think about the whole name and emphasize “Corporate”. For companies, especially those companiess that run a mix of Cisco OS types, CML can be a great testing tool, particularly when NX-OS support arrives (which is in Beta). For example: Build a topology with four NX-OS switches, add a few routers to create a WAN, and test access from a branch office to the test network.

As CML matures, it could become the premium test tool for creating the network components in the integration testing phase when using DevOps.

However… CML Corporate Edition is not priced for self-study – that’s where a personal version of VIRL would be nice. More to come on that topic! Any “VIRL for free” is probably where most self-studiers will go. If you just can’t wait for a free VIRL, check out this post that discusses what is basically the predecessor to a free VIRL offering. And I’ll do one more post in this series for now, giving a little more detail on VIRL, and then we’ll discuss it some more if/when there’s a free version from Cisco!

Using Cisco IOS in the All-in-One VM
VIRL Under the Hood in the Dev Innovate Pod
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Shaun Gomez

Great write-up Wendell! For those that want a deeper look into the “guts” take a look at my post on the subject.

Unfortunately, I still don’t have a solid date for VIRL personal on devnet. 🙁


Hey Wendell,
Hope you could remember me (if not as a piece of advice that you had given me on pursuing my CCNPv2, is to watch out for CML and VIRL. And with this post, how do you think CML/VIRL could help me out with the preparation? further I would better go for a free version of Cisco labs.
Looking forward to hear from you regarding preparation for CCNPv2 with VIRL/CML, else we would be pleased, if you create a blog post that would demo how to configure and use CML/VIRL in regarding to CCNPv2, for beginners.

Vivek R

[…] CML Now, VIRL One Day […]


Thank You. Great Summary, very clear.

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