What is Cisco VIRL/CML?

At last Cisco Live 2014 (Milan) there was a lab on Cisco VIRL/CML. Only one PC located in the Walk-in-lab room were available to start a VIRL lab, and I couldn’t miss that chance to see what exactly VIRL is. The following post is what I could understand using a VIRL/CML installation during the latest Cisco Live 2014 (Milan).

Disclaimer: in this post there are many “facts” and also many personal “guesses”. Things can change, VIRL/CML is not available yet, so everything is evolving.


I can suppose that all readers know what IOU is. By the way let me recap the differences between GNS3, Dynamips, Dynagen, IOU/IOL and iou-web:

  • Dynamips Source Code emulates Cisco routers. That’s mean that Dynamips emulates the hardware so a standard IOS can be executed upon it. Dynamips supports both serial and Ethernet interfaces.
  • Dynagen is a text-based front-end for Dynamips.
  • GNS3: is a graphical front-end for Dynamips.
  • IOU (IOS on Unix) emulates Cisco IOS: it’s an executable files which runs under Sparc/Solaris platform. There is also IOL (IOS on Linux) which runs on x86/Linux platform, and there is should another version which runs on Mac OS platform. IOU supports both serial and Ethernet interfaces. There are also IOU/IOL images which supports a limited subset of Layer 2 features.
  • iou-web is a web front-end for IOL (it should works also on Sparc/Solaris, but I never tested it).
  • XR4U (XR for Unix): it should emulates Cisco IOS-XR on Unix/Linux platform, I never seen it runs.

Cisco VIRL (Virtual Internet Routing Lab) is the old name of Cisco Modeling Lab (CML). It’s a graphical front-end for Cisco virtualized appliances. Currently VIRL supports:

  • Cisco Cloud Services Router 1000V Series: based on IOS-XE it runs 3 GigabitEthernet interfaces and requires about 2Gb of RAM (different versions have different requirements).
  • vIOS: it should requires less resources than CSR1000v, it’s not available for download yet.
  • Cisco IOS XRv: based on IOS-XR it should available for download soon.
  • Ubuntu Linux: it’s a simply Ubuntu Linux Virtual Machine which serves as a server.

All of them are Virtual Machines running x86/x86_64 code.

The main differences between VIRL and IOU are now evident:

  • VIRL is not based on IOU, VIRL needs Virtual Machines;
  • VIRL won’t supports serial interfaces, only Ethernet interfaces will be supported;
  • L2 images are not supported, and maybe they won’t be supported in the future (explained later).

What exactly is Cisco VIRL/CML?

Cisco VIRL/CML is a graphical interface to create and manage labs based on virtual/cloud devices. Technically VIRL/CML is based on:

  • OpenStack and Linux KVM: KVM is the hypervisor who runs Virtual Machines, and OpenStack is the manger.
  • Eclipse; don’t know it’s a Java app or not.
  • Autonetkit: it can automatically allocate IP addresses, configure routing and generate configuration files with templates.

Let’s me clarify: Cisco VIRL/CML is a graphical front-end (like GNS3) which can create labs using x86 images using OpenStack/KVM. It’s faster than Dynamips, more flexible than IOU/IOL, but it supports only L3 Ethernet interfaces. The reason is pretty simple: L2 switches are provided by OpenStack/KVM layer.

My opinion is that L2 interfaces could be supported if a L2 IOS is installed within the OpenStack/KVM suite: like Nexus 1000V is installed within the VMware vSphere suite.

Serial interfaces could be supported also (using classic COM/TTYSx ports), but because VIRL/CML is based on production cloud devices, I suppose we’ll never see L2 or serial interfaces on VIRL/CML.

A good news is that VIRL/CML could support all cloud devices Cisco will make available:

But VIRL/CML could support also:

  • different type of Linux appliances: Ubuntu is already supported;
  • other’s vendor appliances like NetScaler, Imperva, SourceFire…

When VIRL/CML will be released?

Cisco VIRL/CML seems pretty but not completely stable: I can make it crash a couple of time during my test. Rumors say that VIRL/CML will be released not before the end of 2014: someone refers to marketing problems, someone refers to technical problem.

It’s pretty sure that VIRL/CML will be available as OVF/OVA Virtual Machine but also as a bare metal installation (a whole server dedicated to VIRL/CML).

Update (2014-04-29): Cisco Modeling Labs will be released by late Summer 2014:

Q. Is there a hosted or cloud offering? A. No, there is no hosted or cloud offering. Q. How do customers purchase Cisco Modeling Labs? A. The corporate edition will be on the global price list and orderable on the Cisco Commerce Workspace at Cisco.com by late summer 2014.

Update (2014-05-22): Cisco Modeling Labs will be released before the end of July 2014 (Daniel’s blog).