Cisco Modelling Labs

I have been running up various labs for work, generally to test a feature or investigate a certain issue, and have found my desire to do any discretionary tinkering has decreased somewhat. When I’m not doing that I find I have to learn something new or occasionally relearn something old. (I think I have now forgotten more than I know)

To this end, I recently started working through a Cisco ENCOR 350-401 course with no intention of taking the exam, but just to brush up on some networking fundamentals:

https://www.udemy.com/course/cisco-encor/.

It is a very good course and I recommend it. It also has labs which come in the form of yaml files you can import into Cisco Modelling Labs (CML). I didn’t have CML but there was a sale on so I decided to make the investment (which is fairly substantial: $200-ish) and give it a go.

I had tried it in a previous incarnation when it was VIRL and I gave up on that when I realised I was spending more time troubleshooting VIRL than I was learning networking. The updated product is much improved.

You install CML as a VM with an attached refplat ISO ‘disk’ which contains all the network images you need and this can be downloaded from the same place you get the CML download. I don’t remember this requirement being especially clear (though I can be guilty of skimming installation instructions). However, here I would read them carefully, make sure you have the ISO disk attached to your VM and modify your VM’s settings in line with the given recommendations before starting it.

Also I found Nexus switches don’t work on the ‘gold star’ 2.7 CML version (you get no console) but do work on the cutting edge 2.8 version. Also you need a fairly beefy machine – I have a NUC with 64GB of RAM and VMware Workstation Pro 16. (Apparently, this is now free for personal use)

What I liked about CML is that my original use-case did actually work: I imported the yaml files from the course and had a lab up and ready. I am always surprised when something actually works as advertised! Also, the labs seemed to start reasonably quickly – though the Nexus behemoths take a while go come up. I did try Nexus switches on GNS3 but never really got them stable and I needed to lab with these so I guess that was another use-case. Another advantage with CML is you get all the Cisco images:

https://developer.cisco.com/docs/modeling-labs/vm-images-for-cml-labs

…which is obviously not the case with GNS3 or EVE-NG. The CML GUI (which is accessed through a browser) was pretty intuitive and easy to pick up.

Disadvantages are I guess that is not designed to integrate with non-Cisco images. It’s probably possible but I can’t see it being as easy as in GNS3, and it is an investment.

I think my CML VM is going to get a fair bit of use…after years spent at Layer 3 / 4 with firewalls, proxies, and WAFs, circumstance find me playing with Nexus switches and trying to get my head round vPC. I will possibly post on this later for any die-hard readers eager for a proper lab-based post.