I have been wanting to get a little deeper into some various technologies surrounding MPLS and BGP-based VPNs (beyond basic L3VPN, such L2VPN, QoS, multicast, EVPN, etc.), so I assembled a virtual lab with approximately 30 routers which represent a service provider core and several “customer” sites, along with two sources of fake Internet connectivity (or more accurately, a simulated Default-Free Zone (DFZ)). After I earn a deeper understanding of topics within a single service provider core, I will expand this to inter-provider topics. Yes, I meant “earn”, since more work will be involved beyond just reading.
I was getting ready to develop an IP addressing scheme for the core network, and I realized I have a good opportunity here to get deeper into network automation. While studying for the CCIE R&S lab, I spend quite a lot of time in a text editor building configurations to review before pasting them into the device consoles. For tasks that involve repetitive configurations, copy-and-paste is my friend. You don’t (yet) have access to anything like Python or Ansible in the CCIE R&S lab to try to automate things (though I suppose you could use TCL if you really wanted to).
A good portion of setting up a large lab environment of any kind is developing and applying the baseline configuration. I’ve done this countless times over the years, and I was getting ready to do it yet again when it occurred to me that if I invest some time now to develop and use some network automation processes, the buildup and teardown of future labs will be so much quicker. I’ve dabbled with this in the past; I learned the basics of Python and have developed a few network-oriented scripts. I found I enjoy working through the logic and seeing the working results. I also developed and deployed a simple Ansible script to push out some configurations on my current production network.
I read the mostly-complete “rough cuts” version of Network Programmability and Automation by Jason Edelman, Matt Oswalt, and Scott Lowe. This is a really fantastic book, and along with Russ White and Ethan Banks‘ new book, I consider it an absolute must-read for anyone wishing to progress their career in computer networking and establish a very strong set of foundational knowledge (I swear I’m not trying to name-drop, but I’ve read a LOT of networking books, and these really are toward the top of the list). When I read Network Programmability and Automation the first time, I used the knowledge as an overview of some of the things that are possible within the realm of network automation. Now I’m going through it again to develop the skills necessary to automate the deployment of my lab configurations.
One thing I believe hinders many people wanting to dig deeper into automation (myself included), is having a use case. It’s easy enough to say that if you have to do a single task more than once, you should automate it. Automate all the things, right? There are two issues I see here: the underlying knowledge of what it is you’re trying to automate, and the ability to evaluate the “bigger picture”.
For example, within the context of networking, you could learn how to automate the deployment of complex configurations for a particular routing protocol, but what good is that going to do if you don’t fully understand what those configurations mean? Automation presents you with an opportunity to make mistakes much faster, and on a much more grand scale. If you automate configurations among several devices and things end up not working as anticipated, can you troubleshoot what went wrong?
Likewise, evaluating the bigger picture helps to understand where particular forms of automation are helpful, and where you will run into diminishing returns. For example, you could automate just about every process involved in network configuration, but nearly every business is going to have exceptions that need to be handled somehow, and automation may not be the answer in those instances.
Tying both of these concepts together, I realized the opportunity to automate the things I know extremely well due to my previous knowledge and experience, such as baseline configurations involving hostnames, IP addresses, basic routing protocol configuration, etc. Because I know how all of these things work very well, I can easily automate this as well as troubleshoot potential issues if things don’t go as expected. In the bigger picture aspect, the purpose of the lab is for me to understand other topics that use the baseline configuration as a prerequisite, and therefore I am not yet ready to automate those technologies because I do not yet have a full understanding of their nuances.
In other words, the more you learn, the more you can automate. You need to develop skills on how to automate things, but if you automate things you do not understand, you are setting yourself up for future frustration. Don’t let this discourage you from learning and getting deeper into both automation and classical network engineering skills. Increasingly, the two go hand-in-hand, but you can certainly end up in a chicken-or-the-egg scenario. My advice is to “earn” the networking skills first, and automate them second.