The first car I got decades ago was a simple mechanical beast – you’d push something, and a cable would make sure something else moved somewhere. I could also fix 80% of the problems, and people who were willing to change spark plugs and similar stuff could get to 90+%.

Today the cars are distributed computer systems that nobody can fix once they get a quirk that is not discoverable with level-1 diagnostic tools.

Years ago, I decided to try out another idea: solving real-life challenges with the help of an easy-to-consume online consulting service. When I discussed the idea with my friends during one of the early Networking Field Day events the opinion was pretty unanimous: “this will never work”

Fortunately, they were wrong. Not only did ~100 customers decided to use it in the meantime, the simple idea grew to a point where I couldn’t do it all on my own.

Tiziano Tofoni wrote a lengthy comment on my EVPN in small data center fabrics blog post continuing the excellent discussion we started over a beer last October. Today, I’ll address the first part:

I think that EVPN is an excellent standard for those who love Layer 2 (L2) services; we may say that it is an evolution of the implementation of the VPLS service, which addresses some limits in the original standard (RFCs 4761 and 4762).

I might be missing something, but in my opinion, there’s no similarity between EVPN and VPLS (apart from the fact that they’re trying to solve the same problem).

I always encourage the students attending the Building Network Automation Solutions online course to create solutions for problems they’re facing in their networks instead of wasting time with vanilla hands-on assignments.

Francois Herbet took the advice literally and decided to create a solution that would configure PE-routers and create full-blown device configurations for CE-routers.

From the fantastic Lines, Radios and Cables (a MUST READ if you’re even remotely interested in this thing called latency):

When we put different colours of light, or wavelengths, onto a single fibre, we call it Wave Division Multiplexing (WDM) which is a complicated way of saying a pretty rainbow […] International trading is powered by rainbows, literally.

One of the beauties of VMware NSX is that it’s fully API-based – you can automate any aspect of it by writing a script (or using any of the network automation tools) that executes a series of well-defined (and well-documented) API calls.

To make that task even easier, VMware released PowerNSX, an open-source library of PowerShell commandlets that abstract the internal details of NSX API and give you an easy-to-use interface (assuming you use PowerShell as your automation tool).

One of my readers wanted to know more about containers and wondered how ipSpace.net materials could help him. Here’s a short step-by-step guide:

I published this blog post to help ipSpace.net subscribers navigate through Docker- and containers-related material. You might want to skip it if you’re not one of them.

Gabriel Sulbaran decided to tackle a pretty challenging problem after watching my Ansible for Networking Engineers webinar: configuring older Checkpoint firewalls.

I had no idea what Ansible was when I started your webinar, and now I already did a really simple but helpful playbook to automate changing the timezone and adding and deleting admin users in a Checkpoint firewall using the command and raw modules. Had to use those modules because there are no official Checkpoint module for the version I'm working on (R77.30).

Did you automate something in your network? Let me know!

I had an interesting “how do you build a small fabric without throwing every technology in the mix” discussion with Nicola Modena and mentioned that I don’t see a reason to use EVPN in fabrics with just a few switches. He disagreed and gave me a few good scenarios where EVPN might be handy. Before discussing them let’s establish a baseline.

The Setup

Assume you’re building two small data center fabrics (small because you have only a few hundred VMs and two because of redundancy and IT auditors).

A while ago Russ White (answering a reader question) mentioned some areas where we might find machine learning useful in networking:

If we are talking about the overlay, or traffic engineering, or even quality of service, I think we will see a rising trend towards using machine learning in network environments to help solve those problems. I am not convinced machine learning can solve these problems, in the sense of leaving humans out of the loop, but humans could set the parameters up, let the neural network learn the flows, and then let the machine adjust things over time. I tend to think this kind of work will be pretty narrow for a long time to come.

Guess what: as fancy as it sounds, we don’t need machine learning to solve those problems.

I don’t think I’ve ever been at a Tech Field Day event that’s been as intense as what we went through in the last few days at Cisco Live Europe – at least 17 different presentations in two days. It’s still all a blur and will take a long while to sort out.

First impressions:

Although it’s almost three months till the start of the Building Next-Generation Data Center online course, we already have most of the guest speakers. Today I’d like to introduce the first two (although they need no introduction).

You might have heard about Russ White. He was known as Mr. CCDE when that program started and recently focused more on data centers, open networking and whitebox switching. He’s also an authority on good network design and architecture, network complexity, and tradeoffs you have to make when designing a network.

Got an interesting set of questions from one of my readers. He started with:

I really like networks but I don't know if I am doing enough for this community. Most of my work is involved with technologies which are already discovered by people and I am not really satisfied with it.

Well, first you want to decide whether you want to be (primarily) a researcher (focusing on discovering new stuff), an engineer (mostly figuring out how to build useful things by using existing stuff), or an administrator (configuring stuff).

Regardless of how much I write about (the ridiculousness of using) stretched VLANs, I keep getting questions along the same lines. This time it’s:

What type of applications require L2 Extension and L3 extension?

I don’t think I’ve seen anyone use L3 extension (after all, isn’t that what Internet is all about), so let’s focus on the first one.

Stretched VLANs (or L2 extensions) are used to solve a number of unrelated problems, because once a vendor sold you a hammer everything starts looking like a nail, and once you get used to replacing everything with nails, you want to use them in all possible environments, including public and hybrid clouds.

It took years after NETCONF RFCs were published before IETF standardized YANG. It took another half-decade before they could agree on how to enable or disable an interface, set interface description, or read interface counters. A few more years passed by, and finally some vendors implemented some of the IETF or OpenConfig YANG data models (with one notable exception).

Now that we have the standardized structure, it’s easy to build automated multi-vendor networks, right? Not so fast…