One of my friends sent me this question:

Do you remember if VLANs came first or was it VRFs?

I remember VLANs using ISL (pre-802.1q encapsulation) on early Cisco Ethernet switches (mid 90s), the earliest reference I could track down on Wikipedia is from 1988.

Guess what I found: a software developer trying to persuade his peers that they need an API version of their CLI tool. Yes, I checked and it’s still 2018, and the year CLI dies seems to be a bit further out than some people thought.

I’d guess this proves that the rest of the world is not so far ahead of us lowly network engineers as blabbering pundits and vendor marketers would have us believe.

Needless to say, the engineers architecting Junos knew this almost 20 years ago.

Continuing the series of data center routing protocol podcasts, we sat down with Russ White (of the CCDE fame), author of another proposal: OpenFabric.

As always, we started with the “what’s wrong with what we have right now, like using BGP as a better IGP” question, resulting in “BGP is becoming the trash can of the Internet”.

Here’s another back-to-the-fundamentals question I received a while ago when discussing IPv6 multihoming challenges:

I was wondering why enterprise can’t have dedicated block of IPv6 address and ISPs route the traffic to it. Enterprise shall select the ISP's based on the routing and preferences configured?

Let’s try to analyze where the problem might be. First the no-brainers:

I always love to read the practical advice by Andrew Lerner. Here’s another gem that matches what Brad Hedlund, Dinesh Dutt and myself (plus numerous others) have been saying for ages:

One specific recommendation we make in the research is to “Build a rightsized physical infrastructure by using a leaf/spine design with fixed-form factor switches and 25/100G capable interfaces (that are reverse-compatible with 10G).”

There’s a slight gotcha in that advice: it trades implicit complexity of chassis switches with explicit complexity of fixed-form switches.

A while ago I did an interview about programmable infrastructure that got published as an article in mid-March. As you might expect, my main message was “technology will never save you unless you change your processes to adapt to its benefits.”

Hope you’ll enjoy it!

Got this question from a networking engineer who couldn’t decide whether to go for CCIE Data Center certification or attend my Building Next-Generation Data Center online course:

I am considering pursuing CCIE DC. I found your Next-Generation DC course very interesting. Now I am bit confused trying to decide whether to start with CCIE DC first and then do your course.

You might be in a similar position, so here’s what I told him.

Every second blue moon someone asks me whether they could buy ipSpace.net subscription with PayPal. So far, the answer has been no.

Recently we started testing whether we could use Digital River to solve a few interesting challenges we had in the past, and as they offer PayPal as a payment option, it seemed to be a perfect fit for a low-volume trial.

The only product that you can buy with PayPal during the trial is the standard subscription – just select PayPal as the payment method during the checkout process.

Finally: the first three subscribers using PayPal will get extra 6 months of subscription.

Bruno Wollman pointed me to an excellent article on the ignorance of expertise and confidence of the dumb. Here’s the TL&DR summary (but you should really read the whole thing):

• The expert isn’t always right;
• An expert is far more likely to be right than you are;
• Experts come in many flavors – usually you need a combination of education and expertise;
• In any discussion, you have a positive obligation to learn at least enough to make the conversation possible. University of Google doesn’t count;
• While you’re entitled to have an opinion, having a strong opinion isn’t the same as knowing something.

Enjoy ;)

Here's a trick question: how often do your Visio diagrams match what's really implemented in your network?

Wouldn't it be great to be able to create or modify them on-the-fly based on what's really configured in the network? That's exactly what Anthony Burke demonstrated in the PowerNSX part of PowerShell for Networking Engineers webinar (source code).

You’ll need at least free ipSpace.net subscription to watch the video.

The proponents of the “let’s run EVPN over EBGP underlay” idea often ignore an interesting challenge: EVPN advocates the use of automatically-generated Route Targets, which might not work when every leaf switch uses a different AS number.

I explored this particular can of worms in the EVPN Route Target Considerations section of the Using BGP in a Data Center Leaf-and-Spine Fabric saga.

Remember the IPv6 elephant in the room – the inability to do small-site multihoming without NAT (well, NPT66)? IPv6 is old enough to buy its own beer, but the elephant is still hogging the room. Tons of ideas have been thrown around in IETF (mostly based on source address selection tricks), but none of that spaghetti stuck to the wall.

Stumbled upon this paragraph on Russ White’s blog:

I don’t really know how you write a certification that does not allow someone who has memorized the feature guide to do well. How do you test for protocol theory, and still have a broad enough set of test questions that they cannot be photographed and distributed?

As Russ succinctly explained the problem is two-fold:

One of my readers sent me a container security question after reading the Application Container Security Guide from NIST:

We are considering segregating dev/test/prod environments with bare-metal hardware. I did not find something in the standard concerning this. What should a financial institution do in your opinion?

I am no security expert and know just enough about containers to be dangerous, but there’s a rule that usually works well: use common sense and identify similar scenarios that have already been solved.

I’m always telling network engineers attending my network automation workshops and online courses that there’s no magic bullet or 3-steps-to- success.

You cannot automate a process until you can describe it with enough details so that someone who has absolutely no clue what should be done can execute it.

David Gee published a long (and somewhat ranty) version of that statement. Enjoy!