With the recent plethora of overlay networking startups and Cisco Live Dynamic Fabric Architecture announcements it’s time to revisit a blog post I wrote a bit more than a year ago, comparing virtual networks and voice technologies.

They say a picture is worth a thousand words – here are a few slides from my Interop 2013 Overlay Virtual Networking Explained presentation.

The last part of the ProgrammableFlow webinar described typical use cases including Cloud-as-an-Appliance, traffic steering (used by appliances like Radware DefenseFlow) and hypervisor switching with PF1000. Predictably, the use cases were followed by a lengthy Q&A session.

Continuing from the previous Tools That I Use post, here’s what I’m using to generate the hand drawings in blog posts and case studies.

Wacom Cintiq with SketchBook Pro has been indispensable for high-resolution drawings I used in case studies. I’ve tried to import router symbols in SketchBook Pro and make them look like they would be hand-drawn, but my illustrating skills are almost non-existent.

SketchBook Pro is an overkill for low-resolution blog post drawings … and it forces me to sit down with my computer, so I prefer to draw all other diagrams on an iPad. My fingers are way too clumsy and fat (supposedly rock climbing helps to make them oversized), so I’m relying on Apple Pencil to get some reasonable precision.

Paper 53 was my favorite drawing program, particularly due to its interesting brush-resembling strokes, but they stopped enhancing it years ago (or so it seems), so I switched to Procreate.

Procreate allows me to import icons, duplicate them, place them onto a grid, use layers… close to ideal for what I need.

Getting the drawings from the iPad to the laptop where I do all my writing has been a royal pain (the best I could do was sending them via email). Situation got way better in recent years, with most drawing programs being able to save individual images directly to Dropbox … where they miraculously appear on my laptop ready to be published in a blog post.

Priceless! (source: Dilbert.com)

Nicolas Vermandé sent me a really interesting question: “I've been looking for answers to a simple question that even different people at Cisco don't seem to agree on: Is it a good idea to class IP traffic (iSCSI or NFS over TCP) in pause no-drop class? What is the impact of having both pauses and TCP sliding windows at the same time?”

One of the significant challenges of IPv6 is the host address assignment and tracking (for logging/auditing reasons), more so if you use SLAAC or (even worse) SLAAC privacy extensions. Not surprisingly, Eric Vyncke and I spent significant time addressing this topic in the IPv6 Security webinar.

I love Greg Ferro’s characterization of CLI:

We need to realise that the CLI is a “power tools” for specialist tradespeople and not a “knife and fork” for everyday use.

However, you do know that most devices’ GUI offers nothing more than what CLI does, don’t you? Where’s the catch?

The current weather around Central Europe doesn’t exactly support this conclusion, but I do get many more “I’m on vacation” responses than usual, so it’s time to reduce the blogging frequency to keep your RSS reader from overloading (you did switch from Google Reader to something like Feedly, didn’t you?).

However, if you’re looking for some really heavy reading, do pick up The Hidden Reality and explore various multiverse proposals. There’s also a beach-friendly version of multiverse discussion: The Long Earth by the one-and-only Terry Pratchett.

During the recent Data Center Fabrics Update webinar Dan Backman from Plexxi explained how their innovative use of CWDM technology and controller-assisted forwarding simplifies deployment and growth of reasonably-sized data center fabrics.

I would highly recommend that you watch the video – the start is a bit short on details, but he does cover all the juicy aspects later on.

NEC and a slew of its partners demonstrated an interesting next step in the SDN saga @ Interop Las Vegas 2013: multi-vendor SDN applications. Load balancing, orchestration and security solutions from A10, Silver Peak, Red Hat and Radware were happily cooperating with ProgrammableFlow controller.

A curious mind obviously wants to know what’s behind the scenes. Masterpieces of engineering? Large integration projects ... or is it just a smart application of API glue? In most cases, it’s the latter. Let’s look at the ProgrammableFlow – Radware integration.

Andreas was watching my recent Enterasys DCI webinar and got intrigued by the quick hand drawings I made, so he asked me “What kind of tool do you use to make the hand drawings during your presentations? It must be something different than a mouse.”

In case you weren’t watching one of my recent webinars, here’s a sample to get you started:

Greg Ferro published a great blog post explaining why he decided to use node.js to build his cloud automation platform. While I agree with most things he wrote, this one prickled me the wrong way:

In my view, an Application Programmable Interface(API) is the fundamental change that makes Software Defined Networking (SDN) a “thing”. We need to realise that the CLI is a “power tools” for specialist tradespeople and not a “knife and fork” for everyday use.

While I agree with his view on CLI, keep in mind that API is no different.

The next small step in my MPLS/VPN update project: EIBGP load balancing – why is it useful, how it works, why can’t you use it without full-blown MPLS/VPN, and what the alternatives are.

Andrew is struggling with MPLS/VPN providers and sent me the following question:

Is "carriers carrier" a real service? I'm having a bit of an issue at the moment with too many MPLS providers […] Carrier’s carrier would be an answer to many of them, but none of the carriers admit to being able to do this, so I was wondering if it's simply that I'm speaking to the wrong people, or whether they really don't...

Short answer: I have yet to see this particular unicorn roaming the meadows of reality.

In the Optimal L3 Forwarding with VARP and Active/Active VRRP blog post I made a remark along the lines of “Things might get nasty [in Arista EOS Virtual ARP world] if you have configuration mismatches”, resulting in a lengthy and amazingly insightful email exchange with Lincoln Dale during which we ventured deeper and deeper down the Virtual ARP (VARP) rabbit hole. Here’s what I learned during out trip: