Remember the “BGP as High Availability Protocol” article Nicola Modena wrote a few months ago? He finally found time to extend it with BGP design considerations and a description of a seamless-and-safe firewall software upgrade procedure.

Every now and then a smart person decides to walk away from their competence zone, and start spreading pointless clickbait opinions like BGP is a hot mess.

Like any other technology, BGP is just a tool with its advantages and limitations. And like any other tool, BGP can be used sloppily… and that’s what’s causing the various problems and shenanigans everyone is talking about.

Just in case you might be interested in facts instead of easy-to-digest fiction:

I’ve seen successful public (infrastructure) cloud deployments… but also spectacular failures. The difference between the two usually comes down to whether the team deploying into a public cloud environment realizes they’re dealing with an unfamiliar environment and acts accordingly.

Please note that I’m not talking about organizations migrating their email to Office 365. While that counts as public cloud deployment when an industry analyst tries to paint a rosy picture of public cloud acceptance, I’m more interested in organizations using compute, storage, security and networking public cloud infrastructure.

One of my readers sent me a question along these lines…

VXLAN Network Identifier is 24 bit long, giving 16 us million separate segments. However, we have to map VNI into VLANs on most switches. How can we scale up to 16 million segments when we have run out of VLAN IDs? Can we create a separate VTEP on the same switch?

VXLAN is just an encapsulation format and does not imply any particular switch architecture. What really matters in this particular case is the implementation of the MAC forwarding table in switching ASIC.

After publishing the Disaster Recovery Faking, Take Two blog post (you might want to read that one before proceeding) I was severely reprimanded by several people with ties to virtualization vendors for blaming virtualization consultants when it was obvious the firewall clusters stretched across two data centers caused the total data center meltdown.

Let’s chase that elephant out of the room first. When you drive too fast on an icy road and crash into a tree who do you blame?

• The person who told you it’s perfectly OK to do so;
• The tire manufacturer who advertised how safe their tires were?
• The tires for failing to ignore the laws of physics;
• Yourself for listening to bad advice

For whatever reason some people love to blame the tires ;)

Last Thursday morning I found this gem in my Twitter feed (courtesy of Stefan de Kooter)

Greg Cusanza in #BRK3192 just announced #Azure Extended Network, for stretching Layer 2 subnets into Azure!

As I know a little bit about how networking works within Azure, and I’ve seen something very similar a few times in the past, I was able to figure out what’s really going on behind the scenes in a few seconds… and got reminded of an old Russian joke I found somewhere on Quora:

The previous videos from the How Networks Really Work webinar covered an overview of networking challenges and the importance of networking layers.

Now it’s time to put it all together.

A few days ago we published the content outline for our Networking in Public Clouds online course.

We’ll start with the basics, explore the ways to automate cloud deployments (after all, you wouldn’t want to repeat the past mistakes and configure everything with a GUI, would you?), touch on compute and storage infrastructure, and the focus on the networking aspects of public cloud deployments including:

A Network Artist left a lengthy comment on my Brief History of VMware NSX blog post. He raised a number of interesting topics, so I decided to write my replies as a separate blog post.

Using Geneve is an interesting choice to be made and while the approach has it’s own Pros and Cons, I would like to stick to VXLAN if I were to recommend to someone for few good reasons.

The main reason I see for NSX-T using Geneve instead of VXLAN is the need for additional header fields to carry metadata around, and to implement Network Services Header (NSH) for east-west service insertion.

Imagine you want to create a Jinja2 report that includes only a select subset of elements of a data structure… and want to have header, footer, and element count in that report.

Traditionally we’d solve that challenge with an extra variable, but as Jinja2 variables don’t survive loop termination, the code to do that in Jinja2 gets exceedingly convoluted.

Fortunately, Jinja2 provides a better way: using a conditional expression to select the elements you want to iterate over.