I got a long list of VXLAN-related questions from one of my subscribers. It started with an easy one:

Does Cisco ACI use VXLAN inside the fabric or is something else used instead of VXLAN?

ACI uses VXLAN but not in a way that would be (AFAIK) interoperable with any non-Cisco product. While they do use some proprietary tagging bits, the real challenge is the control plane.

One of my readers wondered whether it makes sense to attend my Building Network Automation Solution course even if they plan to deploy a $Vendor platform.

It depends, this time on how fast and how far you want to proceed with network automation.

Another great blog post by Russ White: DNS is part of the TCP/IP stack, get used to it.

You might also want to tell application developers hard-coding IP addresses or anyone else believing in using /etc/hosts files instead of DNS that those things stopped being sexy around 1980.

A while ago I wrote:

I haven’t seen any hard data, but intuition suggests that apart from hardware failures a standalone firewall might be more stable than a state-sharing firewall cluster.

Guillaume Sachot (working for a web hosting company) sent me his first-hand experience on this topic:

During our summer team-building podcast we agreed it would be fun to record a few episodes along the “how do I become a programmer” theme and figured out that Elisa Jasinska would be a perfect first candidate.

A few weeks ago we finally got together and started our chat with campfire stories remembering how we got started with networking and programming.

I got into an interesting discussion with Johannes Luther on the need for VRFs and he wrote:

If VRF = L3 virtualization technologies, then I saw that link. However, VRFs are again just a tiny piece of the whole story.

Of course he’s right, but it turns out that VRFs are the fundamental building block of most L3 virtualization technologies using a shared infrastructure.

One of the challenges traditional networking engineers face when starting their network automation journey is the “build or buy” decision: should I use a plethora of small open-source or commercial tools and components and build my own solution, or should I buy a humongous platform from a reassuringly-expensive $vendor.

Most of us were used to buying platforms ranging from CiscoWorks to HP OpenView (oops, Business Technology Optimization Software) or now Cisco’s NSO, so it’s natural that we’re trying to map this confusing new world into old patterns, leading to interesting discussions like the one I had during one of my workshops:

In June 2016 I got an interesting idea: let’s create a webinar series with numerous guest speakers that would describe several widely-used network automation use cases.

It took me almost half a year to get there, but finally the first session is scheduled for November 22nd.

One of my readers sent me an interesting question a while ago:

Isn’t IS-IS a better fit for building L3-only networks than BGP, particularly considering that IS-IS already has a protocol to communicate with the end systems (ES-IS)?

In theory, he’s correct (see also this blog post).

Our Data Center optimization journey has finished. We virtualized the workload, got rid of legacy technologies, reduced the number of server uplinks, replaced storage arrays with distributed file system and replaced physical firewalls and load balancers with virtual appliances.

Let’s see what’s left: it turns out you really don’t need more than two switches in most data centers.

I encountered an ancient problem during one of my ExpertExpress engagements:

• Customer network is split into two autonomous systems (core and access);
• Links within access network are way slower than links within core network;
• Customer would like to have optimal core-to-access traffic flow.

Challenge: what’s the simplest possible configuration to get it done?

Got this comment on my Network Automation RFP Requirements blog post:

Looks like you are paid shill for Brocade based on the quote earlier in your blog "The Pass/Fail information included below was collected to the best of my knowledge with extensive help from Jason Edelman, Nick Buraglio, David Barroso and several Brocade engineers (THANK YOU!)."

Hooray, one more accolade to add to my list of accomplishments. And now for a few more details:

It’s only two weeks since the last live session of the Autumn 2016 Data Center course in which Mitja Robas did a fantastic job describing a production deployment of VMware NSX on top of Cisco Nexus 9000 network, and we already have the first speakers for the Spring 2017 event:

• Scott Lowe (now at VMware) will talk about the role of open source in data center infrastructure;
• Thomas Wacker (UBS AG) will talk about their fully automated data center deployments;
• Andrew Lerner and Simon Richard (Gartner) will participate in a panel discussion on data center and networking trends.

We did a podcast describing NAPALM, an open-source multi-vendor abstraction library, a while ago, and as the project made significant progress in the meantime, it was time for a short update.

NAPALM started as a library that abstracted the intricacies of network device configuration management. Initially it supported configuration replace and merge; in the meantime, they added support for diffs and rollbacks

One of my readers left this comment (slightly rephrased) on my Network Automation RFP Requirements blog post:

Given that we look up to our *nix pioneers as standard bearers for system automation, why do we demand an API from network devices? The API requirement would make sense if the vendor OS is a closed system. If an open system vendor creates APIs for applications running on their system (say for BGP configs) - kudos to them, but I no longer think that should be mandated.

He’s right - API is not a mandatory prerequisite for reliable network automation.