Do you want to know more about Cumulus Linux after learning what data center architectures it supports, what base technologies it uses, and how you can use it to simplify network configurations? It’s time to explore Cumulus Linux architecture (part 5 of the presentation Dinesh Dutt had during the Data Center Fabrics webinar).

One of the engineers listening to my DMVPN webinars sent me a follow-up question (yes, I always try to reply to them) asking how to implement direct Internet access from the spoke sites (aka local exit) in combination with split default routing you have to use in DMVPN Phase 2 or Phase 3 networks.

It’s really simple: either you have a design requirement that requires split default routing, or you don’t.

One of my readers read the Ars Technica article on ads communicating with other devices via ultrasound and wondered whether something similar could be done for IP.

Not surprisingly, someone already did it. A quick google search found this tutorial which explains how to run IP stack over Gnuradio (at speeds that were last experienced with dial-up modems 30 years ago).

I was asked to present a data-center-related talk last week and decided to focus on one of my favorite topics: because most people don’t have more than a few hundred servers in their data center, they don’t need more than two switches (or a rack of servers).

Not surprisingly, an equipment reseller sitting in the room was not amused.

The video and the slide deck are already online, but there’s a minor challenge: the whole event was in Slovenian ;) However, I plan to record the same topic in English once my SDN travels stop.

I was really excited when Juniper announced Junos Fusion. I hoped for QFabric Done Right, but after watching the NFD10 video describing the architecture, I was disappointed: they reinvented Fabric Extenders.

The blog post was slightly updated on November 14th 2015 based on feedback received from Juniper engineers.

Imagine you’d design your network by documenting the desired traffic flow across the network under all failure conditions, and only then do a low-level design, create configurations, and deploy the network… while being able to use the desired traffic flows as a testing tool to verify that the network still behaves as expected, both in a test lab as well as in the live network.

You might remember all the fuss about various encapsulations used in overlay virtual networking… just because one wouldn’t be good enough (according to Andrew Lerner “we provide users with choice” actually means “we can’t decide which product to offer you”).

Andrew Lerner, my favorite Gartner analyst, recently published a hilarious blog post describing what vendors mean when they say “our product is software-defined” or “we’ll make it work”. Enjoy!

Need more vendorspeak? Try eight levels of vendor acceptance (carefully documented during a particularly stressful on-site test in Poland).

A newbie exploring the mythical lands of SDN might decide to start at the ONF definition of SDN, which currently (November 2015) starts with a battle cry:

The physical separation of the network control plane from the forwarding plane, and where a control plane controls several devices.

The rest of that same page is what I’d call the marketing definition of SDN: directly programmable, agile, centrally managed, programmatically configured, open standards based and vendor-neutral.

One of the typical questions I get in my SDN workshops is “how do you run control-plane protocols like LACP or OSPF in OpenFlow networks?”.

I wrote a blog post describing the process two years ago and we discussed the details of this challenge in the OpenFlow Deep Dive webinar. That part of the webinar is now available with Free ipSpace.net Subscription.