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Updated: What is Cumulus Linux All About

Pete Lumbis started his Cumulus Linux 4.0 update with an overview of differences between Cumulus Linux on hardware switches and Cumulus VX, and continued with an in-depth list of ASIC families supported by Cumulus Linux.

You can watch his presentation, as well as the more in-depth overview of Cumulus Linux concepts by Dinesh Dutt, in the recently-updated What Is Cumulus Linux All About video.

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Why Would You Need VXLAN Transport?

It’s amazing how sometimes people fond of sharing their opinions and buzzwords on various social media can’t answer simple questions. Today’s blog post is based on a true story… a “senior network architect” fully engaged in a recent hype cycle couldn’t answer a simple question:

Why exactly would you need VXLAN and EVPN?

We could spend a day (or a week) discussing the nuances of that simple question, but all I have at the moment is a single web page, so here we go…

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Webinars in June 2020

Here’s the final push before we hit the summer break at the end of June (and recover a bit from the relentless production of new content we had throughout the first half of 2020):

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BGP AS Numbers on MLAG Members

I got this question about the use of AS numbers on data center leaf switches participating in an MLAG cluster:

In the Leaf-and-Spine Fabric Architectures you made the recommendation to have the same AS number on all members of an MLAG cluster and run iBGP between them. In the Autonomous Systems and AS Numbers article you discuss the option of having different AS number per leaf. Which one should I use… and do I still need the EBGP peering between the leaf pair?

As always, there’s a bit of a gap between theory and practice ;), but let’s start with a leaf-and-spine fabric diagram illustrating both concepts:

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Feedback: Data Center for Networking Engineers

When I started designing Data Center Infrastructure for Networking Engineers webinar I wanted to create something that would allow someone fluent in networking but not in adjacent fields like servers or storage to grasp the fundamentals of data center technologies, from server virtualization and containers to data center fabrics and storage protocols.

Here’s what a network architect said about the webinar:

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Musings on IP Packet Reordering

During the Comparing Transparent Bridging and IP Routing part of How Networks Really Work webinar I said something along the lines of:

While packets should never be reordered in transit in transparent bridging, there’s no such guarantee in IP networks, and IP applications should tolerate out-of-order packets.

One of my regular readers who designs and builds networks supporting VoIP applications disagreed with that citing numerous real-life examples.

Of course he was right, but let’s get the facts straight first:

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Intent-Based Networking: Another Victim of Sturgeon's Law

A few days ago Greg Ferro published an interesting post claiming DHCP is an example of intent-based networking (a bit less tongue-in-cheek than my “so is OSPF configuration” rant from 2017). BTW, so is RADIUS or TACACS+ ;)

He got quickly “corrected” by Phil Gervasi who loosely relied on Gartner’s definition of Intent-Based Networking, and claimed that an intent-based networking system should have three major components:

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Smart NICs with Silvano Gai on Software Gone Wild

A while ago we discussed a software-focused view of Network Interface Cards (NICs) with Luke Gorrie, and a hardware-focused view of them with Or Gerlitz (Mellanox), Andy Gospodarek (Broadcom) and Jiri Pirko (Mellanox).

Why would anyone want to implement features in hardware and not in software, and what would be the best hardware implementation? We discussed these dilemmas with Silvano Gai in Episode 110 of Software Gone Wild podcast.

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Feedback from Another SD-WAN Fan

I don’t know what’s wrong with me, but I rarely get emails along the lines of “I deployed SD-WAN and it was the best thing we did in the last decade” (trust me, I would publish those if they’d come from a semi-trusted source).

What I usually get are sad experiences from people being exposed to vendor brainwashing or deployments that failed to meet expectations (but according to Systems Engineering Director working for an aggressive SD-WAN vendor that’s just because they didn’t do their research, and thus did everything wrong).

Here’s another story coming from Adrian Giacometti.

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Do We Need Bare Metal Servers in Public and Private Clouds?

Whenever I was comparing VMware NSX and Cisco ACI a few years ago (in late 2010s in case you’re reading this in a far-away future), someone would inevitably ask “and how would you connect a bare metal server to a VMware NSX environment?

While NSX-T has that capability since release 2.5 (more about that in a later blog post), let’s start with the big question: why would you need to?

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