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Category Archives for "ipSpace.net"

Interesting: Hugo with Docsy and AWS Amplify

Mat Jovanovic decided to follow my lead and migrate his blog from Blogger to Hugo, using Docsy theme, AWS Amplify as the CI/CD pipeline, and AWS S3 as the hosting platform.

Nice job… but he did way more than that - he documented the whole process, including tool selection, setup, and Blogger migration.

Thank you Mat! Every time I see someone publishing blog posts about open-source tools on Medium I’ll send them a link to your blog (with a comment “this is how you should blog about open-source solutions").

Video: Internet Has More than One Administrator

It’s amazing how many people assume that The Internet is a thing, whereas in reality it’s a mishmash of interconnected independent operators running mostly on goodwill, misplaced trust in other people’s competence, and (sometimes) pure dumb luck.

I described a few consequences of this sad reality in the Internet Has More than One Administrator video (part of How Networks Really Work webinar), and Nick Buraglio and Elisa Jasinska provided even more details in their Surviving the Internet Default-Free Zone webinar.

You need Free ipSpace.net Subscription to watch the video, and the Standard ipSpace.net Subscription to watch the Surviving in the Internet Default-Free Zone webinar.

Example: Deploy a Web Server in AWS

The third hands-on exercise in our Networking in Public Cloud Deployments online course asks the students to deploy a web server in a public cloud of their choice using infrastructure-as-code principles.

Not surprisingly, Erik Auerswald created another fantastic writeup when solving that exercise, including exploring the problem space, detailed description of his Terraform-based solution, and testing procedures. Enjoy!

AWS Networking 101

There was an obvious invisible elephant in the virtual Cloud Field Day 7 (CFD7v) event I attended in late April 2020. Most everyone was talking about AWS, how their stuff runs on AWS, how it integrates with AWS, or how it will help others leapfrog AWS (yeah, sure…).

Although you REALLY SHOULD watch my AWS Networking webinar (or something equivalent) to understand what problems vendors like VMWare or Pensando are facing or solving, I’m pretty sure a lot of people think they can get away with CliffsNotes version of it, so here they are ;)

Explore: BGP in Data Center Fabrics

Got mentioned in this tweet a while ago:

Watching @ApstraInc youtube stream regarding BGP in the DC with @doyleassoc and @jtantsura.Maybe BGP is getting bigger and bigger traction from big enterprise data centers but I still see an IGP being used frequently. I am eager to have @ioshints opinion on that hot subject.

Maybe I’ve missed some breaking news, but assuming I haven’t my opinion on that subject hasn’t changed.

When EVPN EBGP Session between Loopbacks Makes Sense

One of the attendees of our Building Next-Generation Data Center online course submitted a picture-perfect solution to scalable layer-2 fabric design challenge:

  • VXLAN/EVPN based data center fabric;
  • IGP within the fabric;
  • EBGP with the WAN edge routers because they’re run by a totally different team and they want to have a policy enforcement point between the two;
  • EVPN over IBGP within the fabric;
  • EVPN over EBGP between the fabric and WAN edge routers.

The only seemingly weird decision he made: he decided to run the EVPN EBGP session between loopback interfaces of core switches (used as BGP route reflectors) and WAN edge routers.

Webinars in May 2020

Being stuck at home like most everyone else we’re continuing the increased pace of content production in May 2020:

  • I’ll continue the Introduction to Containers and Docker update. We got through the basics the last time and will cover Linux namespaces and how Docker uses them on May 5th.
  • We finally found an independent guest speaker familiar with Cisco ACI. Mario Rosi will start the Cisco ACI series with an introductory webinar on May 12th.
  • Dinesh Dutt will continue his Network Automation Tools update on May 19th.
  • Hoping to get through Introduction to Docker on May 5th, I plan to do a deep dive into Docker Networking on May 26.
  • Finally, I’m positive I won’t cover all the bridging and routing material I created in today’s webinar, so we’ll continue with routing protocol basics on May 28th.

Network Automation and Hammer of Thor

Imagine that you just stumbled upon the hammer Thor carelessly dropped, and you’re so proud of your new tool that everything looks like a nail even though it might be a lightbulb or an orange.

That happens to some people when they get the network automation epiphany: all of a sudden CLI and manual configuration should be banned, and everything can be solved by proper incantation of Git and Ansible commands or whatever other workflow you might have set up… even though the particular problem might have nothing to do with what you have just automated.

I’m not saying we should keep using box-by-box CLI for daily operations or mundane configuration tasks. I’m just saying that the world is not as binary as some people want it to be.

MUST READ: When Programming a System with High Kinetic Energy

Kode Vicious (aka George V. Neville-Neil ) wrote another brilliant article on reducing risk in systems that can do serious harm. Here are just two of the gems:

The risks involved in these systems come from three major areas: marketing, accounting, and management.

There is a wealth of literature on safety-critical systems, much of which points in the same direction: toward simplicity. With increasing complexity comes increasing risk …

For whatever reason most networking- and virtualization vendors joined a lemming-like run in the opposite direction years ago.

Overlay Networking with Ouroboros on Software Gone Wild

This podcast introduction was written by Nick Buraglio, the host of today’s podcast.


As private overlays are becoming more and more prevalent and as SD-WAN systems and technologies advance, it remains critical that we continue to investigate how we think about internetworking. Even with platforms such as Slack Nebula, Zerotier, or the wireguard based TailScale becoming a mainstream staple of many businesses, the question of “what is next” is being asked by an ambitious group of researchers.

Can We Trust Server DSCP Marking?

A reader of my blog sent me this question:

Do you think we can trust DSCP marking on servers (whether on DC or elsewhere - Windows or Linux )?

As they say “not as far as you can throw them”.

Does that mean that the network should do application recognition and marking on the ingress network node? Absolutely not, although the switch- and router vendors adore the idea of solving all problems on their boxes.

Can We Trust BGP Next Hops (Part 2)?

Two weeks ago I started with a seemingly simple question:

If a BGP speaker R is advertising a prefix A with next hop N, how does the network know that N is actually alive and can be used to reach A?

… and answered it for the case of directly-connected BGP neighbors (TL&DR: Hope for the best).

Jeff Tantsura provided an EVPN perspective, starting with “the common non-arguable logic is reachability != functionality".

Now let’s see what happens when we add route reflectors to the mix. Here’s a simple scenario:

March 2020 on ipSpace.net

We started March 2020 with the second part of Cisco SD-WAN webinar by David Peñaloza Seijas, continued with Upcoming Internet Challenges update, and concluded with 400 GE presentation by Lukas Krattiger and Mark Nowell.

You can access all these webinars with Standard or Expert ipSpace.net subscription. The Cisco SD-WAN presentation is already available with free ipSpace.net subscription, which will also include the edited 400 GE videos once we get them back from our video editor.