Blog Posts in March 2019
From CCNA to SDN: Interview with David Bombal
A few weeks ago, I had an interesting video chat with David Bombal in which we covered a wide variety of topics including
- What would you do if you started networking today?
- How do you increase the value of your knowledge?
- Networking hasn’t changed in the last 40 years and whatever you learn about networking will still be valid 20 years from now;
- Why should I learn and implement network automation?
- When should I start learning about network automation?
Note: David posted the whole list of topics with timestamps in the pinned comment under the video.
Automating NSX-T
An attendee of our Building Network Automation Solutions online course decided to automate his NSX-T environment and sent me this question:
I will be working on NSX-T quite a lot these days and I was wondering how could I automate my workflow (lab + production) to produce a certain consistency in my work.
I’ve seen that VMware relies a lot on PowerShell and I’ve haven’t invested a lot in that yet … and I would like to get more skills and become more proficient using Python right now.
Always select the most convenient tool for the job, and regardless of personal preferences PowerShell seems to be the one to use in this case.
Stateful Firewalls: When You Get to a Fork in the Road, Take It
If you’ve been in networking long enough you’d probably noticed an interesting pattern:
- Some topic is hotly debated;
- No agreement is ever reached even though the issue is an important one;
- The debate dies after participants diverge enough to stop caring about the other group.
I was reminded of this pattern when I was explaining the traffic filtering measures available in private and public clouds during the Designing Infrastructure for Private Clouds workshop.
Automation Solution: Create Network Diagram from BGP Data in Nornir
Chris Crook decided to work on a pretty typical problem for his second hands-on assignment in the Building Network Automation Solutions online course: create a network diagram from adjacency data.
He decided to rely on BGP adjacencies (I would usually use LLDP) and added an interesting twist: instead of Ansible he used Nornir with NAPALM.
Must Read: BGP Show and Tell
If you’re a BGP newbie, you’ll love this BGP Show and Tell series from Denise Fishburne. Enjoy!
Multipath TCP on Software Gone Wild
I mentioned Multipath TCP (MP-TCP) numerous times in the past but I never managed to get beyond “this is the thing that might solve some TCP multihoming challenges” We fixed this omission in Episode 100 of Software Gone Wild with Christoph Paasch (software engineer @ Apple) and Mat Martineau from Open Source Technology Center @ Intel.
Creating Automation Source-of-Truth from Device Configurations
Remember the previous blog post in this sequence in which I explained the need for single source-of-truth used in your network automation solution? No? Please read it first ;)
Ready for the next step? Assuming your sole source-of-truth is the actual device configuration, is there a magic mechanism we can use to transform it into something we could use in network automation?
TL&DR: No.
Lock-In and SD-WAN: a Match Made in Heaven
This blog post was initially sent to subscribers of my SDN and Network Automation mailing list. Subscribe here.
I made a statement along these lines in an SD-WAN blog post and related email sent to our SDN and Network Automation mailing list:
The architecture of most SD-WAN products is thus much cleaner and easier to configure than traditional hybrid networks. However, do keep in mind that most of them use proprietary protocols, resulting in a perfect lock-in.
While reading that one of my readers sent me a nice email with an interesting question:
Automating Cisco ACI Environment with Python and Ansible
This is a guest blog post by Dave Crown, Lead Data Center Engineer at the State of Delaware. He can be found automating things when he's not in meetings or fighting technical debt.
Over the course of the last year or so, I’ve been working on building a solution to deploy and manage Cisco’s ACI using Ansible and Git, with Python to spackle in cracks. The goal I started with was to take the plain-text description of our network from a Git server, pull in any requirements, and use the solution to configure the fabric, and lastly, update our IPAM, Netbox. All this without using the GUI or CLI to make changes. Most importantly, I want to run it with a simple invocation so that others can run it and it could be moved into Ansible Tower when ready.
Last Week on ipSpace.net (2019W11)
TL&DR: We ran two workshops in Zurich last week – a quick peek into using Ansible for network automation and updated Building Private Cloud Infrastructure. You can access workshop materials with any paid ipSpace.net subscription.
Now for the fun part…
Feedback: Data Center Interconnects Webinar
I got great feedback about the first part of Data Center Interconnects webinar from one of ipSpace.net subscribers:
I had no specific expectation when I started watching the material and I must have watched it 6 times by now.
Your webinar covered just the right level of detail to educate myself or refresh my knowledge on the technologies and relevant options for today’s market choices
Using Screen Scraping in Network Automation
The first time I encountered screen scraping was in mid-1990. All business applications were running on IBM mainframes those days, and IBM used proprietary terminal system (remember 3270) that was almost impossible to interact with, so some people got the “bright” idea of emulating that screen, scraping information off the emulated screen and copying it into HTML pages… thus webifying their ancient apps.
Networking Events in Europe
A European networking engineer sent me this question:
I'd like to know where other fellow engineers meet up especially in Europe and discuss Enterprise datacenter and regular networking. There are the Cisco Live stuff things to go to but are there any vendor neutral meetups?
Gabi Gerber is organizing networking-focused workshops in Switzerland every quarter (search under SIGS Workshops), and you’re most welcome to join us ;) It’s always a boutique event, but that gives us the ability to chat long into the evening.
Use Network Automation to Detect Software Bugs
This blog post was initially sent to subscribers of my SDN and Network Automation mailing list. Subscribe here.
Here’s a question I got from one of the attendees of my network automation online course:
We had a situation where HSRP was configured on two devices and then a second change was made to use a different group ID. The HRSP mac address got "corrupted" into one of devices and according to the vendor FIB was in an inconsistent state. I know this may be vendor specific but was wondering if there is any toolkit available with validation procedures to check if FIB is consistent after implementing L3 changes.
The problem is so specific (after all, he’s fighting a specific bug) that I wouldn’t expect to find a generic tool out there that would solve it.
Last Week on ipSpace.net (2019W10)
The Spring 2019 Building Network Automation Solutions course continued with an awesome presentation by David Gee. He started with what you should do before writing a single line of code (identify processes and document them in workflows and sequence diagrams) and covered tons of boring stuff nobody ever wants to talk about.
Sample Solution: Automated Auditing Toolbox
Wherever you look you find three kinds of people: those that build tools they need, those that find the tools they need, and those that yammer about the lack of tools without ever doing anything to solve the problem.
Daniel Teycheney is clearly in the first category. When faced with “collect some data and create a simple report” hands-on assignment during the Building Network Automation Solutions course he started creating a toolbox of playbooks that can be used in initial network auditing. I’m positive you’ll find tons of useful tidbits in his code ;)
Building Network Automation Source-of-Truth (Part 2)
In the first blog post of this series I described how you could start building the prerequisite for any network automation solution: the device inventory.
Having done that, you should know what is in your network, but you still don’t know how your network is supposed to work and what services it is supposed to provide. Welcome to the morass known as building your source-of-truth.
Anyone Using Intel Omni-Path?
One of my subscribers sent me this question after watching the latest batch of Data Center Fabrics videos:
You haven’t mentioned Intel's Omni-Path at all. Should I be surprised?
While Omni-Path looks like a cool technology (at least at the whitepaper level), nobody ever mentioned it (or Intel) in any data center switching discussion I was involved in.
Automating Brownfield Device Configuration (Part 2)
A month ago Josef Fuchs described the process he uses to merge existing Cisco IOS device configuration with configuration snippets generated by his network automation solution.
In the second part of his article he dived deep into implementation details, described Ansible playbook and Jinja2 templates he’s using, how he optimized the solution with a custom Jinja2 filter, and the caveats he encountered.
Upcoming ipSpace.net Events and Webinars (March 2019)
We’re starting the Spring 2019 workshop season in March with open-enrollment workshops in Zurich (Switzerland). It was always hard to decide which workshop to do (there are so many interesting topics), so we’ll do two of them in the same week:
- Network and Security Automation with Ansible on March 12th and
- Designing Infrastructure for Private Clouds on March 13th.
Rachel Traylor will continue her Graph Theory webinar on March 7th with a topic most relevant to networking engineers: trees, spanning trees and shortest-path trees, and I’ll continue with two topics I started earlier this year:
Smart NICs and Related Linux Kernel Infrastructure
A while ago we did a podcast with Luke Gorrie in which he explained why he’d love to have simple, dumb, and easy-to-work-with Ethernet NICs. What about the other side of the coin – smart NICs with their own CPU, RAM and operating system? Do they make sense, when and why would you use them, and how would you integrate them with Linux kernel?
We discussed these challenges with Or Gerlitz (Mellanox), Andy Gospodarek (Broadcom) and Jiri Pirko (Mellanox) in Episode 99 of Software Gone Wild.