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Blog Posts in January 2017

Why Are High-Speed Links Better than Port Channels or ECMP

I’m positive I’ve answered this question a dozen times in various blog posts and webinars, but it keeps coming back:

You always mention that high speed links are always better than parallel low speed links, for example 2 x 40GE is better than 8 x 10GE. What is the rationale behind this?

Here’s the N+1-th answer (hoping I’m being consistent):

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To Drop or To Delay, That’s the Question on Software Gone Wild

A while ago I decided it's time to figure out whether it's better to drop or to delay TCP packets, and quickly figured out you get 12 opinions (usually with no real arguments supporting them) if you ask 10 people. Fortunately, I know someone who deals with TCP performance for living, and Juho Snellman was kind enough to agree to record another podcast.

Update 2017-03-31: Added More information section

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Using Ansible Networking Modules

One of the engineers attending my Building Network Automation Solutions online course got the lab up and running, wanted to execute a simple IOS command from an Ansible playbook and failed.

He quickly realized he needs to set connection to local or network_cli; for more details watch the Connecting and Authenticating section of Ansible Networking Modules - Executing Commands part of Ansible for Networking Engineers webinar.

New Webinar: PowerShell for Networking Engineers

Ansible (or Python+Paramiko/Netmiko) seems to be the tool used in most do-it-yourself network automation presentations and videos. Did you know there’s a scripting/automation alternative that’s hugely popular in parts of sysadmin and virtualization universe that almost nobody talks about in networking (because everyone is focused on huge data center fabrics and unicorns) – PowerShell (now also available on OSX and Linux).

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New Webinar: Automating Data Center Fabric Deployments

The next session of the Network Automation Use Cases series will take place on January 24th. Dinesh Dutt will explain describe how you can use Ansible and Jinja2 to automate data center fabric deployments, and I’ll have a few things to say about automating network security.

If you think that what Dinesh will talk about applies only to startups you’re totally wrong. UBS is using the exact same approach to roll out their new data centers; Thomas Wacker will share the details in his guest presentation in the next Building Next-Generation Data Centers online course.

VXLAN Ping and Traceroute

From the moment Cisco and VMware announced VXLAN some networking engineers complained that they'd lose visibility into the end-to-end path. It took a long while, but finally the troubleshooting tools started appearing in VXLAN environment: NVO3 working group defined Fault Managemnet framework for overlay networks and Cisco implemented at least parts of it in recent Nexus OS releases.

You'll find more details in Software Gone Wild Episode 69 recorded with Lukas Krattiger in November 2016 (you can also watch VXLAN Technical Deep Dive webinar to learn more about VXLAN).

Introduction to Docker: Featured Video of January 2017

The featured webinar in January 2017 is the Introduction to Docker webinar, and in the featured video Matt Oswalt explains the basic Docker tasks. Other videos in this webinar cover Docker images, volumes, networking, and Docker Compose and Swarm.

To view the featured video, log into my.ipspace.net, select the webinar from the first page, and watch the video marked with star.

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Device Configurations Are Not a Good Source of Truth

One of my subscribers sent me this question after watching the second part of Network Automation Tools webinar (or maybe it was Elisa Jasinska's presentation in the Data Center course):

Elisa mentions that for a given piece of data, there should be “one source of truth”. It gets a bit muddled when you have an IPAM tool and Git source control simultaneously. It is not hard to imagine scenarios where these get out of sync especially if you consider multi-operator scenarios.

Confused? He provided a simple scenario:

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