Cisco SDA case study #1 – the case of the traffic that won’t get denied
In this post, we will look at a peculiar case of a SGACL not denying traffic between two hosts in a SD-Access fabric.
In this post, we will look at a peculiar case of a SGACL not denying traffic between two hosts in a SD-Access fabric.
I am by no means a developer (not by a long shot!), but I have been learning lots of development-related things over the last several years and trying to incorporate those into my workflows. One of these is the idea of test-driven development (see Wikipedia for a definition and some additional information), in which one writes tests to validate functionality before writing the code to implement said functionality (pardon the paraphrasing). In this post, I’ll discuss how to use conftest
to (loosely) implement test-driven development for Kustomize overlays.
If you’re unfamiliar with Kustomize, then this introductory article I wrote will probably be useful.
For the discussion around using the principles of test-driven development for Kustomize overlays, I’ll pull in a recent post I did on creating reusable YAML for installing Kuma. In that post, I pointed out four changes that needed to be made to the output of kumactl install control-plane
to make it reusable:
caBundle
value for all webhooks.caBundle
value.Remember the unnumbered IP interfaces saga? Let’s conclude with the final challenge: can we run link-state routing protocols (OSPF or IS-IS) over unnumbered interfaces?
Quick answer: Sure, just use IPv6.
Cheater! IPv6 doesn’t count. There are no unnumbered interfaces in IPv6 – every interface has at least a link-local address (LLA). Even more, routing protocols are designed to run over LLA addresses, including some EBGP implementations, allowing you to build an LLA-only network (see RFC 7404 for details).
OK, what about IPv4?
TL&DR: It works, but…
Remember the unnumbered IP interfaces saga? Let’s conclude it with the final challenge: can we run link-state routing protocols (OSPF or IS-IS) over unnumbered interfaces?
Quick answer: Sure, just use IPv6.
Cheater! IPv6 doesn’t count. There are no unnumbered interfaces in IPv6 – every interface has at least a link-local address (LLA). Even more, routing protocols are designed to run over LLA addresses, including some EBGP implementations, allowing you to build an LLA-only network (see RFC 7404 for details).
OK, what about IPv4?
TL&DR: It works, but…
2022 Goals In 2021, the pandemic managed to get to me. It seemed like alot of curve balls came my way. But, myself and my family came out the other end healthy and in relatively good spirits. 2022 is going to be a bit of a do-over in terms of my goals for the year. Without further...continue reading
As part of a POC I deployed a pair of HA F5 LTM/GTM at home to use for all things DNS based. It is an indulgent over the top DNS solution for a 1 bed flat, but hey-ho we are in a pandemic….. This guide does not go through the HA F5 or GTM (still cant stop calling it that) configuration, it is focussed around using ZoneRunner for DNS (bind) with these zones transferred into DNS express and serviced by a listener.
A friend of mine recently had a solar panel system installed on his acreage. Besides being interesting because of the renewable/green aspect of the project, the system itself—from SolarEdge—is actually highly digital.
The last point interested me the most because any time a device exposes its data or a control connection, it means there’s an opportunity to integrate it with other software. In this case, I wanted to create my own dashboard to display (near) real-time performance data for the system.
Whereas other blogs and articles on this topic describe how to monitor a single inverter system, this post will describe how I built a performance dashboard for a multi-inverter system.
This post originally appeared on the Packet Pushers’ Ignition site on August 20, 2021. For both individuals and businesses, the past 18-months have vastly increased their reliance on the Internet to access cloud services, online retail and entertainment venues and each other via high-definition video conferences. In the period from just before the initial SARS-CoV-2 […]
The post Carriers Are Scaling Backbones With Merchant Silicon & Disaggregated, Distributed Networking appeared first on Packet Pushers.
Previous Post – https://r2079.wordpress.com/2021/12/28/enhanced-networking-1-sriov-aws/
As Discussed in Part-1 SRIOV (Enhanced Networking on EC2) can be enabled in two ways, the first in the series is by far the simplest one, Enabling it with using ENA (Elastic Network Adapter).
Great, would that work for any instance – The answer is NO!, below are the specifications, to make summarize any Instance other than C4, D2, M4 instances smaller than m4.16xlarge, or T2 from current generation Instances.
https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/enhanced-networking-ena.html
How do I Check:
The Latest Ubuntu / Amazon Linux AMI include the module required for Enhanced networking with ENA installed and enabled for support, if you happen to use the old AMI’s the procedure listed in the above webpage will help
Testing:
I spin up a T3.large instance and below is how it looks like
You also have the option to verify it in a Cloud shell
How do you know if AMI supports it?
Finally on the interface itself
The next post will be similar but would cover an Intel specific Network Adapter.
-Rakesh
I’m positive that this pointer to The Gift of It’s Your Problem Now by Avery Pennarun will generate similar comments to the blockchain one: “he’s an idiot, and you’re an idiot for wasting my time posting this”.
That might be true, but in that case he’s my kind of idiot, and you shouldn’t complain about a gift anyway – there are tons of high-quality lolcats videos waiting for you instead.
I’m positive that this pointer to The Gift of It’s Your Problem Now by Avery Pennarun will generate similar comments to the blockchain one: “he’s an idiot, and you’re an idiot for wasting my time posting this”.
That might be true, but in that case he’s my kind of idiot, and you shouldn’t complain about a gift anyway – there are tons of high-quality lolcats videos waiting for you instead.
When my eldest son was just a baby, he had toys that looked like little baseballs. Long story short, I decided to teach myself to juggle with them. I’d always wanted to learn and thought to myself “How hard can it be?” Well, the answer was harder than I thought and it took me more time that I realized to finally get the hang of it.
One of the things that I needed to learn is that adding in one more ball to track while I’m trying to manage the ones that I had wasn’t as simple as it sounded. You would think that adding in a fourth ball should only be about 25% harder than the three you had been working with before. Or, you might even believe the statistical fallacy that you’re only going to fail about a quarter of the time and be successful the rest. The truth is that adding in one more object makes your entire performance subpar until you learn to adjust for it.
I mention this example because the most obvious application for the juggling metaphor is in Quality of Service (QoS). If you’ve ever read any of Continue reading