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VIP Perspectives

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Depending on whether your ISE deployment is small, medium, or large, you might need to add additional nodes with different personas. The persona in ISE cube is just a fancy name to define what services would be running on a node. The main three personas are Administration (PAN), Policy Service (PSN), and Monitoring and Troubleshooting (MnT). The primary/secondary concept exists only with PAN and ... Read more

Smoke and Mirrors: ACI L4-L7 Service Insertion with Policy-Based Redirect...Just for Fun! By Micheline Murphy   Traffic in a data center is a lot like an irrigation system. You need to make sure that there are no dry spots, of course.  But just delivering water might not be enough. Sometimes you might need to make sure that the volume in a channel don't exceed capacity. You might need ... Read more

The purpose of this post about SDN and SD-Access   Last year I made a post about Virtualization and the year before that I wrote about Network Terminology. In those posts I discussed a little bit how important it is to understand what you say and that virtualization literally changed everything. This year I wanted to continue along that journey and introduce you to Cisco’s automation ... Read more

You might have read many times during your studies that changing the native VLAN1 on Cisco switch trunk ports is highly recommended. Some documentations do not give any explanation about this recommendation, others might give a hint associating the recommendation to security, and still others might give a brief explanation referring to preventing VLAN Hopping Attack.   Why VLAN1 in ... Read more


Tools of the New Networking Era

Posted by Sergey Jun 14, 2019

Everyone has noticed the buzz around new trends in networking: automation and programmability.While there is a lot of debate going on about whether the new way will eventually push out old-school engineers or if it will subside eventually, it might be helpful to get familiar with some of the tools that this "brave new world" is bringing upon us. As programmability and automation suggest writing ... Read more

More Shenanigans: vPC, VXLAN and ACI...Just for Fun! by Micheline Murphy In my last installment of "...Just for Fun!" we began our exploration into virtual port channels. First, we looked at a vPC pair in complete isolation, and then some failure scenarios. Let's continue our exciting adventure by exploring vPCs in a VXLAN environment and then round out the day with a peek into vPCs in ACI. ... Read more

We Don't Need No Stinkin' Flags! ACI External EPG Subnet Flags...Just for Fun! by Micheline Murphy   In ACI, the L3Out is a veritable Howl’s Moving Castle[i] of configuration whose ultimate goal is to deliver external connectivity to the endpoints in the ACI fabric. All told, I think there are something in excess of twenty steps to go from zero to full connectivity between an outside ... Read more

Conning the System: Virtual Port Channels...Just for Fun! by Micheline Murphy   Virtual port channels are the tricksters of the networking world. They were originally developed as a con game, way to link two switches together and fool the rest of the network into thinking they were only a single switch. The biggest driver for developing vPC technology was to avoid having spanning-tree come ... Read more

  In the age of digital transformation, it can be challenging to understand educational paths, certification paths, and career paths. For this reason, it is more important than ever for people coming into this industry to have role models and mentors. What is mentoring though? Mentoring to me is not about me holding your hand every step of the way. Mentoring is not me doing your work. ... Read more

David P.

Demystifying CEF

Posted by David P. Mar 28, 2019

It's a common fact that we tend to ignore things that are taken for granted as we assume their presence to be constant over time. This applies undeniably to many aspects of our lives, including work. In this post I intend to describe the history and drivers behind Cisco Express Forwarding (CEF), its inner moving parts, how it carries out its tasks and why we should not take this feature for ... Read more

How's About a Little VXLAN... Just for Fun. by Micheline Murphy   Have you ever trouble-shot a system that wasn’t broke? What? Troubleshooting something that isn’t broken might seem like total madness, but it is a really good way to really become intimately familiar something while it’s actually working.  So, in the spirit of fun and unbridled exploration, ... Read more

Intermediate System to Intermediate System, commonly abbreviated IS-IS, and unfortunately often attributed without the hyphen, began as a research project at Digital Equipment Corporation in 1986 as part of a suite of protocols named DECNET. [1]  It was a full 6 years later that IS-IS was offically recognized as “Intermediate System to Intermediate System intra-domain routeing ... Read more

Application containerization, or lightweight process virtualization, is a method used for deploying multiple isolated applications over a single host accessing the same operating system (OS). By using application containers, you can run many containerized processes or apps on a machine, each process giving the user the illusion that it runs over a dedicated OS. In this blog post, we'll cover ... Read more

The networking industry is currently going through major changes. We are moving–or at least trying to move–from managing devices one by one via CLI to networks where we automate, be it via scripts, automation products, or software-defined solutions. What does this mean for the “modern” network engineer? What are the most important skills to have? How am I supposed to keep ... Read more

Introduction  I remember when I first started working with IT and heard the term “virtual” for the first time. When I tried to understand what it was and how it worked, it was like magic. I couldn’t see it, yet something was working in the background like magic to do good or bad deeds without my knowledge! This was in the era where you physically had to put ... Read more

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