Thoughts on

Infrastructure Firmware Upgrade: Beyond CLI Commands and Change Windows

Wed, 03 Jun 2026 21:31:13 +0200

When a piece of infrastructure needs a firmware upgrade, most engineers and consultants typically think of two things:

the set of CLI commands to enter on each individual device,
the date of the maintenance window. A proper firmware upgrade is much more than that. Here is my framework for infrastructure firmware upgrades, which remains relevant whether we are dealing with CLI-managed devices or software-defined GUI-based controllers. I dissect it into the following phases.

Alignment phase

Define scope of work.
Explain the intended preparatory work and align it with customer expectations.
Define the responsibilities.
Define the nature of the interaction with the customer: preferred and reasonable type of communication (calls, workshops), remote vs onsite, frequency.

Deliverables and Output

Scope of Work
RACI Matrix

Discovery phase

In this phase, the following data must be gathered:

Service Graph Rendering Expectations vs Reality

Sat, 23 May 2026 11:31:13 +0200

Creating a Service Graph Template, applying it and not finding any faults is one thing. Seeing the rendered Service Graph is another thing.

Observation

The rendering of a Service Graph Template is dependent on the following:

existence of two EPGs with a contract relationship,
existence of an association between the contract and the Service Graph
existence of contract-matching traffic, i.e. the existence of traffic that matches that contract. As soon as that contract is attached to the Service Graph Template during the “Apply Service Graph Template” phase, then that is the moment where the Service Graph Instance appears in the APIC GUI.

Critique

When I look for the requirements for deploying Service Graph Redirects in the ACI Service Graph Whitepaper document, the assumption mentioned in the ‘Configuration’ paragraph reads a bit vague: The activation condition of a Service Graph Template remains open and can only be clarified with these questions:

Working as a Network Engineer

Sun, 08 Sep 2013 21:31:13 +0200

When you work in Operations and you tell your internal clients that you work as a network engineer, they often think that you are “Mr All-computer-stuff”. That is often the case regardless of where the client is in the company hierarchy. They expect you to fix any computer issue they have at hand. Onsite interventions feel like you were dropped in a tribal region in a forest while equipped with a Swiss-army knife.

Your Phone Conversation Started Earlier Than You Think

Sun, 08 Sep 2013 21:31:13 +0200

Something that I noticed over the years, after countless phone calls I’ve had with co-workers, managers, service providers and clients, is that people react best to your message if you talk to them as if they were physically in front of you. It’s not because your voice sounds different on the phone that you treat people in a mediocre fashion. It’s not because the other person is far away that you can afford to downsize him or her. I even find myself gesturing like I was giving a speech in front of deaf people! Does that mean that I should pay attention to my facial expressions? To some extent yes. But, the universal emotions of joy, sadness, anger and deception can definitely be wonderfully encoded in your voice while on the phone. That is the reason why the smile of a caring customer service agent can not be mistaken. And that makes the other person comfortable and very receptive to you.

TSHOOT Exam Feedback

Thu, 26 May 2011 21:31:13 +0200

Finally, I passed. I feel so happy that two years of discontinuous study and a lot of frustration paid off. I deserve this nice recognition :) Now, I can tell that it takes a LOT of patience, focus and self confident to pass not only this exam, but the whole track. Why? because many guys fall in the trap of cramming questions in order to become CCNP fast. I began the CCNP journey in 2009. I only became CCNP in 2011! Some guys may tell me that I was not serious about my studies. But here are my arguments:

TSHOO Exam Day is Near

Tue, 24 May 2011 21:31:13 +0200

Two days are left before my TSHOOT exam. I feel confident about it since I have a first taste of it. I read feedback given by test takers that it is a a nice experience. I ought to be ready for both scenarios. If I succeed, then I know that all my limiting beliefs about CCNP were false. Then, I’ll know that I was prisoner of my false beliefs. And if I fail, then I should remind myself about all the courageous people in the IT world who spent a lot of money and time in the pursuit of their certs. Either way, I’ll learn something, and that’s my own choice. I made my choice to enhance my career, no matter what the sacrifices are. “Courage is resistance to fear, mastery of fear - not absence of fear” - Mark Twain