Jerome Tissieres

Author Archives: Jerome Tissieres

Cisco Live 2022

Cisco Live US 2022 will be June 12-16 in Las Vegas. After two years of virtual conferences and being vaccinated three times against Covid-19, I’m more than motivated to go in person! However, for those who are still hesitating, there is also an online version, over two days, probably in a similar format to 2021. I am really looking forward to it and being able to talk and interact with my former colleagues, friends, and peers again. This is probably the best part about attending a conference in person: meeting…

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Cisco DCAUTO exam study resources

I just passed the Cisco DevNet DCAUTO (300-635) exam (Yay!). This is my 3rd Cisco exam on network automation after NPDESI in 2018 (replaced now by the DevNet program), and DevNet CORE (DEVCOR) in 2020. But this time, I documented everything I read, so I could report it here and build a Cisco DCAUTO exam study resources. By doing this, I hope to help anyone who wants to study for this certification. And, as I have already passed the DevNet CORE exam, I am now Cisco certified DevNet Professional.  …

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2021 IT Blog Awards finalist!

IT Blog Awards Finalist 2021

I have the honor of having my blog selected as a finalist in the 2021 IT Blog Awards, hosted by Cisco. It is a privilege and a great joy for me to have my blog selected for the fourth consecutive year! Congratulations also to all of the other finalists, who all produce great and valuable content! Click here to vote and choose the winner of the 2021 IT Blog Awards. If you want to vote for my blog, you can find it under: “Let’s talk about Network“, thank you in advance…

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First steps with pyATS

pyATS

Have you ever wanted to compare the operational state of a bunch of network devices between two specific times? Not only if the interfaces are up or down, but the number and status of BGP peers, the number of prefixes received, the number of entries into a MAC-address table, etc? This is something quite laborious to do with classical NMS or Do-It-Yourself scripts. And this is where pyATS can become a real asset. Here are my first steps with pyATS: Network Test & Automation Solution. What is pyATS? pyATS (pronounced…

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How to simulate a host in a real network?

How to simulate a host

Like some other posts, I didn’t think I would write this one because it seemed obvious. But, after talking to a lot of engineers and customers, I realized that not everyone knows this trick. So here it is. The question is this: how to simulate a real host in a physical network environment when you don’t have computer at your disposal? Well, let’s take an example. The environment Here is an example with a very simple VXLAN topology consisting of two spines and two leafs. I’m using Cisco Nexus switches…

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Basic Linux Networking tips and tricks part-5: tcpdump

tcpdump-logo

Here is another post of the series on basic network troubleshooting and tools under Linux. In this post, I will talk about tcpdump. Other posts of the series This post is part of a series of basic Linux Networking tips and tricks. The other posts of this series are: The ip and nmcli commands The mtr command The ss and netstat commands The curl command tcpdump Introduction I think the most essential element to debug a network problem is a packet capture tool or sniffer, and the most common one…

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25 years as a Network Engineer!

Cisco-2501

In January 1996, I entered for the first time in the configuration of a Cisco 2501 router. This was the beginning of my career as a network engineer. That was just 25 years ago! Here’s a quick look back and a few tips for junior engineers who are at the beginning of their careers.   25 years as a Network Engineer! In 25 years, I had the opportunity to change several times my working environment and specialty as a network engineer: I went from network engineer and peering-manager for regional…

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Goodbye 2020… and never come back!

As we approach the end of the year, we can finally say goodbye to 2020. Goodbye 2020… and never come back! But, it is also time to look back at 2020 and try to see what the year 2021 promises us. So, in 2020…   COVID-19! The first thing that comes to mind when we talk about this year, and I think this will be the case for a long time, is the COVID-19! Who could have foreseen at the beginning of January that the entire world would be masked…

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2020 IT Blog Awards finalist!

2020 IT Blog Awards finalist

I have the honor of having my blog selected as a finalist in the Most Educational category of the 2020 IT Blog Awards, hosted by Cisco. It is an honor and a great joy for me to be selected, for the third consecutive year, alongside other high-level bloggers who all have very deep technical knowledge! I hope you enjoy my articles as much as I enjoy writing and sharing them. I know I could write more, but I try to put quality ahead of quantity.   Please click here to vote…

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How to Overcome the Impostor Syndrome as Network Engineer

imposter-syndrome

Many network engineers, myself included, sometimes feel like they don’t belong and don’t deserve to be here. Here are a few tips to combat the impostor syndrome. Sometimes, do you feel like an impostor? This is quite common in IT: you feel like an impostor. Even when you’ve got THE dream job, or when you’ve earned this recognition, or when you’ve passed that famous certification… You can’t get rid of the feeling that it’s just smoke, that you must have fooled everyone and that at any moment you will be…

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My Cisco DevNet Core Exam Journey

Cisco DevNet Specialist

On 23 October 2020, I took and passed the Cisco Certified DevNet Professional Core exam (350-901 DEVCOR) on my first attempt. I explain here the resources I used to study and pass this exam. My background and experience Before I explain what and how I have studied, you need to understand what I already knew, what was my background and experience with some of the topics of the exam before I started to study for it. At the end of April 2018, I already passed a Cisco specialist certification on…

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OnVue – Get certified from your home

OnVue

One of the positive aspects of this difficult period, if I may say so, is the possibility of taking a Pearson Vue test online, called OnVue. Last Friday, October 23rd, I took a Cisco exam from home and I think it’s interesting to share with you the details of this experience. With OnVue – Get certified from your home! The registration for the exam The registration for the test is almost the same as for a Cisco test done in a Vue test center. Go to the website of Pearson…

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RDMA over Converged Ethernet (RoCE) on Cisco Nexus 9300

RoCE - Rocky

On a previous post, I made an introduction about NVMe, NVMe-oF and RDMA for network engineers. In this post, I’m going to talk about RDMA over Converged Ethernet (RoCE) and more specifically how to implement and configure the QoS part of RoCEv2 on the Cisco Nexus 9300 series. What is RoCE? RDMA over Converged Ethernet (RoCE – pronounced “Rocky”) is a network protocol that allows Remote Direct Memory Access (RDMA) over an Ethernet network. It does this by an encapsulation of an InfiniBand transport packet over Ethernet. There are two…

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NVMe, NVMe over Fabrics and RDMA for network engineers

HDD

In the past, the evolution of network-based storage was not really a problem for network engineers: the network was fast and the spinning hard drives were slow. Natural network upgrades to 10Gb, 40Gb, and 100Gb Ethernet were more than sufficient to meet the networking needs of storage systems. But now, with the introduction of ultra-fast solid-state disks (SSDs) and Non-Volatile Memory Express (NVMe), this is no longer true! Storage teams now have the ability to potentially saturate the network with incredibly fast devices. Network-based storage (SANs) using NVMe technology –…

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Basic Linux Networking tips and tricks part-4: curl command

cURL

Here is another post of the series on basic network troubleshooting and tools under Linux. In this post, I will talk about the cURL command.   Others posts of the series This post is part of a series about basic Linux Networking tips and tricks. The others posts of this series are: The ip and nmcli commands The mtr command The ss and netstat commands The curl command   What is cURL? cURL is a Linux command-line tool for getting or sending data and files, using an URL syntax. Since cURL…

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Automate file uploads to your Cisco Nexus switches

If you have more than three Cisco Nexus switches in nx-os mode, and you are not using Cisco DCNM or any other similar tool, you probably already have encountered this question: How to automate file uploads to your Cisco Nexus switches? Here is a turnkey Python script using Netmiko’s SCP function to do this. This script is very simple, it relies only on Netmiko functions and SCP. But it does its job very well and I share it here because it can certainly help you to save time.   What…

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Basic Linux Networking tips and tricks part-3: ss and netstat commands

Here is the third post of the series on basic network troubleshooting and tools under RHEL / CentOS. In this post, I will talk about the netstat and ss commands.   Others posts of the series This post is part of a series about basic Linux Networking tips and tricks. The others posts of this series are: The ip and nmcli commands The mtr command The ss and netstat commands The curl command   netstat The netstat command is a network utility used to display network connections, protocol  or interfaces…

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Cisco Live US 2020: To CLUS or not to CLUS? [updated]

CLUS-2020

Update March 16, 2020: The in-person event is “relaunched” as an online event. Here is a copy of the information email I just received: The health and well-being of our customers, partners, employees and communities is of utmost importance to us. As a result, during this unprecedented time of the COVID-19 pandemic, Cisco Live, our premier in-person customer and partner experience of the year, is being relaunched as a complimentary, full-scale digital event, enabling remote participation from anywhere in the world. We’re dedicated to making sure that the experience at…

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Cisco Certifications changes: a short summary

Unless you’ve been living in a cave during the last nine months, specifically since Cisco Live US 2019, you should know that last Monday, February 24th, was the D-day for big changes in Cisco certifications. Here is a short summary of the major changes and what to remember about them. Changes on current certifications Associate level The various CCNA certifications have been consolidated to only one now. And the CCDA also disappears. Remaining certs at associate level are: CCNA DevNet Associate (I will talk about DevNet certs more in details…

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Cisco NX-OS Graceful Insertion and Removal (GIR)

Cisco GIR

If you operate a data-center network with Cisco Nexus, you’ve probably already faced the problem of how to perform a maintenance on one of the two switches of a vPC pair, with minimum impact and risks for the production network. Cisco NX-OS contains a feature called “Graceful Insertion and Removal” or GIR to help you for that. Here is how it works. Scenario Let’s take the example below: (click on the image to see a larger version) We have two Nexus (in nx-os mode) in vPC. Doing layer-2 aggregation and …

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