IOS and NX-OS Ping Script using TCL

There are many situations in which you may need to ping a large number of IP addresses. You can use the Tcl (usually pronounced “tickle”) shell built-in in both IOS and NX-OS to accomplish this task.

Simply replace the below IP addresses and VRF (where applicable) with your own, and copy/paste the script into your IOS or NX-OS based device.


foreach address {

} {ping $address re 2

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Port listener / firewall rule tester

Have you ever needed to test if a particular firewall rule is enabled and actually functioning as expected? Of course you had! A great friend and a colleague passed this gem along to me that allows you to create a simple ‘port listener’ on any Windows machine using PowerShell.


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Best resources for learning Networking


After completing two CCIEs and numerous other certifications over the past 10+ years, I can certainly say that I have been through my fair share of training.  As many fellow CCIEs can probably appreciate, learning never stops, not even with two CCIEs, so I continue to go through training from different vendors and OEMs on different products.
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Technical and Non-Technical lessons learned from SDN implementation.

SDN implementation from any vendor is a big undertaking.  Unlike traditional networks, where lifecycle activities individually within network, compute, storage or security teams can happen in fair bit of isolation from each other, SDN implementation requires all teams, especially network, compute, application and security teams, to work more closely with each other than ever before.



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Practical Guide to getting started with Software Defined Networking (SDN)

The wonderful world of Software Defined Networking (SDN) is here.  If you are a networking professional, it’s best to embrace it with both arms open.

What is SDN?  How can I practically get started with SDN?  What are some good free and inexpensive resources to learn about all the different SDN solutions?  Which SDN solutions should I focus on in particular?

There are no 100% right or wrong answers to these questions, however, I will attempt to answer these questions based on the approach to SDN I am taking myself.

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