Software-Defined Networks .. A Primer


SDN, Software-Defined Networking, the trending technology that some friends/colleagues of mine like to refer to it as “Still Does Nothing”. Let’s see if it does some thing. SDN has been a market hype for few years now.  Out of laziness, I ignored it in the beginning then I had to catch up a bit later and learn what was exactly going on.  From who I know many engineers have taken the same path and are still ignoring SDN, probably out of the feeling that we have enough to learn something new. Lately, SDN has been reduced to a buzzword that …

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Troubleshoot#2: Core Dumps for Network Engineers


Got a core dump file, please contact your TAC engineers for further support ! This is the common statement that we all see on vendors’ websites and in their recommendations and it definetly is true.  The reason is that a core dump file contains information that requires deep knowledge of the code of the cored application to make use of it. However, this doesn’t mean that core dump files are totally “this is not your business” thing. Network operations teams can use core dumps strategically to help their vendor’s support find and fix their problems quicker. I will try to …

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Cheat: your portable memory bank

How often do you find yourself scratching your head, trying to remember a command that you knew by heart but just can’t remember when you need it most? It happens to me quite often. Probably because I am aging or may be there is too much stuff in my brain attic. But I found a solution to that and it’s called Cheat. Cheat is a beautiful light weight piece of software .. Here is the excerpt from the Github documentation page for what it does.   “Cheat allows you to create and view interactive cheat sheets on the command-line. It was designed …

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Making Sense of Broadband networks: PPPoE Explained

A bit of background First .. PPPoE stands for Point to Point over Ethernet and is the successor of PPPoA. PPPoE is simply a method of encapsulating PPP packets into Ethernet frames. The standard is defined in RFC2516 . IPoE is growing very quickly but as far as I can tell PPPoE is still very widely deployed model in broadband networks. PPP protocol is a very mature protocol that was originally implemented to create and maintain direct connections between two nodes. PPP is such a protocol that provides many features but the one that is most interesting to broadband providers is the ability …

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Understand MTU and MRU – The Full Story

MTU or Maximum transmission unit is a topic that pops up every once in a while in different discussions. Although it’s a simple concept, it causes a lot of confusion specially for those who are new to the field. MTU typically becomes an issue of concern during network changes, like adding new vendors equipment or upgrading to a new software. One reason for that is the difference in  implementations used by different vendors or even between different OS versions or equipment  from the same vendor. Here is an example for such confusion  MTU and ping size confusion. On the other …

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Troubleshoot#1: Correlation vs Causation

Network problems can be as simple as follows: Ping neighbor. 100% packet loss. Check network interface, it’s down. Change SFP and you are done, problem solved   But they can also be complex; really complex .. In the past few years, I have had the unplanned privilege to see some of the shi**iest networking problems on earth. Not because I am an unlucky bastard but simply because I am in the position that if it reaches me, then it’s fairly complex. Dealing with such scenarios have taught me some good lessons that are not necessarily limited to networking or IT. …

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