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Re: Common operational misconceptions
From: Paul Graydon <paul () paulgraydon co uk>
Date: Fri, 17 Feb 2012 08:32:34 -1000

On 02/17/2012 04:29 AM, Leo Bicknell wrote:
In a message written on Thu, Feb 16, 2012 at 08:50:11PM -1000, Paul Graydon wrote:
At the same time, it's shocking how many network people I come across
with no real grasp of even what OSI means by each layer, even if it's
only in theory.  Just having a grasp of that makes all the world of
difference when it comes to troubleshooting.  Start at layer 1 and work
upwards (unless you're able to make appropriate intuitive leaps.) Is it
physically connected? Are the link lights flashing? Can traffic route to
it, etc. etc.
I wouldn't call it a "misconception", but I want to echo Paul's
comment.  I would venture over 90% of the engineers I work with
have no idea how to troubleshoot properly.  Thinking back to my own
education, I don't recall anyone in highschool or college attempting
to teach troubleshooting skills.  Most classes teach you how to
build things, not deal with them when they are broken.
The Cisco CCNA syllabus used to emphasise the layer 1->7 approach to troubleshooting. Not sure if they still do, or if trainers even bother to mention it (mine did back when I did it several years ago)

The basic skills are probably obvious to someone who might design
course material if they sat down and thought about how to teach
troubleshooting.  However, there is one area that may not be obvious.
There's also a group management problem.  Many times troubleshooting
is done with multiple folks on the phone (say, customer, ISP and
vendor).  Not only do you have to know how to troubleshoot, but how
to get everyone on the same page so every possible cause isn't
tested 3 times.
Never trust what you can't prove yourself, that includes vendors and customers. Every now and then I forget this and find hours later that I've wasted a whole bunch of time because I trusted when someone said something that it actually was the case. It's really often better to test something a third time even if Vendor and Customer tell you something is a particular way.

I think all college level courses should include a "break/fix"
exercise/module after learning how to build something, and much of that
should be done in a group enviornment.

Definitely. I've learnt more in my time from breaking things than I've ever learnt setting them up; however the education system is focused on breadth of knowledge, not depth. Students are expected to be able to regurgitate ridiculous amounts of facts and figures, so that they pass standardised tests, not understand how to actually use them.


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