Common operational misconceptions

Paul Graydon paul at
Fri Feb 17 18:32:34 UTC 2012

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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