Common operational misconceptions

[paul at paulgraydon.co.uk (Paul Graydon)]

On 2/16/2012 8:30 PM, Carsten Bormann wrote:
> On Feb 16, 2012, at 18:08, Jack Bates wrote:
>
>> It at first started with trying to explain that vlan based switching is not Layer-3. :(
> Ah, one of the greatest misconceptions still around in 2012:
>
> -- OSI Layer numbers mean something.
> or
> -- Somewhere in the sky, there is an exact definition of what is layer 2, layer 3, layer 4, layer 5 (!), layer 7
> or
> -- my definition is righter than yours
>
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.

Paul