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Re: Common operational misconceptions
From: Paul Graydon <paul () paulgraydon co uk>
Date: Thu, 16 Feb 2012 20:50:11 -1000

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


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