[149943] in North American Network Operators' Group
Re: Common operational misconceptions
daemon@ATHENA.MIT.EDU (Paul Graydon)
Fri Feb 17 01:51:17 2012
Date: Thu, 16 Feb 2012 20:50:11 -1000
From: Paul Graydon <paul@paulgraydon.co.uk>
To: nanog@nanog.org
In-Reply-To: <5AD4C80D-425E-4CD0-B661-CF4F359A3D00@tzi.org>
X-SA-Exim-Mail-From: paul@paulgraydon.co.uk
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
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
