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Re: Common operational misconceptions
From: Jack Bates <jbates () brightok net>
Date: Fri, 17 Feb 2012 09:14:00 -0600

On 2/17/2012 1:05 AM, Carsten Bormann wrote:
On Feb 17, 2012, at 07:50, Paul Graydon wrote:

what OSI means

Yet another common misconception popping up:

-- You can talk about the OSI model in the present tense

(That said -- yes, it is still useful as a set of simple terms for certain combinations of functions.
It is also still useful as a way to calibrate your gut feeling of what is going on in a network.
Just never expect OSI terms to have a precise meaning in today's networks.
1978 is now a third of a century ago...
If you need precision, you need to spell out what you mean in today's terms.)

Actually, I find it makes a perfect troubleshooting guideline in today's world; at least up to layer 4. I'm not saying it's a perfect match to troubleshooting a variety of MPLS problems, but it is a reminder that there are dependencies which must be checked.

In dealing with transport companies, the model is still a good representation of their service levels. It isn't uncommon to find their products defined as layer 2 services (ranging from tdm/sonet services to ethernet switching services), layer 3 services (often handled by their ISP department), and MPLS services (which can range from p2p transport to l3vpn).

Which brings up my final point. Until we quit naming things l2vpn or l3vpn, OSI still applies. :P


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