At 7:03 PM +0000 5/22/02, Cisco Nuts wrote:
>Could you elaborate on the "backbone engineering is at a level far
>more specialized and complex than the CCIE level, and there haven't
>been formalized ways to learn it."
>
>I would love to know more about what you actually mean?
>
>Thank you.
>
>Regards.
>
:-) well, my book on the subject, "Building Service Provider
Networks," should be about to ship.
Seriously, let's talk about several areas, beginning with BGP. Every
BGP scenario I've seen or or heard of in the CCIE context, at best,
looks at an extremely simple configuration with rules NEVER used in
the real world. A few contrasts:
-- in the real world, it's VERY rare to redistribute between a dynamic IGP
and BGP. Sure, there are exceptions, but they are VERY carefully chosen.
A provider backbone CANNOT survive having 100,000-plus routes in its
IGP, nor should it.
-- In provider use, the main purpose of the IGP (or multiple instances of an
IGP) is to maintain connectivity among BGP routers. You may have a
separate IGP instance for each POP or group of POPs.
-- To connect customers, there is MUCH more use of static and default routes.
You could not possibly run a provider network with the CCIE lab rule of
no statics or defaults.
-- AS paths are longer and more complex than you can create with six or
so routers.
-- There's a HUGE amount of things to be concerned with that aren't strictly
configuration, such as justifying/obtaining/managing address space,
intercarrier relationships involving both economics and cooperative
troubleshooting, DNS management, protecting against distributed denial
of service, etc.
-- BGP communities are far more important than in typical scenarios.
You need to know why and when to set up your own, learn the values of
communities set by other AS and under what circumstances you should act
on them, etc.
-- You may be dealing literally thousands of routers in your own network,
interconnected with thousands of enterprise networks. You may also have
a complex ATM, SONET, MPLS, or other intelligent sub-IP technology that
must coordinate with the IP.
-- There's a different viewpoint on convergence. It's generally accepted
among large providers and researchers that the worldwide "BGP table"
never truly converges -- changes come too fast. We have to work in that
environment.
-- Customers frequently multihome in ways that require coordinating between
their providers, even when those providers are competitors.
-- As opposed to an enterprise network where SOMEBODY is in control, the
provider space involves cooperative anarchy. One AS fouling up its
configuration can and has had worldwide effects.
These are just a start. There are other people that can comment on
some of the differences. Peter van Oene (yes, I'm volunteering you)
is one with lots of good experience. There are others, and this
actually might be an interesting thread.
--
"What Problem are you trying to solve?"
***send Cisco questions to the list, so all can benefit -- not
directly to me***
********************************************************************************
Howard C. Berkowitz [EMAIL PROTECTED]
Chief Technology Officer, GettLab/Gett Communications http://www.gettlabs.com
Technical Director, CertificationZone.com http://www.certificationzone.com
"retired" Certified Cisco Systems Instructor (CID) #93005
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