From: Cielieska Nathan (ncielieska@gmail.com)
Date: Sat Feb 16 2008 - 01:55:04 ARST
Thanks for the input Darby. It is much appreciated.
Have a great weekend,
Nate
On Feb 15, 2008, at 10:27 PM, Darby Weaver wrote:
> Hmmm...
>
> 1. Learn to look at a topology
> - Look for Layer 1 aka Physical Loops
> - Look for Layer 2 aka Bridging Loops (SPT helps
> here)
> - Look for Layer 3 aka Routing Loops
>
> When I say look at a topology, I mean draw a diagram
> and touch the interfaces. Somehow this seems to help.
>
>
> 2. Next, ask yourself if you have a "Redistribution
> Condition" - do you even have the possibility of
> having a routing loop? Yes/No If you do then which
> protocol has a higher AD and which protocol has a
> lower AD? This is crucial to understanding how you
> are going to deal with the routing loop.
>
> Remember some protocols naturally have an interior AD
> and an exterior AD. One in particular does not: RIP.
> Stop for a minute and think of the options.
>
> RIP | RIP
> RIP | EIGRP
> RIP | OSPF
> RIP | BGP
>
> EIGRP | EIGRP
> EIGRP | OSPF
> EIGRP | BGP
> EIGRP | RIP
>
> OSPF | OSPF
> OSPF | EIGRP
> OSPF | BGP
> OSPF | RIP
>
> See anything special here? Remember AD is key. Learn
> how to match all route use distribute lists,
> route-maps and AD in general as tools to influence or
> even mark in the case of Route-Tagging various routes.
>
> NMC has a nice little paper on this issue and it is
> worth a trip to their website to find that gem of a
> pdf.
>
> My best advice is to take each protocol variation and
> play with it. Using the tools and techniques
> recommended by your favorite vendor.
>
> Better to meet the enemy on your own terms. It may
> take a good afternoon or so and or a couple of days
> but if you do it methodically you should have it in a
> relatively short amount of time.
>
>
> 3. logging console
> logging buffered 100000
> logging on
> debug ip routing
> log adjacencies per protocol
>
> Let the router be the one to tell you that you are
> having issues. Your job is to be more aware of the
> tools you have to be able to influence the process.
>
>
> Look at this pdf and lab it up. Thanks for NMC for an
> example I know I use when my memory wants to fail me
> on the matter or things do not seem to make sense any
> more.
>
> http://netmasterclass.net/site/articles/A%20Scenario%20with%
> 20Multiple%20Redistribution%20Points.pdf
>
>
>
> --- Scott Vermillion <scott_ccie_list@it-ag.com>
> wrote:
>
>> Hey Nate,
>>
>> I spent a disproportionate amount of my study time
>> trying to get to that
>> magical place where I could stare down any
>> redistribution task of any
>> complexity and just see what was going to happen
>> underneath the hood (bonnet
>> for our international list members). Never
>> happened. What did happen was
>> that 'debug ip routing' became a really good friend
>> of mine. Also, just
>> running full speed and smacking myself into that
>> wall over and over again
>> helped. I'm now to the point where I feel I can
>> solve any redistribution
>> task of any complexity - GIVEN ENOUGH TIME to do so.
>> But sometimes it's so
>> subtle that you're not likely to see it until you
>> get some results from your
>> debug. There were a few times when I even adjusted
>> the AD of a given
>> protocol or something like that just to see what, if
>> any, impact it might
>> have. That may or may not have sent me in a new
>> direction.
>>
>> Don't let these discourage you like I did. Keep at
>> it. Realize that no
>> sane network engineer would really do what some of
>> these lab scenarios are
>> calling for. They're just meant to expose various
>> (often times unintuitive)
>> behaviors that you might at some point encounter.
>>
>> Regards,
>>
>> Scott
>>
>>
>> -----Original Message-----
>> From: nobody@groupstudy.com
>> [mailto:nobody@groupstudy.com] On Behalf Of
>> Cielieska Nathan
>> Sent: Tuesday, February 12, 2008 7:45 PM
>> To: ccielab certification
>> Subject: Quick and dirty way to identify issues
>> regarding redistribution
>>
>> Guys,
>>
>> So i ran into a brick wall last night which is IE's
>> Workbook 3 Lab 8
>> (Thanks Brians!). I thought i was really starting to
>> get into the
>> groove and this took me down a peg.
>>
>> With that said i actually ran into the section near
>> the end where the
>> redistribution happened. I was sitting in front of
>> my routers just
>> absolutely dumfounded and saved the configs and quit
>> the lab early.
>>
>> I have listened to a few VOD's, did all of the basic
>> lab scenarios
>> regarding redistribution and even can deal with
>> redistribution in a
>> typical "i have two routers and they both have EIGRP
>> and OSPF talking
>> and you need to redistribute on both questions", so
>> i think i got the
>> BASIC jist of it down.
>>
>> Is there a methodolgy the truly experienced use to
>> see the big
>> picture with extremely complex redistribution. Maybe
>> like a playbook
>> one uses. I have read some folks tag their
>> redistributed routes,
>> others will allow redistribution on one router and
>> immediately
>> disallow on the second.. maybe a combination of
>> both.
>>
>> Any suggestions on getting a truly in-depth
>> understanding of
>> redistribution would be extremely helpful right now.
>> If that means
>> labbing up some silly scenarios maybe someone can
>> share a template of
>> what i should be labbing up?
>>
>> How did you really learn redistribution.
>>
>> Regards,
>> Nate
>>
>>
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