From: Scott Morris (smorris@ipexpert.com)
Date: Tue Oct 02 2007 - 16:54:19 ART
I don't think there's any simple answer as each
scenario/lab/network/experience is a little different.
Most of the time, I will tag routes when I redistribute. Whether I really
need to or not is irrelevant. I can monitor where a route came from at any
time, and IF I have to filter anything, it's less work to implement it
'cause the tag is already there.
I also will typically tag with the tag number equal to the AD of the
originating protocol. Again, just simple things to bring consistency into
play.
But watch what your lab tells you. Watch the results of "debug ip routing"
and determine whether you need to care or not! Simple redistribution
doesn't need to be that fancy. I always encourage people to enable "debug
ip routing" on all devices before you start redistribution. While
practicing, you should be able to anticipate what things you'll see and
where you will see them. If you are surprised by anything, figure it out!
But you don't want to wait until your last 30 minute check of things to
discover that someplace along the way you screwed half of your routing
table! That makes a very expensive lunch you just had!
HTH,
Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, JNCIE-M
#153, CISSP, et al.
CCSI/JNCI-M/JNCI-ER
VP - Technical Training - IPexpert, Inc.
IPexpert Sr. Technical Instructor
A Cisco Learning Partner - We Accept Learning Credits!
smorris@ipexpert.com
Telephone: +1.810.326.1444
Fax: +1.810.454.0130
http://www.ipexpert.com
-----Original Message-----
From: Mohamed M Moustafa [mailto:mmma@gawab.com]
Sent: Tuesday, October 02, 2007 3:27 PM
To: Scott Morris
Cc: 'Brian Dennis'; ccielab@groupstudy.com
Subject: RE: Mutual redistribution and loop prevention
Hi Scott,
Thank you very much, i'll make sure to eliminate all those tedious routing
loops, but one last question if i may, if i was told to use AD, and i used a
conjunction of AD and tagging + filtering, am i ok with that or what, as
most of the scenarios won't go fine with just manipulating the AD.
Thank you again both of you Brian and Scott for your influence in the field.
BR,
Mohammed Mahmoud.
Scott Morris <smorris@ipexpert.com> wrote on 2 Oct 2007, 05:28 PM:
Subject: RE: Mutual redistribution and loop prevention
>While optimal routing is not a requirement, I'd venture to say that
>pure reachability is!
>
>
>Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713,
>JNCIE-M #153, CISSP, et al.
>CCSI/JNCI-M/JNCI-ER
>VP - Technical Training - IPexpert, Inc.
>IPexpert Sr. Technical Instructor
>
>A Cisco Learning Partner - We Accept Learning Credits!
>
>smorris@ipexpert.com
>
>Telephone: +1.810.326.1444
>Fax: +1.810.454.0130
>http://www.ipexpert.com
>
>
>-----Original Message-----
>From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
>Mohamed M Moustafa
>Sent: Tuesday, October 02, 2007 2:34 AM
>To: Brian Dennis
>Cc: ccielab@groupstudy.com
>Subject: Re: Mutual redistribution and loop prevention
>
>Hi Brian,
>Thank you very much for your response, but do i have to insure full
>reachability even for example for routes received from the BB routers,
>and prevent all kind of routing loops, even if i am not asked to, what
>is scope of full reahability.
>BR,
>Mohammed Mahmoud.
>Brian Dennis <bdennis@internetworkexpert.com> wrote on 2 Oct 2007,
>08:12
>AM:
>Subject: Re: Mutual redistribution and loop prevention Do whatever you
>need to ensure full reachability. If a routing loop is causing you to
>not have full reachability then resolve it.
>HTH,
>Brian Dennis, CCIE4 #2210 (R&S/ISP-Dial/Security/SP)
>bdennis@internetworkexpert.com Internetwork Expert, Inc.
>http://www.InternetworkExpert.com
>Toll Free: 877-224-8987
>Direct: 775-745-6404 (Outside the US and Canada) On Oct 2, 2007, at
>5:12 AM, Mohamed M Moustafa wrote:
>Hi everybody,
>I heard a lot about over thinking tasks in the exam, and i've a small
>question to know if i am over thinking this issue or not, it is
>regarding mutual redistribution and loop prevention.
>Lets assume that i was asked to do a lot of mutual redistributions,
>which eventually will cause routing loops, and after wards i was asked
>to prevent certain routing loops at certain points in the network, does
>this mean that i don't have to prevent all routing loops at all points
>in the network, just the loops i was asked to prevent, or do i have to
>prevent all routing loops in the topology, which is sometimes
>cumbersome.
>BR,
>Mohammed Mahmoud.
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