From: Schulz, Dave (DSchulz@dpsciences.com)
Date: Tue Dec 06 2005 - 09:41:16 GMT-3
You are correct, Venkat. Thanks for pointing that out. Here is the
correction. Good advice on using the debug ip routing to find the loops.
router ospf 1
redistribute eigrp 100 route-map E2O subnets
router eigrp 100
redistribute ospf 1 route-map O2E metric 100000 1000 255 1 1500
!
!
route-map E2O deny 10
match tag 110 (I use the tag that has the same admin distance #)
!
route-map E2O permit 20
set tag 90
!
route-map O2E deny 10
match tag 90
!
route-map O2E permit 20
set tag 110
!
-----Original Message-----
From: Venkataramanaiah.R
To: Schulz, Dave
Cc: Serge N'GBESSO; nobody@groupstudy.com; ccielab@groupstudy.com
Sent: 12/6/2005 1:21 AM
Subject: Re: Controling mutual redistribution loops
May be you meant to set the tags and not match them in your permit 20
statements...
If you only match them, where would you set them exactly..
A very important tip to spot the routing loops is to enable debug ip
routing. If you see too many debug messages even after the routing
protocol is supposed to have converged, then you certainly have some
routing loop somewhere..
-Venkat
On 12/4/05, Schulz, Dave <DSchulz@dpsciences.com
<mailto:DSchulz@dpsciences.com> > wrote:
Serge -
The rule of the thumb (I think, at least one of them) on mutual
distribution
...is not redistribute routes back into the area that they originally
came
from (causing a loop). IMHO, the best way to do this is through tags,
though
you can use specific route....but these are little less
administration-friendly, since if the routes change, so do your
access-lists/route-maps. Also, watch out for your metrics (not as big
in ospf
as in eigrp). Here is an example that I have....hope this
helps....(mutual
redistribution from ospf to eigrp). Also, I am doing this for memory,
so it
may look different on your router. Please correct me if I missed
something.
------------------------
router ospf 1
redistribute eigrp 100 route-map E2O subnets
router eigrp 100
redistribute ospf 1 route-map O2E metric 100000 1000 255 1 1500
!
!
route-map E2O deny 10
match tag 110 (I use the tag that has the same admin distance #)
!
route-map E2O permit 20
match tag 90
!
route-map O2E deny 10
match tag 90
!
route-map O2E permit 20
match tag 110
!
Note: I like to use the tag that has the same admin distance where the
route
originally came from, just to keep it straight....but this your choice.
-----Original Message-----
From: nobody@groupstudy.com <mailto:nobody@groupstudy.com>
To: ccielab@groupstudy.com <mailto:ccielab@groupstudy.com>
Sent: 12/4/2005 9:23 AM
Subject: Controling mutual redistribution loops
Hi all,
I'm always afraid when it comes to spoting mutual redistribution loops
!!
What are the rules of tumbs for visualising the potential loops ?
What is the logic behind this ?
Does packet tagging always block the redistribution loops ?
what is the implementation logic ?
Thx for your answers !
Serge R. N'GBESSO
serge.ngbesso@bnpparibas.com <mailto:serge.ngbesso@bnpparibas.com>
Security Consultant
CCDA, CCSP, CCIE:Security,
Certified Etichal Hacker.
www.1000club.com/club/japon/ <http://www.1000club.com/club/japon/>
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