From: David Ham (ccieau@xxxxxxxxx)
Date: Tue May 14 2002 - 22:00:35 GMT-3
Here is my summary
When the routes in higher AD routing process domain
redistributed into Lower AD routing process domain.
Undesirable path selection occur.
Ie: RIP ( 120 )--> OSPF ( 110 ) ---> IGRP ( 100 )
-->E IGRP (90).
=====================================================
IGRP(100)/EIGRP (90 ) --- Don't need to anything --
EIGRP has external AD ( 170 ) for the external routes.
this external routes are less prefer so it will take
right path.
=====================================================
OSPF(110)/EIGRP(90) --- Don't need to anything ---
same reason as above
=====================================================
RIP(120)/EIGRP(90) --- Don't need to anythnig --- same
reason as above
======================================================
RIPv1&2(120)/OSPF (110 ) --- you can change the
distance of external ospf routes that has
redistributed from RIP process domain -- use distance
ospf external 121 ( higher value than 120 ) at ospf
process domain
=====================================================
RIPv1&2(120)/IGRP(100) ---
use route-map : see example 1 -- same concept
or use distribute-list : see example 2 -- same concept
======================================================
OSPF (110)/ IGRP (100)
use route-map : see example 1 --same concept
or use distribtue-lsit : see example 2 -- same concept
------------------------------------------------------
example1
1: see the igrp routes and Apply access-list include
directly connected igrp domain routes
sh ip route-- see igrp routes ( before the
redistribution )
access-list 1 permit 132.110.3.0 0.0.0.255
access-list 1 permit 132.110.4.0 0.0.0.255
access-list 1 permit 132.119.20.0 0.0.0.255 ----
connected subnet
2: Create route-map
route-map only-igrp permit 10
match ip add 1
route-map no-igrp deny 10
match ip add 1
route-map no-igrp permit 20
3: Apply on redistribution
router ospf 1
redistribute igrp 1 subnet route-map only-igrp
router igrp 1
redistribute ospf 1 route-map no-igrp
------------------------------------------------------
Example 2
1. create access-list
access-list 10 permit ( IGRP routes that need to
distribute out to other routing domain )
access-list 10 deny any.
2. apply on igrp routing process
router igrp 1
distribute-list 10 in
You need to put filter at redistuting routers
interface in lower AD routing protcol domain
------------------------------------------------------
Lastly you can use tag at the multipoint mutual
redistribution points. ( the routing protocols
supporting tags are EIGRP, OSPF, RIP v2, BGP ) Not
IGRP and RIP v1
Please let me know if you see any misunderstanding.
Regards,
David Ham
Data Specialist
Singtel OPTUS
--- Eric Drewitz <Eric.Drewitz@oomc.com> wrote: > It
seems to me that if you have multiple points of
> redistribution you would have to use acl or the
> distance command w/acl to achieve proper
> redistribution. If you are only mutually
> redistributing on 1 router you really dont have to
> worry too much about feedback. (assuming split
> horizon is on) Comments?
>
> -----Original Message-----
> From: Neil G. Legada [mailto:nglegada@hotmail.com]
> Sent: Monday, May 13, 2002 2:01 AM
> To: Michael Snyder; 'Ahmed Mamoor Amimi'
> Cc: ccielab@groupstudy.com
> Subject: Re: Just for a confirmation !! on
> redistribution
>
>
> Was discussed on this thread also:
>
>
http://www.groupstudy.com/archives/ccielab/200201/msg01743.html
>
>
> Regards,
>
>
> ----- Original Message -----
> From: "Michael Snyder" <msnyder@ldd.net>
> To: "'Ahmed Mamoor Amimi'" <mamoor@ieee.org>
> Cc: <ccielab@groupstudy.com>
> Sent: Monday, May 13, 2002 1:05 AM
> Subject: RE: Just for a confirmation !! on
> redistribution
>
>
> > Yes,
> >
> > My understanding is that you don't want routes
> coming from r3 via r2 to
> > r1 to be passed back to r3, and also routes coming
> from r1 via r2 to r3
> > should never be passed back to r1.
> >
> > Ok, you can filter these via subnet, but why?
> That's the hard way.
> >
> > Both eigrp and ospf support route tagging. Just
> tag the route the first
> > time it transverses r2, and block it from
> reentering r2.
> >
> > You can find examples of redistribution route
> tagging in the archives.
> >
> >
> >
> >
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com
> [mailto:nobody@groupstudy.com] On Behalf Of
> > Ahmed Mamoor Amimi
> > Sent: Sunday, May 12, 2002 4:27 AM
> > To: ccielab@groupstudy.com
> > Subject: Just for a confirmation !! on
> redistribution
> >
> > Morning Guys !!
> > Is my way of redistribution correct please
> confirmed after reading this
> > :
> >
> > r1------(eigrp)-------r2------(ospf)-------r3
> >
> > r1 running eigrp
> > r2 running eigrp and ospf
> > r3 running ospf
> >
> > r1 have routes 1,2,3
> > r3 have routes 4,5,6,7,8,9,10,11,12,13,14,15
> (lots of routes)
> >
> > on r2 i will redistribute and be specific that no
> route loop is formed
> > so i
> > use route-map in redistribution.
> >
> > i made a route-map on r2 which only calls eigrp
> routes
> > route-map eigrp
> > match ip address 1
> >
> > access-list 1 permit 1
> > access-list 1 permit 2
> > access-list 1 permit 3
> >
> > for ospf i dont make access-list but instead i
> denied 1,2,3 and allow
> > others ,
> > like :
> > route-map ospf deny 10
> > match ip address 1
> >
> > route-map ospf permit 20
> >
> > ospf route-map is calling that same access-list
> that is made for eigrp
> > but
> > here this access-list is denied and rest are
> permitted.
> >
> >
> > Is this the correct way or i should make an
> access-list for ospf and
> > call
> > 4,5,6,7,8,9,10,11,12,13,14,15 (takes lot of time)
> and apply it to the
> > ospf
> > route-map.
> >
> > Just want to make sure .....
> >
> > waiting for comments.
> >
> > -Mamoor
> >
>
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