From: Victor Cappuccio (cvictor@protokolgroup.com)
Date: Fri Oct 14 2005 - 21:58:23 GMT-3
Landon,
Ok let me see if I get the picture here..
When you redistribute in R4 to OSPF you are going to have an external
(e2, e1) ospf route that you can TAG.
This route is learnt by R3 via OSPF and EIGRP.. but by means of the AD
then the route is going to be preferred via OSPF write?
If this is ok for you, then why not filtering at R3 using the TAG that
R4 set (or viceversas)?
also comes into my mind that I you can filter by means of the tag in the
mutual redistribution process at R3 and R4, also you can filter by the
type of the route that is external, Let me know your opinion..
Thanks for the clarification
Victor
Landon Fitts wrote:
>Victor,
>
>Yes, that is correct R3,R4, and R2 are in AS-1 running EIGRP.
>Also, R2 is in AS-2 running EIGRP with R1. The problem is how to
>prevent R3 and R4 from installing the redistributed AS-2 EIGRP
>routes in their routing table. The reason being is if this
>happens you will get a routing loop for the routes learned from
>AS-2, because R3 and R4 see the AS-2 routes as EIGRP External,
>and also sees those same routes via OSPF as OSPF External. You
>would want the path to networks in AS-2 to be via R2, but it will
>take the OSPF route via R5, because of the lower admin distance.
>Does that make sense? I used a "distribute-list in" under OSPF
>process at R3 and R4 for the AS-2 networks and that worked, but
>I wanted to know of any other methods. I tried using tags, but
>could not get that to work.
>
>I think my topology diagram got a bit jumbled. Here it is again:
>
> |-----R3-----|
>R1-----R2------| |-----R5
> |-----R4-----|
>
>
>
>Regards,
>Landon
>
>-----Original Message-----
>From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
>Victor Cappuccio
>Sent: Friday, October 14, 2005 8:26 PM
>To: Landon Fitts
>Cc: ccielab@groupstudy.com
>Subject: Re: EIGRP - OSPF Redistribution
>
>Hello Ladon, nice question to think about. Could you please can you clarify
>a little bit the problem R3, R3 and R4 are running EIGRP AS-1 between them
>??
>
>- R1 and R2 are running EIGRP AS-2 between them
>- R3, R3, and R4 are running EIGRP AS-1 between them
>- R3, R4, and R5 are running OSPF AREA-0 over FR between them
>- R2 is mutually redistributing EIGRP AS-1 & AS-2
>- R3 and R4 are mutually redistributing OSPF and EIGRP
>
>Do not get the topology yet
>My first thought are tags (but could you please clarify the problem) Thanks
>Victor.
>
>
>
>Landon Fitts wrote:
>
>
>
>>I have a question on the various methods available to prevent EIGRP
>>routes that are redistributed into OSPF at two different ASBRs from
>>being installed into the route table of those same ABSRs when relearned
>>
>>
>>from OSPF. I was able to use a "distribute-list <acl> in" under the
>
>
>>ospf process to successfully achieve this, but I couldn't get it to
>>work using a route-map on the redistribution statement matching on the
>>tagged eigrp networks. Using the route-map with tagging method, the
>>routing table would go back and forth between installing an E2 route
>>and a EX route on the ASBRs every time I cleared the route table.
>>
>>To make this clearer below is my topology:
>>
>>
>> |---R3-----|
>>R1-----R2-----SW-----| |-----R5
>><mailto:lafitts@cisco.com> |---R4-----|
>>
>>
>>Scenario:
>>- R1 and R2 are running EIGRP AS-2 between them
>>- R3, R3, and R4 are running EIGRP AS-1 between them
>>- R3, R4, and R5 are running OSPF AREA-0 over FR between them
>>- R2 is mutually redistributing EIGRP AS-1 & AS-2
>>- R3 and R4 are mutually redistributing OSPF and EIGRP
>>
>>Problem:
>>Networks from AS-2 will be seen as EIGRP external routes at R3 & R4, so
>>when these networks are relearned back from R5 via OSPF the route table
>>at R3 and R4 will install the E2 routes because of the lower admin
>>distance. This will not be a problem for the networks learned from
>>AS-1 via R2, because at R3 & R4 those networks will be seen as internal
>>EIGRP routes.
>>
>>Route Redistribution at multiple redistribution points has never been
>>an easy topic for me, but this scenario seems to add more
>>complications. Can any of you routing experts shed some light on this
>>for me?
>>
>>
>>Thanks,
>>Landon
>>
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