[j-nsp] ISIS-OSPF Redistribution Questions

[Walaa Abdel razzak]

Hi 

If I did this, then R6 or R7 will prefer datacenter routes through R5 bcoz they r coming with lower preference than ISIS routes which make sub-optimal routing.


Best Regards,
Walaa Abdel Razzak

-----Original Message-----
From: Hoogen [mailto:hoogen82 at gmail.com]
Sent: Sat 07/11/2009 22:38
To: Walaa Abdel razzak
Cc: juniper-nsp at puck.nether.net
Subject: Re: [j-nsp] ISIS-OSPF Redistribution Questions
 
Hi,

Your scenario looks like a complete opposite of what we have in the case
study, from what you have mentioned here.. The solution would be that on R6
and R7 you set the ospf external-preference to be lower than 149.. This
would make the def route from OSPF more preferred.

set protocols ospf external-preference 148 <-- Make the nssa def route
preference on R6 and R7 to be lower than that received from the ISIS DC
router.

-Hoogen

2009/11/7 Walaa Abdel razzak <walaaez at bmc.com.sa>

> Hi Experts
>
>
>
> If you have area 2 nssa receiving default route from the ABR with metric
> 150, two routers R6, R7 are sending this default route to ISIS level 1
> router in the DC. The L1 external preference are modified on R6, R7 to be
> 149. This is to prefer routes coming from ISIS than OSPF. The problem is
> that DC router resend the default route from R6 to R7. R7 see it with
> preference of 149 and the default route is coming from OSPF is 150 so it
> prefers the ISIS which cause non-optimal routing. Any ideas to solve this
> issue without making modification on the DC router?
>
>
>
> Sample config:
>
>
>
> R6 or R7 config.:
>
> --------------------
>
> isis {
>
>    export senddefault;           --------à send default to the ISIS router
>
>    level 2 disable;
>
>    level 1 external-preference 149;
>
>    interface fe-1/3/1.23;
>
>    interface lo0.6;
>
> }
>
> ospf {
>
>    export fromisis;                 --------à redistribute routes from ISIS
>
>    area 0.0.0.2 {
>
>        nssa;
>
>        interface lo0.6;
>
>        interface fe-1/3/0.20;
>
>        interface fe-1/3/1.16;
>
>        interface fe-1/3/1.23 {
>
>            passive;
>
>        }
>
>    }
>
> }
>
>
>
> DC:
>
> -----
>
> isis {
>
>    export static-isis;
>
>    level 2 disable;
>
>    interface fe-1/3/0.23;
>
>    interface fe-1/3/0.24;
>
> }
>
>
>
> BR,
>
> Walaa Abdel Razzak
>
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