From: DAN DORTON (DHSTS68@xxxxxxxxxxxxxxx)
Date: Thu Mar 07 2002 - 11:18:32 GMT-3
The easiest thing to do is create another virtual-link across the area recievin
g the IA routes & bring area 0 there too.
Once you do that & both routes are seen as O routes the cost will take effect.
Otherwise the O route will always be preffered over the IA route.
Trust me I beat the hell out of a similar scenario (Although quite a bit more c
omplex.) for about a week & nothing truly operated properly until I meshed the
Virtual-Links.
Dan
>>> <RSiddappa@NECBNS.com> 03/06/02 03:35PM >>>
This is agin one more similar problem of Intra area rouete to Interarea
route.
if u look at the routing table it is prefering the
route Marked with O over IA.
One of the tricsk u can try is to creat one more OSPF process in router R5
and put the ISDN interafce that roting process and then redisritbuting that
in to the main OPSF process at R5. The the routes thorugh ISDN will appera
as External rouets and R5 will prefere, the serail link.
this is the similar solution given found by Chau parry for one of the same
kind of problems and credit shoudl go to him if it works.
I Have not tested.
R.
-----Original Message-----
From: Bob Sinclair [mailto:bsin@erols.com]
Sent: Wednesday, March 06, 2002 1:16 PM
To: Paul Borghese
Cc: ccielab@groupstudy.com
Subject: Re: Virtual Links and Backup Interfaces in OSPF
Just a thought: what if you raised the admin distance for ospf routes
learned from the router on the other side of the BRI? I have had some
success doing this with ospf.
----- Original Message -----
From: "Paul Borghese" <paul98@prodigy.net>
To: <ccielab@groupstudy.com>
Sent: Wednesday, March 06, 2002 1:34 PM
Subject: Virtual Links and Backup Interfaces in OSPF
> Hi,
>
> I have created a practice scenario using the following setup (OSPF
protocol):
>
> R1 is connected to R2 and the connection is in Area 0. R2 is connected to
R5
> in Area 100. R5 has a backup ISDN link to R1. I made this backup Link
area
> 101 and created a virtual link through area 101 to connect Area 100 in
case
> the connection to R2 ever went down. R1 has a route (172.16.1.0) which is
in
> Area 0.
>
> The problem I am having is R5 always prefers to use the BRI interface to
get
> to 172.16.1.0 instead of using the connection to R2. I even set the cost
of
> the BRI interface to be 10x that of the R2 connection. Here is the
results on
> R5:
>
> With the ISDN line active:
> 172.16.0.0/24 is subnetted, 1 subnets
> O 172.16.1.0 [110/10010] via 190.27.1.66, 00:52:04, Dialer0
>
> With the ISDN in Shutdown mode:
> 172.16.0.0/24 is subnetted, 1 subnets
> O IA 172.16.1.0 [110/943] via 190.27.1.33, 00:00:03, Serial4
>
> Notice with the ISDN active, the router prefers to use the Dialer
interface
> even though the metric is 10010 versus the Serial 4 interface with a
metric of
> 943! I believe this is because the route learned via the Dialer0
interface is
> an interior route and the route learned via the S4 interface is an
InterArea
> route.
>
> So is there any way to get R5 to prefer the S4 route with the Dialer
interface
> active? Of course one way to fix this would be to make the ISDN line
area
> 100 and dump the Virtual Link. But I am wondering if there is a way to do
it
> using the typology I created.
>
> Paul Borghese
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