Re: OSPF SHAM-LINK

I had already increased the cost of the back door link very high.

Still the ospf is preferring to go through the back door link

--- On Mon, 3/29/10, Joe Astorino <jastorino_at_ipexpert.com> wrote:

From: Joe Astorino <jastorino_at_ipexpert.com>
Subject: Re: OSPF SHAM-LINK
To: "Abiola Jewoola" <biola_y2k_at_yahoo.com>
Cc: "Ahmed Ejaz" <aahmedejaz_at_gmail.com>, ccielab_at_groupstudy.com
Date: Monday, March 29, 2010, 11:10 PM

Ahhh...yes well then that is a different story. Typically we see both
remote sites configured for area 0. In your case if both the backdoor link
and the sham-link learned routes are O IA all you should need to do is tweak
the OSPF metric by manipulating cost where necessary. Just remember that
cost is calculated by adding in the cost of your inbound link.

On Tue, Mar 30, 2010 at 1:39 AM, Abiola Jewoola <biola_y2k_at_yahoo.com> wrote:

>
>
> Find attached the configs on my PE routers.
>
> The process id is the same and i also include the same domain-id . but the
> routes still comes as IA. i guess because the PE routers area pairing with
> CE routers with different areas.
>
>
>
> --- On *Mon, 3/29/10, Ahmed Ejaz <aahmedejaz_at_gmail.com>* wrote:
>
>
> From: Ahmed Ejaz <aahmedejaz_at_gmail.com>
> Subject: Re: OSPF SHAM-LINK
> To: "Joe Astorino" <jastorino_at_ipexpert.com>
> Cc: "Abiola Jewoola" <biola_y2k_at_yahoo.com>, ccielab_at_groupstudy.com
> Date: Monday, March 29, 2010, 9:57 PM
>
>
> I guess the ospf process which you are redistributing into bgp requires a
> domain id, that is the reason it is treating it as an IA route. Please add
a
> domain id on both the sides and the routes should come up as O routes then
> you can modify the cost to not prefer the sham link.
>
> HTH
> Ahmed
>
> On Tue, Mar 30, 2010 at 7:43 AM, Joe Astorino
<jastorino@ipexpert.com<http://mc/compose?to=jastorino@ipexpert.com>
> > wrote:
>
>> OSPF routes coming over the sham-link should be regular O routes
>> (intra-area) and thus should be preferred over O IA routes...post your
>> configurations something does not seem right about that.
>>
>>
>>
>> On Mon, Mar 29, 2010 at 10:35 PM, Abiola Jewoola
<biola_y2k@yahoo.com<http://mc/compose?to=biola_y2k@yahoo.com>>
>> wrote:
>> > Hello G.S
>> >
>> > How can i make ospf prefer to forward route routes via ospf sham-link.
>> The
>> > sham link has has a cost of 10 and the routes are coming as IA routes
>> across
>> > the MPLS backbone
>> >
>> > The router is preferring the backdoor link even when i have increased
>> the cost
>> > as high as 65000. The routes are also advertised as IA routes.
>> >
>> > Regards,
>> > Abiola
>> >
>> >
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>> >
>>
>>
>>
>> --
>> Regards,
>>
>>
>>
>> Joe Astorino - CCIE #24347
>> Sr. Technical Instructor - IPexpert
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Regards,
Joe Astorino - CCIE #24347
Sr. Technical Instructor - IPexpert
Mailto: jastorino_at_ipexpert.com
Telephone: +1.810.326.1444
Live Assistance, Please visit: www.ipexpert.com/chat
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IPexpert is a premier provider of Self-Study Workbooks, Video on Demand,
Audio Tools, Online Hardware Rental and Classroom Training for the Cisco
CCIE (R&S, Voice, Security & Service Provider) certification(s) with
training locations throughout the United States, Europe, South Asia and
Australia. Be sure to visit our online communities at
www.ipexpert.com/communities and our public website at www.ipexpert.com
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