Re: OSPF SHAM-LINK

I am pretty sure this is resolved -- Abiola and I took it off list and
got into the specific diagram / topology. Correct me if I'm wrong
Abiola.

On Fri, Apr 2, 2010 at 10:44 AM, Bryan Bartik <bbartik_at_ipexpert.com> wrote:
> Abiola,
>
> Can you diagram what you have? Perhaps there is something else wrong. When
> you shut the backdoor link down, does the route become accessible over the
> mpls vpn link?
>
> On Tue, Mar 30, 2010 at 7:24 AM, Abiola Jewoola <biola_y2k_at_yahoo.com> wrote:
>>
>> The whole idea is to make the sham-link preferable.
>>
>> The existing design is the the sites are in different ospf areas .
>>
>> like u said, if the ospf routes from both the mpls link and ospf are
>> coming
>> as IA we can tweak the cost.
>> That has been done and the routes still prefers to go via the ospf link
>> even
>> after a very high cost.
>>
>>
>>
>> --- On Tue, 3/30/10, 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: Tuesday, March 30, 2010, 3:09 AM
>>
>> Abiola,
>>
>> To summarize here -- If you have site 1 and site 2 linked up via MPLS and
>> also
>> via a backdoor link and both sites are in different areas then there is no
>> need to use a sham link in the first place. Both the backdoor and mpls
>> routes
>> will be O IA and you can simply tweak cost.
>>
>> Now, if you have site 1 and site 2 and they are both in the same area then
>> you
>> have a problem because the mpls learned routes will still show up as O IA
>> at
>> best, and the backdoor link will always be preferred. If you are saying
>> that
>> you have separate sites here then forget about the sham link and lets
>> focus on
>> manipulating the OSPF cost to get things to route the way you'd like.
>>
>>
>>
>> On Tue, Mar 30, 2010 at 5:46 AM, Joe Astorino <jastorino_at_ipexpert.com>
>> wrote:
>>
>>
>> Make both CE sites the same OSPF area
>>
>> On Tue, Mar 30, 2010 at 5:44 AM, Abiola Jewoola <biola_y2k_at_yahoo.com>
>> wrote:
>>
>> Yea,
>>
>> My sham is link up from both sides from the show ip ospf sham-link output
>> a
>>
>> And full from the show ip ospf nei output!
>>
>>
>>
>> --- On Tue, 3/30/10, 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: Tuesday, March 30, 2010, 2:38 AM
>>
>> Are you sure your sham-link is actually working? It doesn't sound like it
>> is. If the sham-link was up you would have intra-area O routes here.
>> Take a
>> look at "sh ip ospf neighbor". Do you see an adjacency over
>> the sham-link?
>>
>> On Tue, Mar 30, 2010 at 3:46 AM, Joe Astorino <jastorino_at_ipexpert.com>
>> wrote:
>>
>>
>>
>>
>>
>> Post your configurations
>>
>> On Tue, Mar 30, 2010 at 2:43 AM, Abiola Jewoola <biola_y2k_at_yahoo.com>
>> wrote:
>>
>>
>>
>>
>>
>>
>> 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
>> >> >
>> >> >
>> >> > Blogs and organic groups at http://www.ccie.net
>>
>>
>>
>>
>>
>>
>> >> >
>> >> >
>> >> > _______________________________________________________________________
>> >> > Subscription information may be found at:
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>>
>>
>>
>>
>>
>>
>> >> >
>> >> >
>> >> >
>> >> >
>> >> >
>> >>
>> >
>> >> >
>> >> >
>> >>
>> >>
>> >>
>> >> --
>> >> Regards,
>> >>
>> >>
>> >>
>> >> Joe Astorino - CCIE #24347
>> >> Sr. Technical Instructor - IPexpert
>>
>>
>>
>>
>>
>>
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>> >>
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>>
>>
>> >> _______________________________________________________________________
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>>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >
>> >
>>
>>
>> --
>> Regards,
>>
>>
>>
>> Joe Astorino - CCIE #24347
>> Sr. Technical Instructor - IPexpert
>>
>>
>>
>>
>>
>> Mailto: jastorino_at_ipexpert.com
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>> --
>> Regards,
>>
>>
>>
>> Joe Astorino - CCIE #24347
>> Sr. Technical Instructor - IPexpert
>> Mailto: jastorino_at_ipexpert.com
>>
>>
>>
>>
>>
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>> --
>> Regards,
>>
>>
>>
>> Joe Astorino - CCIE #24347
>> Sr. Technical Instructor - IPexpert
>> Mailto: jastorino_at_ipexpert.com
>>
>>
>>
>>
>>
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>> --
>> Regards,
>>
>>
>>
>> Joe Astorino - CCIE #24347
>> Sr. Technical Instructor - IPexpert
>> Mailto: jastorino_at_ipexpert.com
>>
>>
>>
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>> --
>> Regards,
>>
>>
>>
>> Joe Astorino - CCIE #24347
>> Sr. Technical Instructor - IPexpert
>> Mailto: jastorino_at_ipexpert.com
>>
>>
>> Telephone: +1.810.326.1444
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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
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>
>
>
> --
> Bryan Bartik
> CCIE #23707 (R&S, SP), CCNP
> Sr. Support Engineer - IPexpert, Inc.
> URL: http://www.IPexpert.com
>

-- 
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
eFax: +1.810.454.0130
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
Blogs and organic groups at http://www.ccie.net