Re: OSPF SHAM-LINK

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
>
>
>
>
>
>
> >> >
> >> >
> _______________________________________________________________________
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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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>
>
>
> Joe Astorino - CCIE #24347
> Sr. Technical Instructor - IPexpert
>
>
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>
>
> Joe Astorino - CCIE #24347
> Sr. Technical Instructor - IPexpert
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> Joe Astorino - CCIE #24347
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> Joe Astorino - CCIE #24347
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