From: Ashot Hakobyan (ashot.hakobyan@xxxxxxxxxxxxxxxxx)
Date: Tue Apr 23 2002 - 16:14:28 GMT-3
Yakout,
I would suggest:
ip route 0.0.0.0 0.0.0.0 bri 0
router ospf 100
default-information originate
This way, the default route will be in the routing table only when the bri 0
is up, and ospf will originate the default route only when it is in the
routing table.
Ashot
> -----Original Message-----
> From: yakout esmat [mailto:yesmat@iprimus.com.au]
> Sent: Monday, April 22, 2002 5:55 PM
> To: Bob Sinclair
> Cc: ccielab@groupstudy.com
> Subject: RE: OSPF Conditional Default Origination
>
>
> Bob,
>
> I actually have taken Halabi's example in Chapter 12 and
> tried to build my scenario based on that.
>
> But again, my route-map can only check for the existance of
> the route but can't check for the absence of it.
>
> What I am trying to acheive exactely is: advertise the
> default route, when my frame relay interface (physical) goes
> down and my ISDN (Backup)comes up. When this happens the
> router that is the source of the default route looses some
> routes because of the F/R interface lose, and has to inject
> the default into OSPF Domain in order for my network to be
> able still to reach every interface.
>
> But, when F/R interface is up and ISDN down(Standby mode)no
> default should be injected into OSPF Domian.
>
> Your idea, using Admin distance to control the existance of a
> specific route when my original route disappears is an
> excellent one (never thought about
> it) but the question still remains whether that would be
> acceptable in the lab exam??
>
> Thanks for your feedback, any other ideas are very much appreciated.
>
> Ya
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On
> Behalf Of Bob Sinclair
> Sent: Monday, April 22, 2002 1:35 AM
> To: yakout esmat
> Cc: ccielab@groupstudy.com
> Subject: Re: OSPF Conditional Default Origination
>
>
> Yakout,
>
> BGP has the "non-exist" map syntax for the purpose you are
> trying to achieve. The fact that it has this special syntax
> makes me think you will need to test for the existence, not
> absence, of a route in OSPF.
>
> The best example of this is in Halabi's book. Can you
> arrange to advertise the default only if some other route is
> present, then arrange if this other route is present, then
> 148.5.5.0 must not be? Perhaps through metric or AD?
>
> I think you are correct in your understanding of the command.
> Cannot test absence of route, only presence. Make
> appearance of route A conditional on absence of 148.5.5.0,
> then advertise default only if A is present. If A is
> present, 148.5.5.0 must not be.
>
> -Bob
>
>
> . ----- Original Message -----
> From: "yakout esmat" <yesmat@iprimus.com.au>
> To: "Groupstudy" <ccielab@groupstudy.com>
> Sent: Sunday, April 21, 2002 6:43 AM
> Subject: OSPF Conditional Default Origination
>
>
> > Hi all,
> >
> > I have a problem configuring OSPF Conditional Default
> Origination, my
> config
> > as follows:
> >
> > !
> > router ospf 100
> > summary-address 198.168.0.0 255.255.0.0
> > network 148.5.6.6 0.0.0.0 area 0
> > network 148.5.16.6 0.0.0.0 area 0
> > default-information originate route-map default
> > !
> > route-map default deny 10
> > match ip address 3
> > !
> > route-map default permit 20
> > !
> > access-list 3 permit 148.5.5.0 0.0.0.255
> > !
> > end
> >
> > What I want to achieve is: If network 148.5.5.0/24 exists in the
> > routing table DO NOT advertise the default route into OSPF Domain
> > (which is represented by first instance of the route-map 10)
> >
> > Otherwise Advertise the default (which is covered by the second
> > instance
> 20)
> >
> > My observation is: it only works if the first instance permits the
> > default based on the EXISTANCE of the network in the table,
> and denies
> > the default if the network doesn't exist in the table.
> >
> > Do I have misunderstanding of the Conditional Default Origination or
> what??
> >
> > Any feed back is very much appreciated.
> >
> > Thanks in advance
> >
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