From: yakout esmat (yesmat@xxxxxxxxxxxxxx)
Date: Mon Apr 22 2002 - 04:55:07 GMT-3
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
>
> ya
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