From: Carole Warner Reece (cwr@xxxxxxxxxxxxxx)
Date: Sat Sep 15 2001 - 11:00:02 GMT-3
Russell was interested in implementing a DDR link to backup another
link. Demand circuit behavior in the steady state (after the first few
minutes after a network route change) will send traffic only across the
main link (unless you ping the remote DDR address). While the main link is
active, the DDR interfaces would be up, running as demand circuits, and
they would be 'spoofing'.
When the main link goes down, this event will trigger LSAs, and the DDR
link will come up.
Carole
PS - Snapshot routing is for distance vector protocols, it exists to reduce
periodic update traffic.
http://www.cisco.com/warp/public/779/smbiz/service/knowledge/wan/snapshot.htm
------------------------------------------------------------------------
Carole Warner Reece, CCIE #5168
Mentor Technologies
http://www.mentortech.com
------------------------------------------------------------------------
At 09:09 AM 9/14/01 -0400, Olivier Martin wrote:
>Then what would prevent regular traffic from bringing up the ISDN link ?
>The costs associated with the interface ? And how about the snapshot
>routing ?
>
>Thanks for any info !
>
>Olivier
>
>-----Message d'origine-----
>De : Carole Warner Reece [mailto:cwr@mentortech.com]
>Envoyi : 14 septembre, 2001 09:05
>@ : Fear, Russell H; 'ccielab@groupstudy.com'
>Objet : Re: Help!
>
>
>Do you have 'ip ospf demand-circuit' on both sides of the link? If so, you
>should
>probably only use it one side.
>
>The ip ospf demand-circuit should only be configured on one router for a
>point-to-point circuit.
>
>If it is placed on one interface (say, not the ASBR), then a simple
>'dialer-list 1 protocol ip permit' allows the link to act as a backup
>circuit for OSPF area 0 (connecting an ASBR to area 0.)
>
>However, if 'ip ospf demand-circuit' is placed on both interfaces, then you
>can
>see the kind of behavior you are mentioning.
>
>Carole
>
>
>------------------------------------------------------------------------
>Carole Warner Reece, CCIE #5168
>Mentor Technologies
>http://www.mentortech.com
>------------------------------------------------------------------------
>At 10:38 AM 9/14/01 +0100, Fear, Russell H wrote:
> >Can anyone in the group help me with thhe following problem.
> >
> >I have an ospf router which is redistributing igrp into area 0. It also has
> >an isdn back-up as a demand circuit so that if the main connection to area
>0
> >dies, the isn kicks in and routes are still available. The problem is that
> >the LSAs caused by the re-distribution bring up the link continually. If I
> >block these, I block routing updates. I cant make the area a stub or an
>nssa
> >because it is area 0 and has two other areas hanging off it.
> >
> >Am I missing something obvious ? It's been driving me mad. Help please .
> >
> >Russell
> >
> >* 700 2201 Internal
> >* +44 ( 0 ) 870 238 2201 External
> >* russell.fear@capgemini.co.uk
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