OSPF routing with DMVPN

Unanswered Question
Dec 1st, 2009

I have a totally stubby area on one remote site router which I plan to integrate into a DMVPN network via DSL. Preferably, If my WAN link which is in Area 10 dies, the DMVPN tunnel act as a backup. Here's my problem, If I use backbone Area0 for the DMVPN tunnel, OSPF will prefer DMVPN instead of WAN during normal working conditions because the DMVPN link is in backbone Area0 which has preference over a non-zero area. If I use a non-zero, I come across the following problem:

My preference would be to use a new Area which is 55 but if I use it, I need to create a virtual-link for Area10-to-0. I think the virtual link is supported with a totally stubby area10 to a transit area55 and then to backbone area0. However, I hate to use virtual links. Is there a way around this?

If I use Area 10, any new DMPVN remote spoke sites will have to use the totally stubby Area 10 which I don't want


I have this problem too.
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Laurent Aubert Tue, 12/01/2009 - 20:27


Maybe I missed something, but if your DMVPN link belongs to area 0, it means your DMVPN spoke becomes an ABR so by playing with area default-cost command, you should be able to still prefer the ABR connected to your WAN link over the DMVPN one..

Your router inside the area 10 will have the choice between two default routes with two different metrics.




aamercado Tue, 12/01/2009 - 22:31

Ok, I'll try "area 10 default-cost 1000" on the R-SMA router but not sure if it would work. My next window is in 12 hours to do this but I thought if Tunnel0 (10.55.1.X) is part of Area0, then the R-SMA will act as a ABR and since R-SMA's Tu0 is in Area0, it will populate full routing table and not a default route.

Originally, I had tried a "ip ospf cost" on Tu0 but that didn't work for me...hopefully this "area 10 default-cost" will work.


Laurent Aubert Wed, 12/02/2009 - 09:09

You need to configure your R-SMA just like the other ABR: area 10 stub no-summary to filter any external and inter-area routes.


aamercado Wed, 12/02/2009 - 14:30

nope doesn't work on R-SMA

router ospf 1
area 10 stub
network area 10
network area 0

If I put in the following 2 configs, I still get full ospf routes on tunnel when I want to get it from the physical interface off the WAN

area 10 default-cost 1000
area 10 stub no-summary

Laurent Aubert Wed, 12/02/2009 - 14:45

I just realized you actually want the R-SMA itself to use its intra-area route over the WAN. I first thought you were talking about other routers belonging to the area 10.

Sorry for the confusion.

You can't change the OSPF route selection order which is intra-area > inter-area > external.

You should run another routing protocol in your DMVPN cloud so you could use the AD as the tie-breaker.



Anupam Datta Tue, 12/08/2009 - 03:32

Hi !,

Laurent is right , you cannot change OSPF route selection order. So if two OSPF neighbor  is established and one of them is in Intra-Area , then that will be the best route. But if you want to use the Tunnel as Backup route only. Then you can controll th route towards the destination of tunnels, so that tunnels will not built up untill or unless primary link goes down. As other informations like tunnel type or configurations not available , so I can't say the

details of such configs. You can try this or if post the details could be helpfull.




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