[c-nsp] Network Design - OSPF Convergence Issue

[Bruce Pinsky]

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Shakeel Ahmad wrote:
> Guys,
> 
> we came across a live scenario here and i am not a big OSPF guru...please
> guide me here
> 
>                 +               ++ HQ ++
>                 |
>                 |       --         P1
>                 |       |       / / | \ \
>                 |       OSPF
>                 |       |       \ \ | / /
>                 |       --      1 2 3 4 5
>                 |
>                 +                ++Core++
> 
> 
> Client is running simple GRE tunnels via 5 different providers (1,2,3,4,5)
> to their headquarter's ISP (P1)...   All providers are connected on
> different boundry routers  and HQ on a single router..
> 
> Now Loopback IP's are advertised via OSPF (single area) for all boundry
> routers of client and HQ....Issue currently faced is: loopback IP's are
> learnt from all GRE tunnels...while changing Costs on different GRE tunnels
> doesn't change the traffic path and CORE learns the path from (low cost GRE
> tunnel boundry router)..while BGP ssession is being used for distributing
> ....
> 
> The basic need is to converge the network in between boundry routers ON
> DEMAND and sometimes on incident based events.
> 
> Can someone share..what would be the best design...covering ON DEMAND path
> selection via OSPF in this design.
> 
> (i guess i confused many things..let me have your questions)
> 

Maybe I'm missing something, but if each of the boundary routers has a
tunnel to HQ, how is the HQ router learning all the loopbacks over all the
tunnel interfaces?   That would seem to imply that all the boundary routers
are sharing a common subnet somehow or that they are fully-meshed.  Is that
the case?  Seems like we need to know more about the topology in this case
cause something doesn't seem right.

- --
=========
bep

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