Re: 3 OSPF non-zero areas

You may number your areas anything you want... But if you want them to
talk to each other, Area 0 MUST exist. In order to create a virtual
link (and have it work), Area 0 MUST previously exist.

Interestingly, you can bring a loopback in, create your VL's and then
REMOVE the loopback, and things will continue to work just fine. At
least up until the process/router resets. :)

Area 0 is used to move LSAs. Gotta have it if you want them moved!

Tunnels? Sure. As long as there's an area 0!

*Scott Morris*, CCIE/x4/ (R&S/ISP-Dial/Security/Service Provider) #4713,

JNCIE-M #153, JNCIS-ER, CISSP, et al.

JNCI-M, JNCI-ER

smorris_at_internetworkexpert.com

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Anantha Subramanian Natarajan wrote:
> Hi All,
>
> Is it possible to run OSPF when there are three OSPF areas as shown below
> and none of them is not a area 0.
>
> R1 --ospf area3 --R2 ---ospf area4 ---R3 ----ospf area5 --R4
>
> My understanding is that, virtual-link would be only useful when to join a
> non-zero area to connect to area0 which is seperated by another
> non-zero area.Also the virtual links would be useful in case where area 0 is
> broken in between a non-zero area.Assuming my above understanding is right,I
> am thinking the above scenario will not be able to use virtual links to
> propagate OSPF routes among R1,R2,R3,R4.
>
> In this case,if I would be able to build GRE tunnel between
> R1-R2,R2-R3,R3-R4 and run OSPF on area0 over them,In that case,will the OSPF
> routes would be able to get propagated ?
>
> Thanks for the help
>
> Regards
> Anantha Subramanian Natarajan
>
>
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Received on Wed May 06 2009 - 01:27:22 ART