Connecting backbone areas

[vpalania]

Hi,

1Consider I have configured a Virtual link to connect two backbone areas, in that case which area will be used as backbone later(because both are Area 0) .

Thanks,

Vijay

[Harold Ritter]

Both of these discontiguous area 0 linked to one another via a VL form one contiguous area 0.

Hope this helps,

[vpalania]

Hi,

Thanks for your quick response.

But I can't imagine how two areas are considered to be single area (Area 0).Consider an area wish to send LSA to area 0, then to which area it send.Could you please explain it with an example, since I have only gone through all these in thoeritically.

Thanks,

Vijay

[Harold Ritter]

When an LSA type 1 in a none-backbone area hits one ABR, this ABR converts it into a type an floods it to all routers in area 0, including the discontiguous portion of area 0. The VL is used to convey that information to the discontiguous portion of area 0.

Hope this helps,

[vpalania]

Hi,

Thanks for your response.

In your case, consider one area0 as A, and another area0 as B. Here, both A and B has the type 3 LSAs recevied from their respective non-backbone areas and those are also get transmitted over VL to other area 0.But in that case, the Tranist area between tham receives LSAs from both sides which also contains duplicates.Then, that is waste of bandwidth.If I am wrong, pls correct me.

Thanks,

Vijay

[Harold Ritter]

The LSA are indeed flooded via the VL through the transit area. I wouldn't call it a waste of bandwidth if you really need that VL.

Hope this helps,