OSPF area design

[Yachay]

Hi!

I need your help in order to know if the design which I am attaching will work or I will have some problems with that.

Thanks!

[Reza Sharifi]

Hi,

It should work fine You have router-C connecting router-A and B in area 1 and the link between A and B is in area 0.

HTH

[Joseph W. Doherty]

Depends on how you configure your areas.

For example, if you summarize area 1.1.1.1, and RtrB loses its p2p to RtrC, it would drop area 1.1.1.1 traffic unless you also have another area 1.1.1.1 link on it. If there were another area 1.1.1.1 link, to say a RtrD, traffic might need to flow down to RtrD, then back to RtrA to get to RtrC.

[Julio E. Moisa]

Hi

It will work, additional to other members comments is configure Router C's interfaces connecting to Router A and B into the area 0 and keep the networks behind of Router C into of Area 1. 

Now if your network is built with 3 routers only, multiareas is not needed, usually multiareas is used with 10 or more routers. 

Hope it is useful

:-)

[Yachay]

Thanks all!

Actually, the network has more routers (6 in area 0) and several other ones in different areas connected to those routers A or B (ABRs) through single links, but a particular location has two links to routers A and B.

[Julio E. Moisa]

Hi

Thank you for the explanation, you could keep just the links to router A and B over the Area 0 and the other networks behind the router over area X. So these router connected Router A & B (saying backbone) will be an ABR.

[Yachay]

Thanks Julio.

That was my first thought, but architects want to keep only those couple of routers as the main and only ABRs in the whole network. Just I wanted to be sure that configuring the same area in different ABRs won't break anything.

Thanks again.

[Reza Sharifi]

For 3 routers, you really don't need 2 areas and much simpler with one area (area0) but if it is a requirement than that is fine too.

HTH

[Julio E. Moisa]

Hi

It will work fine, and no inconveniences will be generated, other routes will be seen as IA (inter areas), If you are going to use different areas I suggest include this commando on your OSPF process: ISPF, Incremental SPF allows the system to recompute only the affected part of the tree.

Hope it is useful

:-)