I am designing a new OSPF network that will combine several sites. My original plan involved adding all the WAN routers into Area 0 and then either putting each (L3) user switch and each data centre into its own area or creating an Area for each site.
The problem is now that we are looking into also interconnecting our L2 domains in the Datacenters, this breaks my idea.
Has anybody seen a best practice document or design guide that took this into account? Does it make sense to put all datacentres in one big area for this?