Configuring OSPF on two directly connected routers which are in different areas

Question

I want to configure OSPF on the topology below. The problem is when I connect two routers to each other and when I config one router to area 0 and another one to area 1, they don't see each other as neighbors. So I cannot ping from one to another. I red Cisco docs and did some other labs and I know how to configure OSPF for different areas, but not this one. I got this error :

%OSPF-4-ERRRCV: Received invalid packet: mismatch area ID, from backbone area must be virtual-link but not found from 192.168.12.1, FastEthernet0/0

Can someone explain me why we should use different areas for two routers which their interfaces are directly connected? And what I should do to config?
Thank you all and Sorry for bad English.

And here is my configuration for there routers on this IOS c3640-jk9s-mz.124-16.image:

R1

version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Tarna
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
no ip icmp rate-limit unreachable
!
!
ip cef
no ip domain lookup
!
!
ip tcp synwait-time 5
!
!
interface FastEthernet0/0
 ip address 192.168.12.1 255.255.255.0
 duplex auto
 speed auto
!
!
router ospf 1
 log-adjacency-changes
 network 192.168.12.0 0.0.0.255 area 0
!
no ip http server
no ip http secure-server
!
no cdp log mismatch duplex
!
!
control-plane
!
line con 0
 exec-timeout 0 0
 privilege level 15
 logging synchronous
line aux 0
 exec-timeout 0 0
 privilege level 15
 logging synchronous
line vty 0 4
 login
!
!
end

R2

Current configuration : 1419 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Spielburg
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
no ip icmp rate-limit unreachable
!
!
ip cef
no ip domain lookup
!
!
ip tcp synwait-time 5
!
interface FastEthernet0/0
 ip address 192.168.12.2 255.255.255.0
 duplex auto
 speed auto
!
!
router ospf 1
 log-adjacency-changes
 network 192.168.12.0 0.0.0.255 area 1
!
no ip http server
no ip http secure-server
!
no cdp log mismatch duplex
!
control-plane
!
line con 0
 exec-timeout 0 0
 privilege level 15
 logging synchronous
line aux 0
 exec-timeout 0 0
 privilege level 15
 logging synchronous
line vty 0 4
 login
!
!
end

Answer 1

In order to connect two areas, one router has to serve as an area border router (ABR). That router has interfaces in both areas. In other words, the boundary between two areas is a router, not the link between two routers.

In your example, you could configure R1 so that interface f0/0 is in area 1, while the other interfaces are in area 0. That will make R1 the ABR for area 1.

Answer 2

To exchange routes in this topology you don't need two areas.

A two-router setup would be best configured in a single area. Best practice is to configure them both in area 0, but if it's going to remain a single-area design you can use whatever area number you like.

Try a configuration like this:

R1

router ospf 1
network 192.168.12.0 0.0.0.255 area 0

R2

router ospf 1
network 192.168.12.0 0.0.0.255 area 0

Answer 3

Area 0 is the backbone area and thus always required for communication between other areas. If you don't have 2 routers within the same area you won't have adjacency either. You should configure both routers with the same area so they have the same subnet configured. After that you can add other areas or other networks to area x. So your topology will not work.