Why the OSPF router do not have neighbor?

Question

I have two Routers in the Cisco Packet Tracer:

Router2-1, Router2-2, Router2-3 all have their own loopback 0 with IP address 1.1.1.1, 2.2.2.2, 3.3.3.3.

I only launched the OSPF progress in the Router2-1's Gig0/0/0 port and annunciated .

There is in the running-config:

......
!
router ospf 1
 log-adjacency-changes
 network 0.0.0.0 0.0.0.0 area 0
!
......

there is no neighbor in the Router2-1:

Router#show ip ospf neighbor 

Router#

In logically speaking, there should have a neighbor of Router2-2, why there is none.

---

EDIT-01

But, however, after I launched the OSPF 1 in the Router2-2's Gig0/0/0, the Router2-1 still can not find the OSPF neighbor.

Router#show ip ospf neighbor 

Router#

and, in the Router2-2's running-configuration:

...
router ospf 1
 log-adjacency-changes
 network 0.0.0.0 0.0.0.0 area 0
!
...

how can I know which interface launched the ospf 1?

the Router2-1 ospf database:

Router#show ip ospf database 
            OSPF Router with ID (1.1.1.1) (Process ID 1)

                Router Link States (Area 0)

Link ID         ADV Router      Age         Seq#       Checksum Link count
1.1.1.1         1.1.1.1         34          0x80000001 0x00510c 0

the Router2-2 ospf database:

Router#show ip ospf database 
            OSPF Router with ID (2.2.2.2) (Process ID 1)

                Router Link States (Area 0)

Link ID         ADV Router      Age         Seq#       Checksum Link count
2.2.2.2         2.2.2.2         325         0x80000001 0x000550 0

but each other show the ospf neighbor all get empty result.

Router#show ip ospf neighbor 

Router#

---

EDIT-02

In my Router2-2, the interface:

Router>show ip interface brief 
Interface              IP-Address      OK? Method Status                Protocol 
GigabitEthernet0/0/0   192.168.1.1     YES manual up                    up 
GigabitEthernet0/0/1   192.168.2.1     YES manual up                    up 
Loopback0              2.2.2.2         YES manual up                    up 
Vlan1                  unassigned      YES unset  administratively down down

Answer 1

If you have IP addresses configured correctly on router's interfaces, you should be good to go. But! Change your network configuration in OSPF section to this:

router ospf 1
 network 0.0.0.0 255.255.255.255 area 0

OSPF network statement uses wildcard, not netmask.

[EDIT]

As mentioned by Ron Maupin, real devices are able to detect user intention and build neighbor relation even with network 0.0.0.0 0.0.0.0 area 0.

Proof:

interface Loopback0
 ip address 1.1.1.1 255.255.255.255
!
interface FastEthernet0/0
 ip address 10.1.1.1 255.255.255.0
 duplex full
!
router ospf 1
 network 0.0.0.0 255.255.255.255 area 0


R1#sh ip ospf neighbor

Neighbor ID     Pri   State           Dead Time   Address         Interface
2.2.2.2           1   FULL/DR         00:00:26    10.1.1.2        FastEthernet0/0


R1#sh ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
       + - replicated route, % - next hop override

Gateway of last resort is not set

      1.0.0.0/32 is subnetted, 1 subnets
C        1.1.1.1 is directly connected, Loopback0
      2.0.0.0/32 is subnetted, 1 subnets
O        2.2.2.2 [110/2] via 10.1.1.2, 00:14:28, FastEthernet0/0
      10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C        10.1.1.0/24 is directly connected, FastEthernet0/0
L        10.1.1.1/32 is directly connected, FastEthernet0/0

PacketTracer unable to recognize the situation :

R2#sh ip ospf neighbor 

R2#

Answer 2

OSPF is a routing protocol, ie. it is used by routers participating in OSPF to exchange their routes and link states. If there's only one router configured to use OSPF in a network there are no neighbors.

Answer 3

network 0.0.0.0 255.255.255.255 area 0