hi,
Although advertising router is 192.168.234.3, how can R1 learn 4.4.4.4 from both of the R2 and R3? Why does not it learn only from R3?
R1#show ip route ospf | begin 4.4.4.4
O E2 4.4.4.4 [110/20] via 192.168.13.3, 00:38:49, FastEthernet0/1
[110/20] via 192.168.12.2, 00:38:49, FastEthernet0/0
R1#show ip ospf database external
OSPF Router with ID (192.168.13.1) (Process ID 1)
Type-5 AS External Link States
Routing Bit Set on this LSA in topology Base with MTID 0
LS age: 1346
Options: (No TOS-capability, DC)
LS Type: AS External Link
Link State ID: 4.4.4.4 (External Network Number )
Advertising Router: 192.168.234.3
LS Seq Number: 80000001
Checksum: 0xFAE5
Length: 36
Network Mask: /32
Metric Type: 2 (Larger than any link state path)
MTID: 0
Metric: 20
Forward Address: 192.168.234.4
External Route Tag: 0
regards,