Hi Folks
Looking at topic subject line, most of us know that two OSPF speaking Router's have to match on below points to bring Neighborship.
1. The devices must be in the same area
2. The devices must have the same authentication configuration
3. The devices must be on the same subnet
4. The devices hello and dead intervals must match
5. The devices must have matching stub flags
Hmmm.. I agree with all above. But there is one observation i would like to share with you which i noticed while doing some Labs on GNS3.
I say Subnet should not be same.. Whaatttt ? No No Subnet should match. Indeed, my reaction was same. But it's true. friends, don't be taken away, iam not trying to prove that subnet should not match, its true that subnet should match. Now you must be thinking, what is this guy saying.. Please go through this and read last lines.
Let us discuss on this.
Please refer to below Topology. Router 1 is connected to Router 2 via Serial Link.
Please configure routers as given in Diagram. Look at the below configuration from my Topology.
Router - 1
-------------------------
R1#sh run int s1/0
Building configuration...
Current configuration : 107 bytes
!
interface Serial1/0
ip address 192.168.1.1 255.255.255.0
ip ospf 1 area 0
serial restart-delay 0
end
Router -2
-------------------------
R2#sh run int s1/0
Building configuration...
Current configuration : 106 bytes
!
interface Serial1/0
ip address 192.168.1.10 255.255.0.0
ip ospf 1 area 0
serial restart-delay 0
end
Now the time has come to check whether subnet should match to bring neighborship or not.
Neighbor Status on Router 1
----------------------------------
R1#sh ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
192.168.1.10 0 FULL/ - 00:00:36 192.168.1.10 Serial1/0
Looking at topic subject line, most of us know that two OSPF speaking Router's have to match on below points to bring Neighborship.
1. The devices must be in the same area
2. The devices must have the same authentication configuration
3. The devices must be on the same subnet
4. The devices hello and dead intervals must match
5. The devices must have matching stub flags
Hmmm.. I agree with all above. But there is one observation i would like to share with you which i noticed while doing some Labs on GNS3.
I say Subnet should not be same.. Whaatttt ? No No Subnet should match. Indeed, my reaction was same. But it's true. friends, don't be taken away, iam not trying to prove that subnet should not match, its true that subnet should match. Now you must be thinking, what is this guy saying.. Please go through this and read last lines.
Let us discuss on this.
Please refer to below Topology. Router 1 is connected to Router 2 via Serial Link.
Please configure routers as given in Diagram. Look at the below configuration from my Topology.
Router - 1
-------------------------
R1#sh run int s1/0
Building configuration...
Current configuration : 107 bytes
!
interface Serial1/0
ip address 192.168.1.1 255.255.255.0
ip ospf 1 area 0
serial restart-delay 0
end
Router -2
-------------------------
R2#sh run int s1/0
Building configuration...
Current configuration : 106 bytes
!
interface Serial1/0
ip address 192.168.1.10 255.255.0.0
ip ospf 1 area 0
serial restart-delay 0
end
Now the time has come to check whether subnet should match to bring neighborship or not.
Neighbor Status on Router 1
----------------------------------
R1#sh ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
192.168.1.10 0 FULL/ - 00:00:36 192.168.1.10 Serial1/0
