Configuring OSPF Static Neighbors in Cisco
Pre-requisites : Open shortest path first (OSPF) router roles and configuration, OSPF network types
OSPF Static Neighbors :
- In an OSPF autonomous system, when OSPF network type is configured either to be
- Non-broadcast (NBMA)
- Point-to-multipoint non-broadcast you must configure static neighbors to ensure that the OSPF can form neighbor relationship.
- To configure OSPF static neighbor(s), you have to manually specify the neighbor routers’ IP address as a subcommand under the router ospf <process> command.
OSPF Static Neighbors command:
Router OSPF subcommand |
Description |
Example |
---|---|---|
neighbor <ip-address> [cost number] | To Specify a neighbor and assign a cost to the neighbor. (cost parameter is optional in this command) | Router(config-router)# neighbor 192.168.1.4 cost 180 |
OSPF network type commands:
Interface configuration subcommand |
Description |
---|---|
ip ospf <network broadcast | non-broadcast | point-to-multipoint | point-to-point> | Configures an interface OSPF network type to broadcast/non-broadcast/point-to-point/point-to-multipoint (point-to-multipoint -Configures an interface as point-to-multipoint for broadcast media.) |
no ip ospf network | To revert the OSPF network type back to its default configuration. |
Configuring OSPF Static Neighbors:
Step 1: Create the physical topology in GNS3 as show in the image below :
Step 2: Configure IPv4 address on the physical interface of the routers :
R1(config)#interface FastEthernet0/0 R1(config-if)#ip address 10.1.1.1 255.255.255.0 R1(config-if)#no shutdown R1(config-if)#interface Serial1/0 R1(config-if)#ip address 192.168.1.1 255.255.255.0 R1(config-if)#no shutdown
R2(config)#interface FastEthernet0/0 R2(config-if)#ip address 10.1.1.2 255.255.255.0 R2(config-if)#no shutdown
R3(config-if)#interface Serial1/0 R3(config-if)#ip address 192.168.1.2 255.255.255.0 R3(config-if)#no shutdown
Step 3: Configuring OSPF process on all the routers with the command router ospf <process-id> :
R1(config)#router ospf 1 R1(config-router)#exit
R2(config)#router ospf 1 R2(config-router)#exit
R3(config)#router ospf 1 R3(config-router)#exit
Step 4: Enabling OSPF on the interfaces with the interface level sub-command ip ospf <process-id> area <area-id> :
R1(config)#interface FastEthernet0/0 R1(config-if)#ip ospf 1 area 0 R1(config-if)#interface Serial1/0 R1(config-if)#ip ospf 1 area 0
R2(config)#interface FastEthernet0/0 R2(config-if)#ip ospf 1 area 0
R3(config-if)#interface Serial1/0 R3(config-if)#ip ospf 1 area 0
Step 5: Checking the IPv4 routing table on the routers and seeing OSPF route entry :
R1#show ip route
R2#show ip route
R3#show ip route
Step 6: Checking OSPF neighbor relationships with the show command, show ip ospf neighbor :
R1#show ip ospf neighbor
R2#show ip ospf neighbor
R3#show ip ospf neighbor
Step 7: Configuring OSPF network type on serial interface of R1 and R3 :
R1(config)#interface serial1/0 R1(config-if)#ip ospf network non-broadcast
R3(config)#interface serial1/0 R3(config-if)#ip ospf network non-broadcast
Step 8: Checking OSPF neighbors relationships on R1 and R3 :
R1#show ip ospf neighbor
- OPSF neighbor relationship with R3 using neighbor-id 192.168.1.2 is removed.
R3#show ip ospf neighbor
- No OSPF neighbor relationship.
Step 9: Configuring OSPF static neighbor on R1 pointing to R3 and vice versa :
R1(config)#router ospf 1 R1(config-router)#neighbor 192.168.1.2
R3(config-if)#router ospf 1 R3(config-router)#neighbor 192.168.1.1
Step 10: Verify the OSPF neighbor relationships formed using the show ip ospf neighbor command :
R1#show ip ospf neighbor
- OPSF neighbor relationship with R2 and R3 using neighbor-id 10.1.1.2 & 192.168.1.2 respectively.
R2#show ip ospf neighbor
- OPSF neighbor relationship with R2 using neighbor-id 192.168.1.1.
R3#show ip ospf neighbor
- OPSF neighbor relationship with R1 using neighbor-id 192.168.1.1.
Step 11: Verifying connectivity throughout the topology :
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