OSPF Graceful Shutdown

Similar to using the shutdown command on an interface, there is also a shutdown command for OSPF. This allows you to gracefully stop the OSPF routing process without removing the configuration from your router. You can do this globally or on the interface level.

If you want to do a graceful shutdown globally, you have to use the shutdown command under the OSPF process. This will:

• Drop all neighbor adjacencies
• Flush all LSAs that the router originated by setting the age to 3600 seconds
• Send hello packets with the DR/BDR set to 0.0.0.0 and an empty neighbor list. This will trigger other OSPF routers to fall back to init state.
• Stop sending/receiving OSPF packets.

If you shut OSPF on the interface level with the ip ospf shutdown command, it will do this:

• Drop all neighbor adjacencies on the interface you selected.
• Flood updated LSAs where all information (prefix, neighbors) from the selected interface is removed.
• Send hello packets with the DR/BDR set to 0.0.0.0 and an empty neighbor list. This will trigger other OSPF router to fall back to init state.
• Stop sending/receiving OSPF packets.

Configuration

Let’s look at this in action. I will use these two routers that are running OSPF:

Right now, these two routers are OSPF neighbors:

R1#show ip ospf neighbor 

Neighbor ID     Pri   State           Dead Time   Address         Interface
192.168.12.2      1   FULL/BDR        00:00:39    192.168.12.2    GigabitEthernet0/1

Let’s shut the OSPF process on R1:

R1(config)#router ospf 1
R1(config-router)#shutdown

OSPF is no longer running so the neighbor adjacency will drop:

R1#
%OSPF-5-ADJCHG: Process 1, Nbr 192.168.12.2 on GigabitEthernet0/1 from FULL to DOWN, Neighbor Down: Interface down or detached

R1#show ip ospf neighbor

If you look at the interface level, you will still see some OSPF details:

R1#show ip ospf interface GigabitEthernet 0/1
GigabitEthernet0/1 is up, line protocol is up 
  Internet Address 192.168.12.1/24, Area 0, Attached via Network Statement
  Process ID 1, Router ID 192.168.13.1, Network Type BROADCAST, Cost: 1
  Topology-MTID    Cost    Disabled    Shutdown      Topology Name
        0           1         no          no            Base
  Transmit Delay is 1 sec, State DOWN, Priority 1
  No designated router on this network
  No backup designated router on this network
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    oob-resync timeout 40

As expected, our configuration is still in the running config:

R1#show running-config | begin ospf
router ospf 1
 shutdown
 network 192.168.12.0 0.0.0.255 area 0

That’s all there is to it.

hostname R1
!
ip cef
!
interface GigabitEthernet0/1
 ip address 192.168.12.1 255.255.255.0
!
router ospf 1
 shutdown
 network 192.168.12.0 0.0.0.255 area 0
!
end

hostname R2
!
ip cef
!
interface GigabitEthernet0/1
 ip address 192.168.12.2 255.255.255.0
!
router ospf 1
 network 192.168.12.0 0.0.0.255 area 0
!
end