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New Member

OSPF problem: Neighbor Down 1-2 times per day

Hi

We have 4 devices are running OSPF (3 cisco routers and 1 Juniper firewall as show in attachment file). In last few months, we got Neighbot Down message almost 1-2 times per day. Network between them interrupt for a short time and even monitoring mechanism does not aware the interruption(down time is too short). Could I have your advice of any possible root cause to this problem?


Timer intervals configured to all devices are same: Hello 10, Dead 40, Wait 40, Retransmit 5

------------------------------------------------------------------------------------------------------------

Neighbor A

Neighbor A#sh ip ospf neighbor 

Neighbor ID     Pri   State           Dead Time   Address         Interface
172.16.255.128    1   FULL/DROTHER    00:00:34    172.16.108.11   GigabitEthernet0/11
172.16.255.130    1   FULL/DR         00:00:33    172.16.108.2    GigabitEthernet0/11
172.16.255.64     1   FULL/DROTHER    00:00:34    172.16.107.1    GigabitEthernet0/12
172.16.255.128    1   FULL/DROTHER    00:00:38    172.16.107.11   GigabitEthernet0/12
172.16.255.130    1   FULL/DR         00:00:38    172.16.107.7    GigabitEthernet0/12

Neighbor A#show log

Mar 16 06:03:33.159: %OSPF-5-ADJCHG: Process 1, Nbr 172.16.255.128 on GigabitEthernet0/12 from FULL to DOWN, Neighbor Down: Dead timer expired
Mar 16 06:03:50.137: %OSPF-5-ADJCHG: Process 1, Nbr 172.16.255.128 on GigabitEthernet0/12 from LOADING to FULL, Loading Done
Mar 16 21:15:05.509: %OSPF-5-ADJCHG: Process 1, Nbr 172.16.255.64 on GigabitEthernet0/12 from LOADING to FULL, Loading Done

------------------------------------------------------------------------------------------------------------

Neighbor B

Neighbor B#sh ip ospf neighbor 

Neighbor ID     Pri   State           Dead Time   Address         Interface
172.16.255.128    1   FULL/DROTHER    00:00:36    172.16.108.11   GigabitEthernet0/11
172.16.255.129    1   FULL/BDR        00:00:35    172.16.108.1    GigabitEthernet0/11
172.16.255.64     1   FULL/DROTHER    00:00:39    172.16.107.1    GigabitEthernet0/12
172.16.255.128    1   FULL/DROTHER    00:00:30    172.16.107.11   GigabitEthernet0/12
172.16.255.129    1   FULL/BDR        00:00:35    172.16.107.6    GigabitEthernet0/12

Neighbor B#show log

Mar 16 06:03:33.143: %OSPF-5-ADJCHG: Process 1, Nbr 172.16.255.128 on GigabitEthernet0/12 from FULL to DOWN, Neighbor Down: Dead timer expired
Mar 16 06:03:50.122: %OSPF-5-ADJCHG: Process 1, Nbr 172.16.255.128 on GigabitEthernet0/12 from LOADING to FULL, Loading Done
Mar 16 21:14:58.054: %OSPF-5-ADJCHG: Process 1, Nbr 172.16.255.64 on GigabitEthernet0/12 from LOADING to FULL, Loading Done
Mar 16 21:15:03.800: %OSPF-5-ADJCHG: Process 1, Nbr 172.16.255.128 on GigabitEthernet0/12 from LOADING to FULL, Loading Done

------------------------------------------------------------------------------------------------------------

Neighbor C

Neighbor C#sh ip ospf neighbor 

Neighbor ID     Pri   State           Dead Time   Address         Interface
172.16.255.129    1   FULL/BDR        00:00:35    172.16.108.1    FastEthernet0/1/0
172.16.255.130    1   FULL/DR         00:00:38    172.16.108.2    FastEthernet0/1/0
172.16.255.64     1   2WAY/DROTHER    00:00:30    172.16.107.1    FastEthernet0/0/1
172.16.255.129    1   FULL/BDR        00:00:35    172.16.107.6    FastEthernet0/0/1
172.16.255.130    1   FULL/DR         00:00:33    172.16.107.7    FastEthernet0/0/1

Neighbor C#show log

Mar 16 06:03:23.571: %OSPF-5-ADJCHG: Process 1, Nbr 172.16.255.130 on FastEthernet0/0/1 from FULL to DOWN, Neighbor Down: Dead timer expired
Mar 16 06:03:25.479: %OSPF-5-ADJCHG: Process 1, Nbr 172.16.255.129 on FastEthernet0/0/1 from FULL to DOWN, Neighbor Down: Dead timer expired
Mar 16 06:03:29.415: %OSPF-5-ADJCHG: Process 1, Nbr 172.16.255.64 on FastEthernet0/0/1 from EXSTART to DOWN, Neighbor Down: Dead timer expired
Mar 16 06:03:50.112: %OSPF-5-ADJCHG: Process 1, Nbr 172.16.255.129 on FastEthernet0/0/1 from LOADING to FULL, Loading Done
Mar 16 06:03:50.112: %OSPF-5-ADJCHG: Process 1, Nbr 172.16.255.130 on FastEthernet0/0/1 from LOADING to FULL, Loading Done
Mar 16 21:14:53.740: %OSPF-5-ADJCHG: Process 1, Nbr 172.16.255.130 on FastEthernet0/0/1 from FULL to DOWN, Neighbor Down: Dead timer expired
Mar 16 21:15:03.793: %OSPF-5-ADJCHG: Process 1, Nbr 172.16.255.130 on FastEthernet0/0/1 from LOADING to FULL, Loading Done

 

 

  • LAN Switching and Routing
9 REPLIES
New Member

How's the cpu utilization on

How's the cpu utilization on these routers during the flap?

New Member

We were not monitor CPU

We were not monitor CPU utilization of these routers and I just put them in monitoring. The flap often happens in one minute and I am not sure if it will be monitored. I will provide monitor results after next flap.

How did u configure the

How did u configure the switch between Router C and Firewall D, since you are forming  all the neighbors on F0/0/1 which is between Router C and Firewall

Regards Thanveer "Everybody is genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is a stupid."
New Member

On the switch between C and D

On the switch between C and D, 3 ports (to C, to D and to A,B switch) were assigned with same vlan.

Following interfaces are all configured in subnet 172.16.107.0/24:

  • G0/12 on Router A
  • G0/12 on Router B
  • F0/0/1 on router C
  • Outside (to switch) on Firewall D
New Member

We have interupt this morning

We have interupt this morning and CPU utilization of these routers are quite low.

CPU utilization:

Router A: 5%             Router B: 5%        Router C: 2%

show log:

Router A

Mar 20 01:40:17.252: %OSPF-5-ADJCHG: Process 1, Nbr 172.16.255.128 on GigabitEthernet0/12 from LOADING to FULL, Loading Done
Mar 20 01:40:26.203: %OSPF-5-ADJCHG: Process 1, Nbr 172.16.255.64 on GigabitEthernet0/12 from LOADING to FULL, Loading Done

Router B

Mar 20 01:40:24.597: %OSPF-5-ADJCHG: Process 1, Nbr 172.16.255.128 on GigabitEthernet0/12 from LOADING to FULL, Loading Done

Router C

Mar 20 01:40:16.163: %OSPF-5-ADJCHG: Process 1, Nbr 172.16.255.129 on FastEthernet0/0/1 from FULL to DOWN, Neighbor Down: Dead timer expired
Mar 20 01:40:16.179: %OSPF-5-ADJCHG: Process 1, Nbr 172.16.255.64 on FastEthernet0/0/1 from LOADING to FULL, Loading Done
Mar 20 01:40:17.243: %OSPF-5-ADJCHG: Process 1, Nbr 172.16.255.129 on FastEthernet0/0/1 from LOADING to FULL, Loading Done
Mar 20 01:40:24.559: %OSPF-5-ADJCHG: Process 1, Nbr 172.16.255.130 on FastEthernet0/0/1 from FULL to DOWN, Neighbor Down: Dead timer expired
Mar 20 01:40:24.591: %OSPF-5-ADJCHG: Process 1, Nbr 172.16.255.130 on FastEthernet0/0/1 from LOADING to FULL, Loading Done

 

I am thinking to replace a switch between C and D, any advice? Thanks. 

New Member

 Hiis there any L2 loops

 

Hi

is there any L2 loops happening in network..

New Member

I think no L2 loops in the

I think no L2 loops in the network. We have spanning tree configured on switches connecting to router A & B.

 

VLAN0108
  Spanning tree enabled protocol ieee
  Root ID    Priority    32876
             Address     5c50.15a3.8480
             This bridge is the root
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    32876  (priority 32768 sys-id-ext 108)
             Address     5c50.15a3.8480
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  300 sec

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi1/0/45            Desg FWD 4         128.45   P2p Edge
Gi1/0/47            Desg FWD 19        128.47   P2p Edge
Gi1/0/48            Desg FWD 4         128.48   P2p Edge
 
 
 
 
VLAN0107
  Spanning tree enabled protocol ieee
  Root ID    Priority    32875
             Address     5c50.15ec.f000
             This bridge is the root
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    32875  (priority 32768 sys-id-ext 107)
             Address     5c50.15ec.f000
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  300 sec

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi1/0/45            Desg FWD 4         128.45   P2p Edge
Gi1/0/47            Desg FWD 19        128.47   P2p Edge
Gi1/0/48            Desg FWD 4         128.48   P2p Edge
New Member

It looks like the adjacency

It looks like the adjacency on multiple interfaces are flapping.  Are all these routers connected through a common switch?

New Member

Please refer to topology as

Please refer to topology as attach file I just updated. Actually we have 3 offices (site 1, 2 and 3) are connecting with 10M FTTB link between 2 sites.

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