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OSPF Neighbors Between a Third-Party Device and NE40E Became Up and Down Frequently

Publication Date:  2013-10-23 Views:  25 Downloads:  0
Issue Description

Networking:

     |g8/2/1.2----ospf area0-----g8/2.2 |
NE40E|                                            |C7609
     |g8/2/1.43---ospf area43--g8/2.43|

C7609 router id: 11.87.208.222   NE40E router id: 11.87.208.221

Symptom:

The OSPF neighbor of interface g8/2/1.2 on the NE40E became up and down frequently but the OSPF neighbor of interface g8/2/1.43 was normal.

NE40E log:
Apr 27 2010 03:47:19 Pnxyncs02 %%01OSPF/6/NSSA_INTRVL_DELETE(l)[174808]:
The timer of the NSSA translator is deleted. (ProcessId=101, AreaId=0.0.0.43)
Apr 27 2010 03:47:19 Pnxyncs02 %%01OSPF/6/NSSA_FLUSHING_STRTD(l)[174809]:Translated Type-5 LSA flushing started. (ProcessId=101, AreaId=0.0.0.43)
Apr 27 2010 03:47:19 Pnxyncs02 %%01OSPF/6/NSSA_FLUSHING_END(l)[174810]:Translated Type-5 LSA flushing end. (ProcessId=101, AreaId=0.0.0.43)
Apr 27 2010 03:49:24 Pnxyncs02 %%01OSPF/6/NBR_DOWN_REASON(l)[174811]:Neighbor state leaves full or changed to Down. (ProcessId=101, NeighborRouterId=11.87.208.222, NeighborAreaId=0, NeighborInterface=GigabitEthernet8/2/1.2,NeighborDownImmediate reason=Neighbor Down Due to 1-Wayhello Received, NeighborDownPrimeReason=1-Wayhello Received, NeighborChangeTime=[2010/04/27] 03:49:24)
Apr 27 2010 03:49:24 Pnxyncs02 %%01OSPF/6/DFT_LSA_FLUSH(l)[174812]:Re-advertise default LSA. (ProcessId=101, LsaType=3, AdvertisingRouter=11.87.208.221)
Apr 27 2010 03:49:24 Pnxyncs02 %%01OSPF/6/DFT_LSA_FLUSH(l)[174813]:Re-advertise default LSA. (ProcessId=101, LsaType=3, AdvertisingRouter=11.87.208.221)
Apr 27 2010 03:49:24 Pnxyncs02 %%01OSPF/6/DFT_LSA_FLUSH(l)[174814]:Re-advertise default LSA. (ProcessId=101, LsaType=3, AdvertisingRouter=11.87.208.221)
Apr 27 2010 03:49:24 Pnxyncs02 %%01OSPF/6/NBR_CHANGE_E(l)[174815]:Neighbor changes event: neighbor status changed. (ProcessId=101, NeighborAddress=11.87.251.17, NeighborEvent=1-Way, NeighborPreviousState=Full, NeighborCurrentState=Init)

C7609 log:

Apr 27 14:31:09.229 GMT: %OSPF-5-ADJCHG: Process 101, Nbr 11.87.208.221 on GigabitEthernet8/2.2 from DOWN to DOWN, Neighbor Down: Ignore timer expired
pnxyncm02#
Apr 27 14:31:16.366 GMT: %OSPF-5-ADJCHG: Process 101, Nbr 11.87.208.221 on GigabitEthernet8/2.2 from LOADING to FULL, Loading Done
pnxyncm02#
Apr 27 14:31:24.166 GMT: %BGP-5-ADJCHANGE: neighbor 11.87.208.221 Up  
Apr 27 14:33:56.503 GMT: %OSPF-5-ADJCHG: Process 101, Nbr 11.87.208.221 on GigabitEthernet8/2.2 from FULL to DOWN, Neighbor Down: Too many retransmissions
Apr 27 14:34:56.504 GMT: %OSPF-5-ADJCHG: Process 101, Nbr 11.87.208.221 on GigabitEthernet8/2.2 from DOWN to DOWN, Neighbor Down: Ignore timer expired
pnxyncm02#
Apr 27 14:35:04.368 GMT: %OSPF-5-ADJCHG: Process 101, Nbr 11.87.208.221 on GigabitEthernet8/2.2 from LOADING to FULL, Loading Done
Handling Process
See the attachment.
Root Cause
Because the LSDB on C7609 had two LSAs with the same triplet, NE40E discarded the LSAs. For details, see the attachment.
Solution
See the attachment.
Suggestions
When encountering a similar problem occurring on a complex network and with unusual symptoms, analyze a type fault node and simplify the network.

END