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New Member

OSPF Session flapping

Hi Experts

i have ospf session  flapping between 2 routers . i have checked the physical connectivity while it works fine,where should i investigate?why that happend

jamil

6 REPLIES
Super Bronze

OSPF Session flapping

Disclaimer

The   Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose.   Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of  this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising  out of the use or inability to use the posting's information even if  Author has been advised of the possibility of such damage.

Posting

If for any reason the two OSPF neighbors don't get their expected number of keepalives (while there's other routed traffic), the OSPF adjacency will drop.  After it drops, new OSPF hellos can re-establish the neighbors (when there's no longer routed traffic).  This combination is one possible reason for a flapping OSPF relationship.

You check traffic loading (while OSPF is up across the link), keep alive settings, and packet corruption.  Also check the logs, and you might enable OSPF debugging.

New Member

OSPF Session flapping

Hi Joseph

How to check the below?

You check traffic loading (while OSPF is up across the link), keep alive  settings, and packet corruption.  Also check the logs

thanks.

OSPF Session flapping

Jamil,

You can do the following to help find the cause:

debug ip ospf adj

debug ip ospf events

HTH,

John

HTH, John *** Please rate all useful posts ***
Super Bronze

OSPF Session flapping

Disclaimer

The    Author of this posting offers the information contained within this  posting without consideration and with the reader's understanding that  there's no implied or expressed suitability or fitness for any  purpose.   Information provided is for informational purposes only and  should not be construed as rendering professional advice of any kind.  Usage of  this posting's information is solely at reader's own risk.

Liability Disclaimer

In  no event shall Author be liable for any damages whatsoever (including,  without limitation, damages for loss of use, data or profit) arising   out of the use or inability to use the posting's information even if   Author has been advised of the possibility of such damage.

Posting

#sh ip os in g1/0/1

GigabitEthernet1/0/1 is up, line protocol is up (connected)

  Internet Address 10.148.252.222/30, Area 80

  Process ID 100, Router ID 10.148.0.8, Network Type POINT_TO_POINT, Cost: 1

  Transmit Delay is 1 sec, State POINT_TO_POINT

  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5

    oob-resync timeout 40

    Hello due in 00:00:07

  Supports Link-local Signaling (LLS)

  Cisco NSF helper support enabled

  IETF NSF helper support enabled

  Index 5/5, flood queue length 0

  Next 0x0(0)/0x0(0)

  Last flood scan length is 1, maximum is 1

  Last flood scan time is 0 msec, maximum is 9 msec

  Neighbor Count is 1, Adjacent neighbor count is 1

    Adjacent with neighbor 10.148.0.12

  Suppress hello for 0 neighbor(s)

#sh int g1/0/1

GigabitEthernet1/0/1 is up, line protocol is up (connected)

  Hardware is Gigabit Ethernet, address is 0017.9457.2841 (bia 0017.9457.2841

  Description: Link to

  Internet address is 10.148.252.222/30

  MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,

     reliability 255/255, txload 1/255, rxload 2/255

  Encapsulation ARPA, loopback not set

  Keepalive not set

  Full-duplex, 1000Mb/s, link type is auto, media type is 1000BaseSX SFP

  input flow-control is off, output flow-control is unsupported

  ARP type: ARPA, ARP Timeout 04:00:00

  Last input 00:00:00, output 00:00:00, output hang never

  Last clearing of "show interface" counters never

  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0

  Queueing strategy: fifo

  Output queue: 0/0 (size/max)

  5 minute input rate 10251000 bits/sec, 1155 packets/sec

  5 minute output rate 1000000 bits/sec, 744 packets/sec

     7445784488 packets input, 6883880784658 bytes, 0 no buffer

     Received 9443775 broadcasts (0 IP multicasts)

     0 runts, 0 giants, 0 throttles

     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored

     0 watchdog, 9443719 multicast, 0 pause input

     0 input packets with dribble condition detected

     5611379294 packets output, 1424099267233 bytes, 0 underruns

     0 output errors, 0 collisions, 0 interface resets

     0 babbles, 0 late collision, 0 deferred

     0 lost carrier, 0 no carrier, 0 PAUSE output

     0 output buffer failures, 0 output buffers swapped out

OSPF Session flapping

ibrahim,

please do some debugs and provide the logs here to see what could be causing the issue. Also as Joe suggested check the load and all but some ospf debug should reveal whats happening. that informatino should help us fix the issue

HTH

Kishore

New Member

OSPF Session flapping

Thanks you all guys , Thanks Joseph for the details

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