Nexus 7000 OSPF Adjacency Issues Troubleshoot

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Updated:September 6, 2013
Document ID:116422

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Introduction

This document discusses several common scenarios encountered where the Open Shortest Path First (OSPF) neighbor does not come online as expected. In order to avoid this type of unexpected behavior on Cisco Nexus 7000 Series switches, make sure to follow the guidelines and restrictions about Layer 3 (L3) and Virtual Port Channel (vPC).

Background Information

Before you troubleshoot problems, ensure that the guidelines and restrictions are met. Refer to the Design and Configuration Guide: Best Practices for Virtual Port Channels (vPC) on Cisco Nexus 7000 Series Switches for more information about L3 and vPC.

The procedure used in order to troubleshoot OSPF adjacency issues on the Nexus 7000 is similar to the procedures for Cisco IOS®, but Nexus 7000 has more built-in tools and filters in order to easily identify the issue.

OSPF Adjacency Does Not Come Online

There are times when the OSPF adjacency does not come online. The show ip ospf neighbor command does not show the neighbor.

R3#show ip ospf neighbor
R3#

This issue might be caused by:

  • L2/L3 connectivity issue
  • OSPF not enabled on the interface
  • Interface is defined as passive
  • Mismatched subnet mask
  • Mismatched hello/dead interval
  • Mismatched authentication key
  • Mismatched area ID
  • Mismatched transit/stub/Not-So-Stubby Area (NSSA) option

In order to investigate the issue, check the connectivity, configuration, and Access Control List (ACL)/ Control Plane Policing (CoPP).

Check L2/L3 Connectivity

  1. Check the unicast connectivity with ping.

    • If there is a connectivity issue, discover if it is due to the L2 Internet Service Provider (ISP), a physical port, a Gigabit Interface Converter (GBIC), or a cable.

      Note: Assume that there is no ACL/CoPP blocking the traffic.

    • If the issue is due to faulty hardware or a cable, replace it or move it another port in order to troubleshoot.

  2. Check the multicast connectivity with ping.
    N7K1-RP# ping multicast 224.0.0.5 interface vlan 5
    PING 224.0.0.5 (224.0.0.5): 56 data bytes
    64 bytes from 5.5.5.2: icmp_seq=0 ttl=254 time=1.739 ms
    64 bytes from 5.5.5.2: icmp_seq=1 ttl=254 time=1.253 ms
    64 bytes from 5.5.5.2: icmp_seq=2 ttl=254 time=0.866 ms
    64 bytes from 5.5.5.2: icmp_seq=3 ttl=254 time=1.045 ms
    64 bytes from 5.5.5.2: icmp_seq=4 ttl=254 time=1.89 ms

    --- 224.0.0.5 ping multicast statistics ---
    5 packets transmitted,
    From member 5.5.5.2: 5 packets received, 0.00% packet loss
    --- in total, 1 group member responded ---
    N7K1-RP#

    Verify that the interface is clean and that there are no drops or errors with the show int ethernet 1/1 command.
    N7K1-RP# show int ethernet 1/20 | section RX|TX
      RX
        340213 unicast packets  368092 multicast packets  2 broadcast packets
        708307 input packets  233094927 bytes
        0 jumbo packets  0 storm suppression packets
        0 runts  0 giants  0 CRC/FCS  0 no buffer
        0 input error  0 short frame  0 overrun   0 underrun  0 ignored
        0 watchdog  0 bad etype drop  0 bad proto drop  0 if down drop
        0 input with dribble  0 input discard
        0 Rx pause
      TX
        1374131 unicast packets  324752 multicast packets  3 broadcast packets
        1698886 output packets  196282264 bytes
        0 jumbo packets
        0 output error  0 collision  0 deferred  0 late collision
        0 lost carrier  0 no carrier  0 babble  0 output discard
        0 Tx pause
    N7K1-RP#


  3. Determine if these features drop packets on the incoming Line Card, interface, or CPU.
  • ACL - Inbound/outbound of the interface
  • Quality of Service (QoS) - On the interface
  • CoPP
QoS

N7K1-RP# show policy-map interface ethernet 1/20


Global statistics status :   enabled

Ethernet1/20

  Service-policy (queuing) input:   default-in-policy
    SNMP Policy Index:  301989913

    Class-map (queuing):   in-q1 (match-any)
      queue-limit percent 50
      bandwidth percent 80
      queue dropped pkts : 0 

    Class-map (queuing):   in-q-default (match-any)
      queue-limit percent 50
      bandwidth percent 20
      queue dropped pkts : 0 

  Service-policy (queuing) output:   default-out-policy
    SNMP Policy Index:  301989922

    Class-map (queuing):   out-pq1 (match-any)
      priority level 1
      queue-limit percent 16
      queue dropped pkts : 0 

    Class-map (queuing):   out-q2 (match-any)
      queue-limit percent 1
      queue dropped pkts : 0 

    Class-map (queuing):   out-q3 (match-any)
      queue-limit percent 1
      queue dropped pkts : 0 

    Class-map (queuing):   out-q-default (match-any)
      queue-limit percent 82
      bandwidth remaining percent 25
      queue dropped pkts : 0
                                                                   

CoPP

show policy-map interface control-plane class test1-copp-class-critical

Control Plane
  service-policy input test1-copp-policy-lenient

    class-map test1-copp-class-critical (match-any)
      match access-group name test1-copp-acl-bgp
      match access-group name test1-copp-acl-pim
      match access-group name test1-copp-acl-rip
      match access-group name test1-copp-acl-vpc
      match access-group name test1-copp-acl-bgp6
      match access-group name test1-copp-acl-igmp
      match access-group name test1-copp-acl-lisp
      match access-group name test1-copp-acl-msdp
      match access-group name test1-copp-acl-ospf
      match access-group name test1-copp-acl-pim6
      match access-group name test1-copp-acl-rip6
      match access-group name test1-copp-acl-rise
      match access-group name test1-copp-acl-eigrp
      match access-group name test1-copp-acl-lisp6
      match access-group name test1-copp-acl-ospf6
      match access-group name test1-copp-acl-rise6
      match access-group name test1-copp-acl-eigrp6
      match access-group name test1-copp-acl-otv-as
      match access-group name test1-copp-acl-mac-l2pt
      match access-group name test1-copp-acl-mpls-ldp
      match access-group name test1-copp-acl-mpls-oam
      match access-group name test1-copp-acl-mpls-rsvp
      match access-group name test1-copp-acl-mac-l3-isis
      match access-group name test1-copp-acl-mac-otv-isis
      match access-group name test1-copp-acl-mac-fabricpath-isis
      match protocol mpls router-alert
      match protocol mpls exp 6
      set cos 7
      police cir 39600 kbps bc 375 ms
        conform action: transmit
        violate action: drop 
      module 1:
        conformed 539964945 bytes,
          5-min offered rate 5093 bytes/sec
          peak rate 5213 bytes/sec
        violated 0 bytes,
          5-min violate rate 0 bytes/sec
      module 2:
        conformed 784228080 bytes,
          5-min offered rate 5848 bytes/sec
          peak rate 7692 bytes/sec
        violated 0 bytes,
          5-min violate rate 0 bytes/sec
      module 3:
        conformed 5114206 bytes,
          5-min offered rate 41 bytes/sec
          peak rate 6656 bytes/sec
        violated 0 bytes,
          5-min violate rate 0 bytes/sec

N7K1#    

Check the OSPF Configuration

Use these commands in order to check the OSPF configuration (subnet, hello/dead interval, area ID, area type, authentication key (if any), and not-passive), and ensure that it matches on both sides.

  1. Show run ospf
  2. Show ip ospf 5 interface
  3. Show ip ospf 5

Here is an example of the first command:

N7K1-RP# show run ospf

!Command: show running-config ospf
!Time: Thu May 16 11:27:24 2013

version 6.2(2)
feature ospf

logging level ospf 7

router ospf 5
  router-id 5.5.0.1

interface Vlan5
  ip router ospf 5 area 0.0.0.0

interface loopback5
  ip router ospf 5 area 0.0.0.0

N7K1-RP#

Here is an example of the second command:

N7K1-RP# show ip ospf 5 interface
 Vlan5 is up, line protocol is up
    IP address 5.5.5.1/24, Process ID 5 VRF default, area 0.0.0.0
    Enabled by interface configuration
    State DR, Network type BROADCAST, cost 40
    Index 2, Transmit delay 1 sec, Router Priority 1
    Designated Router ID: 5.5.0.1, address: 5.5.5.1
    Backup Designated Router ID: 5.5.0.2, address: 5.5.5.2
    1 Neighbors, flooding to 1, adjacent with 1
    Timer intervals: Hello 10, Dead 40, Wait 40, Retransmit 5
      Hello timer due in 00:00:00
    No authentication
    Number of opaque link LSAs: 0, checksum sum 0
 loopback5 is up, line protocol is up
    IP address 5.5.0.1/32, Process ID 5 VRF default, area 0.0.0.0
    Enabled by interface configuration
    State LOOPBACK, Network type LOOPBACK, cost 1
    Index 1

N7K1-RP#

Here is an example of the third command:

N7K1-RP# show ip ospf 5

 Routing Process 5 with ID 5.5.0.1 VRF default
 Routing Process Instance Number 3
 Stateful High Availability enabled
 Graceful-restart is configured
   Grace period: 60 state: Inactive
   Last graceful restart exit status: None
 Supports only single TOS(TOS0) routes
 Supports opaque LSA
 Administrative distance 110
 Reference Bandwidth is 40000 Mbps
 SPF throttling delay time of 200.000 msecs,
   SPF throttling hold time of 1000.000 msecs,
   SPF throttling maximum wait time of 5000.000 msecs
 LSA throttling start time of 0.000 msecs,
   LSA throttling hold interval of 5000.000 msecs,
   LSA throttling maximum wait time of 5000.000 msecs
 Minimum LSA arrival 1000.000 msec
 LSA group pacing timer 10 secs
 Maximum paths to destination 8
 Number of external LSAs 0, checksum sum 0
 Number of opaque AS LSAs 0, checksum sum 0
 Number of areas is 1, 1 normal, 0 stub, 0 nssa
 Number of active areas is 1, 1 normal, 0 stub, 0 nssa
 Install discard route for summarized external routes.
 Install discard route for summarized internal routes.
   Area BACKBONE(0.0.0.0)
        Area has existed for 1d10h
        Interfaces in this area: 2 Active interfaces: 2
        Passive interfaces: 0  Loopback interfaces: 1
        No authentication available
        SPF calculation has run 47 times
         Last SPF ran for 0.000542s
        Area ranges are
        Number of LSAs: 3, checksum sum 0x84d4
N7K1-RP#

Check the OSPF Messages

Enter the show ip ospf event-history adjacency command in order to verify that debug messages are sent and received by the OPSF process.

Note: The latest messages appear at the top.

The output shows all the OSPF adjacency messages that are exchanged between OSPF neighbors. When an OSPF adjacency is formed, a router goes through several state changes before it becomes fully adjacent with its neighbor. This output shows all the state changes and the negotiations. If there is an issue (Maximum Transition Unit (MTU), connectivity issues, packet drop), it is reflected in the output.

N7K1-RP# show ip ospf 5 event-history adjacency

Adjacency events for OSPF Process "ospf-5"
2013 May 16 10:50:58.121128 ospf 5 [9386]: :   mtu 1600, opts: 0x42, ddbits:
0, seq: 0x6f40fde4
2013 May 16 10:50:58.121124 ospf 5 [9386]: : Sent DBD with 0 entries to 5.5.5.2
on Vlan5
2013 May 16 10:50:58.121114 ospf 5 [9386]: : Sending DBD to 5.5.5.2 on Vlan5
2013 May 16 10:50:58.118030 ospf 5 [9386]: : Nbr 5.5.5.2: LOADING --> FULL, 
event LDDONE
2013 May 16 10:50:58.115840 ospf 5 [9386]: : Built LS Request packet for 5.5.5.2
with 1 entries
2013 May 16 10:50:58.115835 ospf 5 [9386]: :       Add 5.5.0.2(0x1)5.5.0.2 
(0x8000104e)(0x7ef8) (156) to LSR
2013 May 16 10:50:58.115823 ospf 5 [9386]: : Building LS Request packet to 
5.5.5.2
2013 May 16 10:50:58.112201 ospf 5 [9386]: : Nbr 5.5.5.2: EXCHANGE --> LOADING, 
event EXCHDONE
2013 May 16 10:50:58.112026 ospf 5 [9386]: :   seqnr 0x6f40fde4, dbdbits 0x1, 
mtu 1600, options 0x42
2013 May 16 10:50:58.112022 ospf 5 [9386]: : Got DBD from 5.5.5.2 with 0 entries
2013 May 16 10:50:58.111988 ospf 5 [9386]: :   seqnr 0x6f40fde4, dbdbits 0x1, 
mtu 1600, options 0x42
2013 May 16 10:50:58.111984 ospf 5 [9386]: : Got DBD from 5.5.5.2 with 0 entries
2013 May 16 10:50:58.110169 ospf 5 [9386]: :   mtu 1600, opts: 0x42, ddbits: 0, 
seq: 0x6f40fde3
2013 May 16 10:50:58.110165 ospf 5 [9386]: : Sent DBD with 0 entries to 5.5.5.2 
on Vlan5
2013 May 16 10:50:58.110155 ospf 5 [9386]: : Sending DBD to 5.5.5.2 on Vlan5
2013 May 16 10:50:58.106609 ospf 5 [9386]: :   Added 1 out of 1 LSAs to 
request list
2013 May 16 10:50:58.106606 ospf 5 [9386]: :       Added 5.5.0.2(0x1)5.5.0.2 
(0x8000104e) (0x7ef8) (156) to request list
2013 May 16 10:50:58.106586 ospf 5 [9386]: :   seqnr 0x6f40fde3, dbdbits 0x3, 
mtu 1600, options 0x42
2013 May 16 10:50:58.106582 ospf 5 [9386]: : Got DBD from 5.5.5.2 with 1 entries
2013 May 16 10:50:58.106537 ospf 5 [9386]: :   seqnr 0x6f40fde3, dbdbits 0x3,  
mtu 1600, options 0x42
2013 May 16 10:50:58.106532 ospf 5 [9386]: : Got DBD from 5.5.5.2 with 1 entries
2013 May 16 10:50:58.104462 ospf 5 [9386]: : Built reply LSU with 2 LSAs for 
5.5.5.2 128 bytes
2013 May 16 10:50:58.104439 ospf 5 [9386]: :     Added 5.5.5.2(0x2)5.5.0.2 
(0x80000045) (0xaf32) (156)
2013 May 16 10:50:58.104431 ospf 5 [9386]: :     Added 5.5.0.1(0x1)5.5.0.1 
(0x80000ecf) (0xd834) (8)(O)
2013 May 16 10:50:58.104408 ospf 5 [9386]: : Building reply LSU to 5.5.5.2
2013 May 16 10:50:58.104404 ospf 5 [9386]: :   2 requests in LSR (2 left)
2013 May 16 10:50:58.104370 ospf 5 [9386]: : Answering LSR from 5.5.5.2
2013 May 16 10:50:58.100790 ospf 5 [9386]: : Recv LSR from Nbr 5.5.5.2
2013 May 16 10:50:58.099055 ospf 5 [9386]: :   mtu 1600, opts: 0x42, ddbits:  
0x2, seq: 0x6f40fde2
2013 May 16 10:50:58.099051 ospf 5 [9386]: : Sent DBD with 3 entries to 5.5.5.2 
on Vlan5
2013 May 16 10:50:58.099038 ospf 5 [9386]: : Sending DBD to 5.5.5.2 on Vlan5
2013 May 16 10:50:58.095072 ospf 5 [9386]: :   seqnr 0x6f40fde2, dbdbits 0x7, 
mtu 1600, options 0x42
2013 May 16 10:50:58.095068 ospf 5 [9386]: : Got DBD from 5.5.5.2 with 0 entries
2013 May 16 10:50:58.095024 ospf 5 [9386]: : Nbr 5.5.5.2: EXSTART --> EXCHANGE, 
event NEGDONE
2013 May 16 10:50:58.094895 ospf 5 [9386]: :     We are SLAVE, 5.5.5.2 is master
2013 May 16 10:50:58.094890 ospf 5 [9386]: :   seqnr 0x6f40fde2, dbdbits 0x7, 
mtu 1600, options 0x42
2013 May 16 10:50:58.094886 ospf 5 [9386]: : Got DBD from 5.5.5.2 with 0 entries
2013 May 16 10:50:58.093037 ospf 5 [9386]: :   mtu 1600, opts: 0x42, ddbits: 0x7,
seq: 0x7273409a
2013 May 16 10:50:58.093033 ospf 5 [9386]: : Sent DBD with 0 entries to 5.5.5.2 
on Vlan5
2013 May 16 10:50:58.093029 ospf 5 [9386]: : Sending DBD to 5.5.5.2 on Vlan5
2013 May 16 10:50:58.092915 ospf 5 [9386]: : Nbr 5.5.5.2: INIT --> EXSTART, 
event TWOWAYRCVD
2013 May 16 10:50:58.092862 ospf 5 [9386]: : Nbr 5.5.5.2: TWOWAY --> EXSTART, 
event ADJOK
2013 May 16 10:50:58.092763 ospf 5 [9386]: [9446]: Interface Vlan5  ---> BDR
2013 May 16 10:50:58.092757 ospf 5 [9386]: [9446]: Elected 5.5.0.2 as DR, 
5.5.0.1 as BDR
2013 May 16 10:50:58.092690 ospf 5 [9386]: [9446]:   This nbr 5.5.5.2 promoted 
to current dr
2013 May 16 10:50:58.092687 ospf 5 [9386]: [9446]:   Walking neighbor 5.5.5.2 
(0x93e3524), state TWOWAY
2013 May 16 10:50:58.092683 ospf 5 [9386]: [9446]:   Neighbor not declared DR, 
ignoring
2013 May 16 10:50:58.092680 ospf 5 [9386]: [9446]:   Walking neighbor 5.5.5.1 
(0xac1f7514), state SELF
2013 May 16 10:50:58.092676 ospf 5 [9386]: [9446]: DR election starting
2013 May 16 10:50:58.092673 ospf 5 [9386]: [9446]:   This neighbor is greater 
than 2way
2013 May 16 10:50:58.092670 ospf 5 [9386]: [9446]:   Walking neighbor 5.5.5.2 
(0x93e3524), state TWOWAY
2013 May 16 10:50:58.092666 ospf 5 [9386]: [9446]:   Compare done, new current 
bdr 5.5.5.1
2013 May 16 10:50:58.092663 ospf 5 [9386]: [9446]:   Current BDR set to this 
neighbor
2013 May 16 10:50:58.092660 ospf 5 [9386]: [9446]:   This neighbor is in 
consideration for bdr
2013 May 16 10:50:58.092657 ospf 5 [9386]: [9446]:   This neighbor is greater 
than 2way
2013 May 16 10:50:58.092654 ospf 5 [9386]: [9446]:   Walking neighbor 5.5.5.1 
(0xac1f7514), state SELF
2013 May 16 10:50:58.092650 ospf 5 [9386]: [9446]: BDR election starting
2013 May 16 10:50:58.092647 ospf 5 [9386]: [9446]: DR/BDR Status of this router 
changed, new election run
2013 May 16 10:50:58.092643 ospf 5 [9386]: [9446]:   This nbr 5.5.5.2 promoted 
to current dr
2013 May 16 10:50:58.092639 ospf 5 [9386]: [9446]:   Walking neighbor 5.5.5.2 
(0x93e3524), state TWOWAY
2013 May 16 10:50:58.092635 ospf 5 [9386]: [9446]:   Neighbor not declared DR, 
ignoring
2013 May 16 10:50:58.092632 ospf 5 [9386]: [9446]:   Walking neighbor 5.5.5.1 
(0xac1f7514), state SELF
2013 May 16 10:50:58.092628 ospf 5 [9386]: [9446]: DR election starting
2013 May 16 10:50:58.092625 ospf 5 [9386]: [9446]:   This neighbor is greater 
than 2way
2013 May 16 10:50:58.092622 ospf 5 [9386]: [9446]:   Walking neighbor 5.5.5.2 
(0x93e3524), state TWOWAY
2013 May 16 10:50:58.092618 ospf 5 [9386]: [9446]:   Compare done, new current
bdr 5.5.5.1
2013 May 16 10:50:58.092613 ospf 5 [9386]: [9446]:   Current BDR set to this 
neighbor
2013 May 16 10:50:58.092610 ospf 5 [9386]: [9446]:   This neighbor is in 
consideration for bdr
2013 May 16 10:50:58.092607 ospf 5 [9386]: [9446]:   This neighbor is greater 
than 2way
2013 May 16 10:50:58.092604 ospf 5 [9386]: [9446]:   Walking neighbor 5.5.5.1 
(0xac1f7514), state SELF
2013 May 16 10:50:58.092597 ospf 5 [9386]: [9446]: BDR election starting
2013 May 16 10:50:58.092573 ospf 5 [9386]: [9446]: Current 0.0.0.0 as DR, 
0.0.0.0 as BDR
2013 May 16 10:50:58.092567 ospf 5 [9386]: [9446]: Begin OSPF DR election on 
Vlan5
2013 May 16 10:50:58.092432 ospf 5 [9386]: : Nbr 5.5.5.2: DOWN --> INIT, 
event HELLORCVD

Troubleshoot

If the investigation of the L2/3 connectivity, the configuration, and the OSPF-allowed traffic did not uncover the problem and show the neighbor on the list, open a Cisco Technical Assistance Center (TAC) case. Enter these commands and supply TAC with the information from both neighbors outputs:

  • Show run
  • Show tech-support ospf

OSPF Neighbor Stuck in the Initialization (INIT) State

There are times when the neighbor is stuck in the INIT state, which indicates that the Nexus 7000 sees hello packets from the neighbor, but does not see its router-ID in the hello packet in order to move to the next state of two-way.

router2#show ip ospf neighbor

Neighbor ID     Pri   State     Dead Time   Address         Interface
170.170.5.1     1     INIT/-    00:00:34    170.170.1.1     ethernet 1/1
router-2#

This issue might be caused by:

  • One side is blocking the hello packet with ACL.
  • One side is translating, with Network Address Translation (NAT), the OSPF hello.
  • The multicast capability of one side is broken (L2).

Complete these steps in order to investigate the issue:

  1. Verify that the IP Multicast control plane works.
    N7K4# ping multicast 224.0.0.5 interface Ethernet 1/1

    If you do not see the IP address of the neighbors on the ping results, then there is an issue. Check it on both sides.

  2. Verify that HELLO packets are received from the neighbor.
    N7K4# show ip ospf 5 event-history adjacency

    Note: Outgoing hello packets are not displayed.



  3. Enable the OSPF adjacency debug on each interface, and verify that hello packets are sent.
    N7K4#  debug logfile debug-ospf size 10000
    N7K4#  debug-filter ip ospf 5 interface Ethernet 1/1
    N7K4#  debug ip ospf 5 adjacency detail

    Note: Do not forget to disable debugs.


    N7K4# undebug all
    N7K4# no debug-filter all
    N7K4# clear debug logfile debug-ospf


  4. Verify that packets are sent by OSPF to 224.0.0.5.
    N7K4# debug logfile ospf_vj
    N7K4# debug-filter ip mpacket interface e1/5
    N7K4# debug-filter ip mpacket direction outbound
    N7K4# debug-filter ip mpacket dest 224.0.0.5
    N7K4# debug ip ospf 5 hello

    N7K4# show debug logfile ospf_vj


    N7K1-RP# show debug logfile ospf_vj
    2013 May 16 11:18:55.202270 ospf: 5 [9386] (default)  LAN hello in, ivl 10/40, 
    options 0x02, mask /24, prio 1, dr 5.5.5.1, bdr 5.5.5
    .2 on Vlan5 from 5.5.5.2
    2013 May 16 11:19:00.527640 ospf: 5 [9386] (default)  LAN hello out, ivl 10/40, 
    options 0x02, mask /24, prio 1, dr 5.5.5.1, bdr 5.5.
    5.2 nbrs 1 on Vlan5 (area 0.0.0.0)
    2013 May 16 11:19:03.500785 ospf: 5 [9386] (default)  LAN hello in, ivl 10/40, 
    options 0x02, mask /24, prio 1, dr 5.5.5.1, bdr 5.5.5
    .2 on Vlan5 from 5.5.5.2
    2013 May 16 11:19:09.515150 ospf: 5 [9386] (default)  LAN hello out, ivl 10/40, 
    options 0x02, mask /24, prio 1, dr 5.5.5.1, bdr 5.5.
    5.2 nbrs 1 on Vlan5 (area 0.0.0.0)
    2013 May 16 11:19:10.406800 ospf: 5 [9386] (default)  LAN hello in, ivl 10/40, 
    options 0x02, mask /24, prio 1, dr 0.0.0.0, bdr 0.0.0
    .0 on Vlan5 from 5.5.5.2
    2013 May 16 11:19:10.417602 ospf: 5 [9386] (default)  LAN hello in, ivl 10/40, 
    options 0x02, mask /24, prio 1, dr 0.0.0.0, bdr 0.0.0
    .0 on Vlan5 from 5.5.5.2
    N7K1-RP#


    Note: Do not forget to disable debugs.


    N7K4# clear debug logfile ospf_vj
    N7K4# undebug all
    N7K4# no debug-fil all
    no debug-filter ip mpacket interface Ethernet1/5
    no debug-filter ip mpacket direction outbound
    no debug-filter ip mpacket dest 224.0.0.5
    N7K4#
  5. Verify that the packet is on the ethanalyzer.
    N7K4# ethanalyzer local interface inband capture-filter "ip proto \ospf"

    N7K1# ethanalyzer local interface inband capture-filter "ip proto \ospf" 
    Capturing on inband
    50 packets captured
    2013-05-16 11:06:34.387196      5.5.5.2 -> 224.0.0.5    OSPF Hello Packet
    2013-05-16 11:06:34.397553      5.5.5.2 -> 224.0.0.5    OSPF Hello Packet
    2013-05-16 11:06:38.895343      5.5.5.1 -> 224.0.0.5    OSPF Hello Packet

    Note: There must be one in the Default Virtual Device Context (VDC).

Troubleshoot

If the investigation of the L2/3 connectivity, the configuration, and the OSPF-allowed traffic does not uncover the problem and show that the neighbor becomes FULL, open a TAC case. Enter these commands and supply TAC with the information from both neighbors outputs:

  • Show run
  • Show tech-support ospf

OSPF Neighbor Stuck in a Two-Way State

There are times when the OSPF neighbor is stuck in a two-way state. This scenario is normal in broadcast network types, and reduces the amount of flooding on the wire. This scenario also occurs if all the routers are configured with a priority equal to zero.

Note: Only low-end routers should be configured with a priority of zero so they do not participate in Designated Router (DR) election.

Refer to the Why Does the show ip ospf neighbor Command Reveal Neighbors Stuck in Two-Way State? article for more information.

OSPF Neighbor Stuck in Exstart/Exchange

There are times when the OSPF neighbor is stuck in the Exstart/Exchange state.

If there is MTU mismatch between the interfaces of the OSPF neighbors or they are not able to ping each other with the packet size of the configured MTU due to transmission media, then the OSPF neighbor is stuck in the exstart/exchange state.

router-6# show ip ospf neighbor

Neighbor ID     Pri   State           Dead Time   Address         Interface
170.170.11.7      1   EXCHANGE/  -    00:00:36    170.170.11.7    Serial2.7
router-6#
router-7# show ip ospf neighbor
Neighbor ID     Pri   State           Dead Time   Address         Interface
170.170.11.6      1   EXSTART/  -     00:00:33    170.170.11.6    Serial0.6

router-7#

This issue might be caused by:

  • MTU mismatch - EXCHANGE on one router and EXSTART on the other

    Note: You can configure with the ip ospf mtu-ignore command.

  • Neighbor Router ID (RID) is the same as its neighbor's - EXSTART
  • Unicast is broken - EXCHANGE
    • MTU problem - cannot ping across with more than a certain-length packet
    • ACL blocking unicast - after two-way OSPF sends unicast packet except Point-to-Point (P2P) links
    • NAT translates unicast packet

Complete these steps in order to investigate the issue:

  1. Check the normal ping with a Don't Fragment (DF) bit on and with the maximum IP MTU on the interface.
    N7K4# ping 10.10.12.2 df-bit packet-size 1472

    Note: In Cisco IOS, when you enter the ping x.x.x.x size <size> command, size refers to the IP packet size. In Linux, you specify the Internet Control Message Protocol (ICMP) payload of the ping rather than specifying the IP packet size as in Cisco IOS. As you might already know, Nexus is built on Linux. The MTU is still set to 1,500 bytes - 20 of those bytes are the IP header and another 8 are the ICMP header. 1,500- 20 - 8 = 1,472 bytes of payload. Therefore, the actual IP datagram size is the same as on Cisco IOS, which is 1,500 bytes.



  2. Check if packets are dropped on the incoming interfaces with the show int ethernet 1/1 command.
    N7K1-RP# show int ethernet 1/20 | section RX|TX
    RX
        340213 unicast packets  368092 multicast packets  2 broadcast packets
        708307 input packets  233094927 bytes
        0 jumbo packets  0 storm suppression packets
        0 runts  0 giants  0 CRC/FCS  0 no buffer
        0 input error  0 short frame  0 overrun   0 underrun  0 ignored
        0 watchdog  0 bad etype drop  0 bad proto drop  0 if down drop
        0 input with dribble  0 input discard
        0 Rx pause
      TX
        1374131 unicast packets  324752 multicast packets  3 broadcast packets
        1698886 output packets  196282264 bytes
        0 jumbo packets
        0 output error  0 collision  0 deferred  0 late collision
        0 lost carrier  0 no carrier  0 babble  0 output discard
        0 Tx pause
    N7K1-RP#


  3. Check if CoPP drops the OSPF packet with the show policy-map interface control-plane class test1-copp-class-critical command.
    Control Plane
      service-policy input test1-copp-policy-lenient

        class-map test1-copp-class-critical (match-any)
          match access-group name test1-copp-acl-bgp
          match access-group name test1-copp-acl-pim
          match access-group name test1-copp-acl-rip
          match access-group name test1-copp-acl-vpc
          match access-group name test1-copp-acl-bgp6
          match access-group name test1-copp-acl-igmp
          match access-group name test1-copp-acl-lisp
          match access-group name test1-copp-acl-msdp
          match access-group name test1-copp-acl-ospf
          match access-group name test1-copp-acl-pim6
          match access-group name test1-copp-acl-rip6
          match access-group name test1-copp-acl-rise
          match access-group name test1-copp-acl-eigrp
          match access-group name test1-copp-acl-lisp6
          match access-group name test1-copp-acl-ospf6
          match access-group name test1-copp-acl-rise6
          match access-group name test1-copp-acl-eigrp6
          match access-group name test1-copp-acl-otv-as
          match access-group name test1-copp-acl-mac-l2pt
          match access-group name test1-copp-acl-mpls-ldp
          match access-group name test1-copp-acl-mpls-oam
          match access-group name test1-copp-acl-mpls-rsvp
          match access-group name test1-copp-acl-mac-l3-isis
          match access-group name test1-copp-acl-mac-otv-isis
          match access-group name test1-copp-acl-mac-fabricpath-isis
          match protocol mpls router-alert
          match protocol mpls exp 6
          set cos 7
          police cir 39600 kbps bc 375 ms
            conform action: transmit
            violate action: drop 
          module 1:
            conformed 539964945 bytes,
              5-min offered rate 5093 bytes/sec
              peak rate 5213 bytes/sec
            violated 0 bytes,
              5-min violate rate 0 bytes/sec
          module 2:
            conformed 784228080 bytes,
              5-min offered rate 5848 bytes/sec
              peak rate 7692 bytes/sec
            violated 0 bytes,
              5-min violate rate 0 bytes/sec
          module 3:
            conformed 5114206 bytes,
              5-min offered rate 41 bytes/sec
              peak rate 6656 bytes/sec
            violated 0 bytes,
              5-min violate rate 0 bytes/sec

    N7K1#    


  4. Check the OSPF Database Descriptor (DBD) exchange with the show ip ospf 5 event-history adjacency command or the debug ip ospf 5 adjacency command.
    N7K1-RP#   debug logfile debug-ospf size 10000
    N7K1-RP#   debug-filter ip ospf 5 interface Vlan 5
    N7K1-RP#   debug ip ospf 5 adjacency detail

    Here is an example:
    N7K1-RP#   show debug logfile debug-ospf
    2013 May 20 05:36:23.414376 ospf: 5 [8325] (default)     Nbr 5.5.5.2 FSM start: 
    old state FULL, event HELLORCVD
    2013 May 20 05:36:23.414424 ospf: 5 [8325] (default)     Nbr 5.5.5.2: FULL --> 
    FULL, event HELLORCVD
    2013 May 20 05:36:23.414438 ospf: 5 [8325] (default)     Nbr 5.5.5.2 FSM start: 
    old state FULL, event TWOWAYRCVD
    2013 May 20 05:36:23.414450 ospf: 5 [8325] (default)     Nbr 5.5.5.2: FULL --> 
    FULL, event TWOWAYRCVD
    2013 May 20 05:36:28.832638 ospf: 5 [8325] (default)     Nbr 5.5.5.2 FSM start: 
    old state FULL, event HELLORCVD
    2013 May 20 05:36:28.832674 ospf: 5 [8325] (default)     Nbr 5.5.5.2: FULL --> 
    FULL, event HELLORCVD
    2013 May 20 05:36:28.832695 ospf: 5 [8325] (default)   Nbr 5.5.5.2: transitioning 
    to OneWay - did not find ourselves
    2013 May 20 05:36:28.832709 ospf: 5 [8325] (default)     Nbr 5.5.5.2 FSM start: 
    old state FULL, event ONEWAYRCVD
    2013 May 20 05:36:28.833073 ospf: 5 [8325] (default)     Nbr 5.5.5.2 FSM state 
    changed from FULL to INIT, event ONEWAYRCVD
    2013 May 20 05:36:28.833120 ospf: 5 [8325]   Begin OSPF DR election on Vlan5
    2013 May 20 05:36:28.833140 ospf: 5 [8325]   Current 5.5.0.1 as DR, 5.5.0.2  
    as BDR
    2013 May 20 05:36:28.833177 ospf: 5 [8325]   BDR election starting
    2013 May 20 05:36:28.833196 ospf: 5 [8325]     Walking neighbor 5.5.5.1  
    (0xaec59188),state SELF
    2013 May 20 05:36:28.833211 ospf: 5 [8325]     This neighbor is greater  
    than 2way
    2013 May 20 05:36:28.833235 ospf: 5 [8325]     Walking neighbor 5.5.5.2  
    (0x9777584),  state INIT
    2013 May 20 05:36:28.833249 ospf: 5 [8325]   DR election starting
    2013 May 20 05:36:28.833265 ospf: 5 [8325]     Walking neighbor 5.5.5.1  
    (0xaec59188), state SELF
    2013 May 20 05:36:28.833281 ospf: 5 [8325]     This nbr 5.5.5.1 promoted to 
    current dr
    2013 May 20 05:36:28.833297 ospf: 5 [8325]     Walking neighbor 5.5.5.2  
    (0x9777584), state INIT
    2013 May 20 05:36:28.833404 ospf: 5 [8325]   Elected 5.5.0.1 as DR,  
    0.0.0.0 as BDR
    2013 May 20 05:36:28.833440 ospf: 5 [8325]   Interface Vlan5  ---> DR
    2013 May 20 05:36:28.833456 ospf: 5 [8325] (default)     Nbr 5.5.5.2 FSM start: 
    old state INIT, event ADJOK
    2013 May 20 05:36:28.833474 ospf: 5 [8325] (default) Nbr 5.5.5.2: INIT --> 
    INIT, event ADJOK
    2013 May 20 05:36:28.833492 ospf: 5 [8325] (default) Nbr 5.5.5.2: FULL --> 
    INIT, event ONEWAYRCVD
    2013 May 20 05:36:28.843309 ospf: 5 [8325] (default)     Nbr 5.5.5.2 FSM start: 
    old state INIT, event HELLORCVD
    2013 May 20 05:36:28.843339 ospf: 5 [8325] (default) Nbr 5.5.5.2: INIT --> 
    INIT, event HELLORCVD
    2013 May 20 05:36:28.843357 ospf: 5 [8325] (default)   Nbr 5.5.5.2: transitioning 
    to OneWay - did not find ourselves
    2013 May 20 05:36:28.843370 ospf: 5 [8325] (default)     Nbr 5.5.5.2 FSM start: 
    old state INIT, event ONEWAYRCVD
    2013 May 20 05:36:28.843386 ospf: 5 [8325] (default) Nbr 5.5.5.2: INIT --> 
    INIT, event ONEWAYRCVD
    2013 May 20 05:36:34.244541 ospf: 5 [8325] (default)   Got DBD from 5.5.5.2 
    with 0 entries
    2013 May 20 05:36:34.244567 ospf: 5 [8325] (default)     seqnr 0x9247f5e, 
    dbdbits 0x7, mtu 1600, options 0x42
    2013 May 20 05:36:34.244622 ospf: 5 [8325] (default)     Nbr 5.5.5.2 FSM start: 
    old state INIT, event TWOWAYRCVD
    2013 May 20 05:36:34.244798 ospf: 5 [8325] (default)     Nbr 5.5.5.2 FSM state 
    changed from INIT to EXSTART, event ADJOK
    2013 May 20 05:36:34.244859 ospf: 5 [8325]   Begin OSPF DR election on Vlan5
    2013 May 20 05:36:34.244880 ospf: 5 [8325]   Current 5.5.0.1 as DR, 0.0.0.0 
    as BDR
    2013 May 20 05:36:34.244916 ospf: 5 [8325]   BDR election starting
    2013 May 20 05:36:34.244935 ospf: 5 [8325]     Walking neighbor 5.5.5.1 
    (0xaec59288), state SELF
    2013 May 20 05:36:34.244949 ospf: 5 [8325]     This neighbor is greater 
    than 2way
    2013 May 20 05:36:34.244965 ospf: 5 [8325]     Walking neighbor 5.5.5.2 
    (0x9777584), state EXSTART
    2013 May 20 05:36:34.244978 ospf: 5 [8325]     This neighbor is greater 
    than 2way
    2013 May 20 05:36:34.244991 ospf: 5 [8325]     This neighbor is in consideration 
    for bdr
    2013 May 20 05:36:34.245004 ospf: 5 [8325]     Current BDR set to this neighbor
    2013 May 20 05:36:34.245019 ospf: 5 [8325]     Compare done, new current 
    bdr 5.5.5.2
    2013 May 20 05:36:34.245033 ospf: 5 [8325]   DR election starting
    2013 May 20 05:36:34.245049 ospf: 5 [8325]     Walking neighbor 5.5.5.1 
    (0xaec59288), state SELF
    2013 May 20 05:36:34.245065 ospf: 5 [8325]     This nbr 5.5.5.1 promoted to 
    current dr
    2013 May 20 05:36:34.245080 ospf: 5 [8325]     Walking neighbor 5.5.5.2 
    (0x9777584), state EXSTART
    2013 May 20 05:36:34.245094 ospf: 5 [8325]     Neighbor not declared DR, 
    ignoring
    2013 May 20 05:36:34.245202 ospf: 5 [8325]   Elected 5.5.0.1 as DR, 
    5.5.0.2 as BDR
    2013 May 20 05:36:34.245247 ospf: 5 [8325]   Interface Vlan5  ---> DR
    2013 May 20 05:36:34.245262 ospf: 5 [8325] (default)     Nbr 5.5.5.2 FSM start: 
    old state EXSTART, event ADJOK
    2013 May 20 05:36:34.245299 ospf: 5 [8325] (default) Nbr 5.5.5.2: 
    EXSTART --> EXSTART, event ADJOK
    2013 May 20 05:36:34.245318 ospf: 5 [8325] (default) Nbr 5.5.5.2: 
    INIT --> EXSTART, event TWOWAYRCVD
    2013 May 20 05:36:34.245335 ospf: 5 [8325] (default)       We are SLAVE, 
    5.5.5.2 is master
    2013 May 20 05:36:34.245348 ospf: 5 [8325] (default)     Nbr 5.5.5.2 FSM start: 
    old state EXSTART, event NEGDONE
    2013 May 20 05:36:34.245366 ospf: 5 [8325] (default)         Preparing DBD exchange 
    for nbr 5.5.5.2, 387/5
    2013 May 20 05:36:34.245463 ospf: 5 [8325] (default)     Nbr 5.5.5.2 FSM state 
    changed from EXSTART to EXCHANGE, event NEGDONE
    2013 May 20 05:36:34.245483 ospf: 5 [8325] (default) Nbr 5.5.5.2: EXSTART --> 
    EXCHANGE, event NEGDONE
    2013 May 20 05:36:34.245843 ospf: 5 [8325] (default)   Got DBD from 5.5.5.2 
    with 0 entries
    2013 May 20 05:36:34.245862 ospf: 5 [8325] (default)     seqnr 0x9247f5e, 
    dbdbits 0x7, mtu 1600, options 0x42
    2013 May 20 05:36:34.245997 ospf: 5 [8325] (default) Sending DBD to 
    5.5.5.2 on Vlan5
    2013 May 20 05:36:34.246031 ospf: 5 [8325] (default)       Add 5.5.0.2(0x1)5.5.0.2 
    (0x80000084) (0x2c26) (109) to DBD
    2013 May 20 05:36:34.246062 ospf: 5 [8325] (default)       Add 5.5.0.1(0x1)5.5.0.1 
    (0x8000007f) (0xa3c7) (5)(O) to DBD
    2013 May 20 05:36:34.246078 ospf: 5 [8325] (default)       Filled DBD to 5.5.5.2 
    with 2 entries
    2013 May 20 05:36:34.246111 ospf: 5 [8325] (default) Sent DBD with 2 entries to 
    5.5.5.2 on Vlan5
    2013 May 20 05:36:34.246128 ospf: 5 [8325] (default)   mtu 1600, opts: 0x42, 
    ddbits: 0x2, seq: 0x9247f5e
    2013 May 20 05:36:34.258616 ospf: 5 [8325] (default) Recv LSR from Nbr 5.5.5.2
    2013 May 20 05:36:34.258634 ospf: 5 [8325] (default)       schedule flood
    2013 May 20 05:36:34.258674 ospf: 5 [8325] (default)   Answering LSR from 5.5.5.2
    2013 May 20 05:36:34.258690 ospf: 5 [8325] (default)     1 requests in LSR (1 left)
    2013 May 20 05:36:34.258707 ospf: 5 [8325] (default) Building reply LSU to 5.5.5.2
    2013 May 20 05:36:34.258726 ospf: 5 [8325] (default)       Found requested LSA 
    5.5.0.1(1)5.5.0.1 for 5.5.5.2
    2013 May 20 05:36:34.258791 ospf: 5 [8325] (default)       Added 5.5.0.1(0x1)
    5.5.0.1 (0x8000007f) (0xa3c7) (5)(O)
    2013 May 20 05:36:34.258872 ospf: 5 [8325] (default) Built reply LSU with 1 LSAs 
    for 5.5.5.2 96 bytes
    2013 May 20 05:36:34.286591 ospf: 5 [8325] (default)   Got DBD from 5.5.5.2 
    with 2 entries
    2013 May 20 05:36:34.286615 ospf: 5 [8325] (default)     seqnr 0x9247f5f, 
    dbdbits 0x3, mtu 1600, options 0x42
    2013 May 20 05:36:34.286751 ospf: 5 [8325] (default)   Got DBD from 5.5.5.2 
    with 2 entries
    2013 May 20 05:36:34.286784 ospf: 5 [8325] (default)     seqnr 0x9247f5f, 
    dbdbits 0x3, mtu 1600, options 0x42
    2013 May 20 05:36:34.286804 ospf: 5 [8325] (default)         Found 5.5.5.1(0x2)
    5.5.0.1 (0x80000004) (0x46de) (111) in DBD
    2013 May 20 05:36:34.286870 ospf: 5 [8325] (default)         Added 5.5.5.1(0x2)
    5.5.0.1 (0x80000004) (0x46de) (111)(DO) to request li
    st
    2013 May 20 05:36:34.286889 ospf: 5 [8325] (default)         Found 5.5.0.2(0x1)
    5.5.0.2 (0x80000085) (0x91d0) (5) in DBD
    2013 May 20 05:36:34.286917 ospf: 5 [8325] (default)         Added 5.5.0.2(0x1)
    5.5.0.2 (0x80000084) (0x2c26) (109) to request list
    2013 May 20 05:36:34.286932 ospf: 5 [8325] (default)     Added 2 out of 2 LSAs 
    to request list
    2013 May 20 05:36:34.287046 ospf: 5 [8325] (default) Sending DBD to 
    5.5.5.2 on Vlan5
    2013 May 20 05:36:34.287066 ospf: 5 [8325] (default)       Filled DBD to 
    5.5.5.2 with 0 entries
    2013 May 20 05:36:34.287101 ospf: 5 [8325] (default) Sent DBD with 0 entries to 
    5.5.5.2 on Vlan5
    2013 May 20 05:36:34.287121 ospf: 5 [8325] (default)   mtu 1600, opts: 0x42, 
    ddbits: 0, seq: 0x9247f5f
    2013 May 20 05:36:34.291760 ospf: 5 [8325] (default)   Got DBD from 5.5.5.2 
    with 0 entries
    2013 May 20 05:36:34.291789 ospf: 5 [8325] (default)     seqnr 0x9247f60, 
    dbdbits 0x1, mtu 1600, options 0x42
    2013 May 20 05:36:34.291915 ospf: 5 [8325] (default)   Got DBD from 5.5.5.2 
    with 0 entries
    2013 May 20 05:36:34.291934 ospf: 5 [8325] (default)     seqnr 0x9247f60, 
    dbdbits 0x1, mtu 1600, options 0x42
    2013 May 20 05:36:34.291953 ospf: 5 [8325] (default)     Nbr 5.5.5.2 FSM start: 
    old state EXCHANGE, event EXCHDONE
    2013 May 20 05:36:34.292101 ospf: 5 [8325] (default)     Nbr 5.5.5.2 FSM state 
    changed from EXCHANGE to LOADING, event EXCHDONE
    2013 May 20 05:36:34.292124 ospf: 5 [8325] (default) Nbr 5.5.5.2: EXCHANGE --> 
    LOADING, event EXCHDONE
    2013 May 20 05:36:34.293200 ospf: 5 [8325] (default) Building LS Request packet 
    to 5.5.5.2
    2013 May 20 05:36:34.293231 ospf: 5 [8325] (default)         Add 5.5.0.2(0x1)
    5.5.0.2 (0x80000084) (0x2c26) (110) to LSR
    2013 May 20 05:36:34.293262 ospf: 5 [8325] (default)         Add 5.5.5.1(0x2)
    5.5.0.1 (0x80000004) (0x46de) (111)(DO) to LSR
    2013 May 20 05:36:34.293281 ospf: 5 [8325] (default) Built LS Request packet for 
    5.5.5.2 with 2 entries
    2013 May 20 05:36:34.297954 ospf: 5 [8325] (default)     Nbr 5.5.5.2 FSM start: 
    old state LOADING, event LDDONE
    2013 May 20 05:36:34.298069 ospf: 5 [8325] (default)     Nbr 5.5.5.2 FSM state 
    changed from LOADING to FULL, event LDDONE
    2013 May 20 05:36:34.298206 ospf: 5 [8325] (default) Nbr 5.5.5.2: LOADING --> 
    FULL, event LDDONE
    2013 May 20 05:36:34.299179 ospf: 5 [8325] (default) Sending DBD to 5.5.5.2 
    on Vlan5
    2013 May 20 05:36:34.299199 ospf: 5 [8325] (default)       Filled DBD to 5.5.5.2 
    with 0 entries
    2013 May 20 05:36:34.299233 ospf: 5 [8325] (default) Sent DBD with 0 entries to 
    5.5.5.2 on Vlan5
    2013 May 20 05:36:34.299253 ospf: 5 [8325] (default)   mtu 1600, opts: 0x42, 
    ddbits: 0, seq: 0x9247f60
    2013 May 20 05:36:38.746942 ospf: 5 [8325] (default)     Nbr 5.5.5.2 FSM start: 
    old state FULL, event HELLORCVD
    2013 May 20 05:36:38.747010 ospf: 5 [8325] (default)     Nbr 5.5.5.2: FULL --> 
    FULL, event HELLORCVD
    2013 May 20 05:36:38.747024 ospf: 5 [8325] (default)     Nbr 5.5.5.2 FSM start: 
    old state FULL, event TWOWAYRCVD
    2013 May 20 05:36:38.747046 ospf: 5 [8325] (default)     Nbr 5.5.5.2: FULL --> 
    FULL, event TWOWAYRCVD
    2013 May 20 05:36:38.747073 ospf: 5 [8325] (default)   Different BDR in hello, 
    invoking nbrchange
    2013 May 20 05:36:38.747090 ospf: 5 [8325] (default)   Neighbor 
    priority/options/DR/BDR value changed
    2013 May 20 05:36:38.747265 ospf: 5 [8325]   Begin OSPF DR election on Vlan5
    2013 May 20 05:36:38.747288 ospf: 5 [8325]   Current 5.5.0.1 as DR,
     5.5.0.2 as BDR
    2013 May 20 05:36:38.747329 ospf: 5 [8325]   BDR election starting
    2013 May 20 05:36:38.747348 ospf: 5 [8325]     Walking neighbor 5.5.5.1 
    (0xaec59478), state SELF
    2013 May 20 05:36:38.747362 ospf: 5 [8325]     This neighbor is greater 
    than 2way
    2013 May 20 05:36:38.747648 ospf: 5 [8325]     Walking neighbor 5.5.5.2 
    (0x9777584), state FULL
    2013 May 20 05:36:38.747662 ospf: 5 [8325]     This neighbor is greater 
    than 2way
    2013 May 20 05:36:38.747676 ospf: 5 [8325]     This neighbor is in consideration 
    for bdr
    2013 May 20 05:36:38.747689 ospf: 5 [8325]     Current BDR set to this neighbor
    2013 May 20 05:36:38.747705 ospf: 5 [8325]     Compare done, new current bdr 
    5.5.5.2
    2013 May 20 05:36:38.747733 ospf: 5 [8325]   DR election starting
    2013 May 20 05:36:38.747750 ospf: 5 [8325]     Walking neighbor 5.5.5.1 
    (0xaec59478), state SELF
    2013 May 20 05:36:38.747766 ospf: 5 [8325]     This nbr 5.5.5.1 promoted to 
    current dr
    2013 May 20 05:36:38.747782 ospf: 5 [8325]     Walking neighbor 5.5.5.2 
    (0x9777584), state FULL
    2013 May 20 05:36:38.747796 ospf: 5 [8325]     Neighbor not declared DR, 
    ignoring
    2013 May 20 05:36:38.747948 ospf: 5 [8325]   Elected 5.5.0.1 as DR, 
    5.5.0.2 as BDR
    2013 May 20 05:36:38.748004 ospf: 5 [8325]   Interface Vlan5  ---> DR

    Note: Do not forget to disable debugs.


    N7K1-RP#  clear debug logfile debug-ospf
    N7K1-RP#  undebug all
    N7K1-RP#  no debug-fil all

    Investigation tips:

    1. Look for mismatched MTU messages.
    2. Follow the sequence number and look for a retransmission due to DBD drop.
    3. Check for receipt of an unexpected DBD sequence number.

Troubleshoot

If the investigation of the L2/3 connectivity, the configuration, and the OSPF-allowed traffic did not uncover the problem and show that the neighbor is online, open a TAC case. Enter these commands and supply TAC with the information from both neighbors outputs:

  • Show run
  • Show tech-support ospf

OSPF Neighbor Stuck in a Loading State

There are times when the OSPF neighbor is stuck in a loading state.

This issue might be caused by:

  • A Link State (LS) request is made, and the neighbor sends a bad packet or memory corruption exists.
    • Enter the show IP OSPF bad command in order to see the bad Link State Advertisement (LSA).
    • The show log command shows the OSPF-4-BADLSATYPE message.
    • An LS request is made, and the neighbor ignores the request.

If a router receives an outdated, corrupted, or missing LSA, OSPF stays in a loading state, and generates the OSPF-4-BADLSA error message.

Enter this command in order to investigate:

7K1-RP# show ip ospf traffic vlan 5
 OSPF Process ID 5 VRF default, Packet Counters (cleared 1d12h ago)
 Interface Vlan5, Area 0.0.0.0
  Total: 15214 in, 15214 out
  LSU transmissions: first 88, rxmit 9(13), for req 0, nbr xmit 289801235
  Flooding packets output throttled (IP/tokens): 0 (0/0)
  Ignored LSAs: 0, LSAs dropped during SPF: 0
  LSAs dropped during graceful restart: 0
  Errors: drops in        0, drops out       0, errors in       0,
          errors out      0, hellos in       0, dbds in         0,
          lsreq in        0, lsu in          0, lsacks in       0,
          unknown in      0, unknown out     0, no ospf         0,
          bad version     0, bad crc         0, dup rid         0,
          dup src         0, invalid src     0, invalid dst     0,
          no nbr          0, passive         0, wrong area      0,
          pkt length      0, nbr changed rid/ip addr            0
          bad auth        0
 
           hellos       dbds     lsreqs       lsus       acks
   In:      14957         42         13        108         94
  Out:      14957         46         14        110         87
 
N7K1-RP#

Troubleshoot

If the investigation of the L2/3 connectivity, the configuration, and the OSPF-allowed traffic did not uncover the problem and show that the neighbor is online, open a TAC case. Enter these commands and supply TAC with the information from both neighbors outputs:

  • Show log logfile
  • Show tech-support ospf

Revision History

Revision Publish Date Comments
1.0
06-Sep-2013
Initial Release
TAC Authored

Contributed by Cisco Engineers

  • Vijay Shanmuganathan
    Cisco TAC Engineer.

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