Monitoring Troubleshooting an OSPF Network

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debug ip ospf adjacency Command

The debug ip ospf adjacency command will report to you the various events occurring in relation to the various adjacencies within OSPF. The following example shows that the router detected OSPF adjacency problems on the network to which it is connected. The no form of this command disables debugging output.

    OSPF_Router#debug ip ospf adj    OSPF adjacency events debugging is on    Feb 21 22:48:46.227: OSPF: Rcv pkt from 156.35.254.45, Ethernet1, area    0.0.0.0 : src not on the same network    Feb 21 22:48:56.227: OSPF: Rcv pkt from 156.35.254.45, Ethernet1, area    0.0.0.0 : src not on the same network    Feb 21 22:49:06.227: OSPF: Rcv pkt from 156.35.254.45, Ethernet1, area    0.0.0.0 : src not on the same network    Feb 21 22:49:16.228: OSPF: Rcv pkt from 156.35.254.45, Ethernet1, area    0.0.0.0 : src not on the same network    Feb 21 22:49:26.228: OSPF: Rcv pkt from 156.35.254.45, Ethernet1, area    0.0.0.0 : src not on the same network    Feb 21 22:49:36.228: OSPF: Rcv pkt from 156.35.254.45, Ethernet1, area    0.0.0.0 : src not on the same network    Feb 21 22:49:46.228: OSPF: Rcv pkt from 156.35.254.45, Ethernet1, area    0.0.0.0 : src not on the same network 

The debug message can be interpreted as follows:

  Feb 21 22:48:46.227:. The date and time stamp indicates when the reported event occurred.
  OSPF:. The IP protocol to which the debug message is related.
  Rcv pkt from 156.35.254.45, Ethernet1, area 0.0.0.0 :. The event that occurred which caused debug to report it to you.
  src not on the same network. It defines that the exact problem is.

debug ip ospf events Command

Use the debug ip ospf events EXEC command to display information on Open Shortest Path First (OSPF)-related events, such as adjacencies, flooding information, designated router selection, and shortest path first (SPF) calculation, and so forth. The no form of this command disables debugging output. The basic syntax for this command is as follows:

    [no] debug ip ospf events 

The following is example output generated by the debug ip ospf events command:

    OSPF_router# debug ip ospf events    OSPF:hello with invalid timers on interface Ethernet0    hello interval received 10 configured 10    net mask received 255.255.255.0 configured 255.255.255.0    dead interval received 40 configured 30 

The example debug ip ospf events output might appear if any of the following occurs:

  The IP subnet masks for routers on the same network do not match.
  The OSPF hello interval for the router does not match that configured for a neighbor.
  The OSPF dead interval for the router does not match that configured for a neighbor.

If a router configured for OSPF routing is not seeing an OSPF neighbor on an attached network, do the following:

  Make sure that both routers have been configured with the same IP mask, OSPF hello interval, and OSPF dead interval.
  Make sure that both neighbors are part of the same area type.

debug ip ospf flood Command

This debug command enables you to view the actions and events being generated by OSPF’s Flooding protocol. The no form of this command disables debugging output. The basic syntax for this command is as follows:

 [no] debug ip ospf flood 

This debug command allows for several options to include access lists:

 OSPF_Router# debug ip ospf flood ?    <1-99> Access list    <cr> 

Access list is used to match the LSA ID and only LSA which LSA ID is permitted by the access-list will be displayed. It is used to reduce the debug message generated and make it more useful. For example, if you suspect that the flooding of external LSA is not working, then choose one or two external LSA and use the access list to filter it out with the debug to watch the exact operation of flooding on those LSA.


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OSPF Network Design Solutions
OSPF Network Design Solutions
ISBN: 1578700469
EAN: 2147483647
Year: 1998
Pages: 200
Authors: Tom Thomas

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