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The debug ip ospf events output shown in Example 4-6 might appear if any of the following
situations occur:
■ The IP subnet masks for the routers on the same network do not match.
■ The OSPF hello interval for the router does not match the OSPF hello interval that is
configured on a neighbor.
■ The OSPF dead interval for the router does not match the OSPF dead interval that is
configured on a neighbor.
Field Description
Options Hello packet options field contents. (E-bit only. Possible values are 0 and
2; 2 indicates that the area is not a stub; 0 indicates that the area is a stub.)
LLS Options..., Last OOBResync
LLS1 and OOB2 link-state database resynchronization performed
hours:minutes:seconds ago (Cisco NSF3 information). The field indicates
the last successful OOB resynchronization with the Cisco NSF-capable
router.
Dead Timer Due In Expected time before Cisco IOS Software will declare the neighbor dead.
Neighbor Is Up For Number of hours:minutes:seconds since the neighbor went into a twoway
state.
Index Neighbor location in the area-wide and autonomous system–wide
retransmission queue.
Retransmission Queue
Length
Number of elements in the retransmission queue.
Number of Retransmission Number of times update packets have been re-sent during flooding.
First Memory location of the flooding details.
Next Memory location of the flooding details.
Last Retransmission Scan
Length
Number of LSAs in the last retransmission packet.
Maximum Maximum number of LSAs that can be sent in any retransmission packet.
Last Retransmission Scan
Time
Time taken to build the last retransmission packet.
Maximum Maximum time taken to build any retransmission packet.
Table 4-4 show ip ospf neighbor Output (Continued)
Introducing OSPF 153
If a router that is configured for OSPF routing is not seeing an OSPF neighbor on an attached
network, perform the following tasks:
■ Ensure that both routers have been configured with the same IP subnet mask and that the
OSPF hello interval and dead intervals match on both routers.
■ Ensure that both neighbors are part of the same area number and area type.
■ Ensure that authentication type and passwords match.
In Example 4-6, which shows output from the debug ip ospf events command, the neighbor router
and this router are not part of a stub area, denoted by the mismatched E bit. That is, one router is
configured for the area to be a transit area, and the other router is configured for the area to be a
stub area, as explained in RFC 2328.
To display information about each OSPF packet that is received, use the debug ip ospf packet
privileged EXEC command. The no form of this command disables the debugging output.
The debug ip ospf packet command produces one set of information for each packet that is
received. The output varies slightly depending on which authentication is used. The table shows
sample output from the debug ip ospf packet command when Message Digest 5 (MD5)
authentication is used. Example 4-7 shows an OSPF message received and displayed when using
this debug command.