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OSPFPrivileged EXEC

show ip ospf

Displays general information about OSPF routing process, including router ID, areas, and LSDB statistics, used to verify OSPF configuration and operational status.

Syntax·Privileged EXEC
show ip ospf

When to Use This Command

  • Verify OSPF process is running and check router ID after initial configuration.
  • Troubleshoot OSPF adjacency issues by confirming the router ID and area configuration.
  • Check OSPF LSDB statistics to monitor memory usage and database size.
  • Confirm OSPF is enabled on the correct interfaces and in the correct area.

Command Examples

Basic OSPF Process Information

show ip ospf
Routing Process "ospf 1" with ID 192.168.1.1
Start time: 00:02:34.567, Time elapsed: 00:15:22.123
Supports only single TOS(TOS0) routes
Supports opaque LSA
Supports Link-local Signaling (LLS)
Supports area transit capability
Router is not originating router-LSAs with maximum metric
Initial SPF schedule delay 5000 msecs
Minimum hold time between two consecutive SPFs 10000 msecs
Maximum wait time between two consecutive SPFs 10000 msecs
Incremental-SPF disabled
Minimum LSA interval 5 secs
Minimum LSA arrival 1000 msecs
LSA group pacing timer 240 secs
Interface flood pacing timer 33 msecs
Retransmission pacing timer 66 msecs
Number of external LSA 0. Checksum Sum 0x000000
Number of opaque AS LSA 0. Checksum Sum 0x000000
Number of DCbitless external and opaque AS LSA 0
Number of DoNotAge external and opaque AS LSA 0
Number of areas in this router is 1. 1 normal 0 stub 0 nssa
Number of areas transit capable is 0
External flood list length 0
IETF NSF helper support enabled
Cisco NSF helper support enabled
Reference bandwidth unit is 100 mbps
Area BACKBONE(0)
    Number of interfaces in this area is 2
    Area has no authentication
    SPF algorithm executed 4 times
    Area ranges are
    Number of LSA 3. Checksum Sum 0x00A5B6
    Number of opaque link LSA 0. Checksum Sum 0x000000
    Number of DCbitless LSA 0
    Number of indication LSA 0
    Number of DoNotAge LSA 0
    Flood list length 0

Line 1: OSPF process number and router ID. Line 2: Uptime since OSPF started. Lines 3-6: Supported features. Lines 7-14: SPF timers and LSA pacing. Lines 15-18: External LSA counts. Lines 19-20: Area summary. Lines 21-22: NSF helper status. Line 23: Reference bandwidth. Lines 24-33: Area 0 details including interface count, authentication, SPF runs, LSA count.

OSPF Process with Multiple Areas

show ip ospf
Routing Process "ospf 1" with ID 10.0.0.1
Start time: 01:23:45.678, Time elapsed: 2d05h
...
Number of areas in this router is 2. 1 normal 1 stub 0 nssa
Area BACKBONE(0)
    Number of interfaces in this area is 1
    ...
Area 1
    Number of interfaces in this area is 1
    It is a stub area
    ...

Shows two areas: backbone (0) and a stub area (1). The stub area line indicates area type. Useful for verifying multi-area OSPF design.

Understanding the Output

The 'show ip ospf' command provides a high-level overview of the OSPF process. Key fields: 'Routing Process' shows process ID and router ID; 'Start time' indicates how long OSPF has been running; 'Number of areas' tells how many areas the router participates in; each area section lists interfaces, authentication, SPF execution count, and LSA count. A healthy OSPF process should have a router ID that is reachable, SPF algorithm executed a reasonable number (not excessively high), and LSA counts that are stable. Watch for 'Maximum metric' originating (indicates a problem), high SPF counts (possible flapping), or missing areas (misconfiguration).

CCNA Exam Tips

1.

CCNA exam may ask to identify the router ID from the output; remember it's the highest loopback or active interface IP.

2.

Know that 'Number of areas' indicates if the router is an ABR (multiple areas) or internal router (single area).

3.

Be able to differentiate between normal, stub, and NSSA areas from the area description line.

4.

Remember that SPF algorithm execution count increases with network changes; a high count may indicate instability.

Common Mistakes

Confusing router ID with process ID; router ID is an IP address, process ID is a number.

Assuming OSPF is running if the command returns output; verify the router ID is correct and areas are present.

Misinterpreting 'Number of areas' as number of interfaces; it's the count of distinct OSPF areas configured.

Related Commands

show ip ospf database

Displays the OSPF link-state database (LSDB) to verify OSPF adjacencies, check for missing or corrupt LSAs, and troubleshoot OSPF routing issues.

show ip ospf interface

Displays OSPF interface parameters and status, used to verify OSPF configuration and troubleshoot neighbor relationships.

show ip ospf neighbor

Displays OSPF neighbor information to verify adjacency formation and troubleshoot OSPF neighbor relationships.

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