Courseiva
IPv6Privileged EXEC

show ipv6 ospf

Displays general information about OSPFv3 (IPv6 OSPF) routing processes, including router ID, areas, and interfaces, used to verify OSPFv3 configuration and operation.

Syntax·Privileged EXEC
show ipv6 ospf

When to Use This Command

  • Verify OSPFv3 process is running and check router ID after initial configuration.
  • Troubleshoot OSPFv3 neighbor adjacency issues by reviewing active interfaces and areas.
  • Check OSPFv3 redistribution and routing table references.
  • Monitor OSPFv3 SPF statistics and timer values for performance tuning.

Command Examples

Basic OSPFv3 Process Information

show ipv6 ospf
Routing Process "OSPFv3 (1)" with ID 192.168.1.1
It is an area border router
SPF schedule delay 5 secs, Hold time between two SPFs 10 secs
Minimum LSA interval 5 secs. Minimum LSA arrival 1 secs
Number of external LSA 0. Checksum Sum 0x000000
Number of AS-scoped unknown LSA 0
Number of LSA originated 10
Number of LSA received 5
Number of areas in this router is 2. 2 normal 0 stub 0 nssa
Area BACKBONE(0)
    Number of interfaces in this area is 2
    SPF algorithm executed 4 times
    Number of LSA 5. Checksum Sum 0x02B3F1
Area 1
    Number of interfaces in this area is 1
    SPF algorithm executed 3 times
    Number of LSA 3. Checksum Sum 0x01A2C4

Line 1: OSPFv3 process number (1) and router ID (192.168.1.1). Line 2: Indicates this router is an ABR (Area Border Router). Lines 3-4: SPF and LSA timing parameters. Lines 5-8: Counts of external and unknown LSAs, and originated/received LSAs. Line 9: Total number of areas (2) and their types. Lines 10-15: Area BACKBONE(0) details: 2 interfaces, SPF run count, LSA count and checksum. Lines 16-19: Area 1 details: 1 interface, SPF runs, LSA count.

OSPFv3 with Virtual Links and Filtering

show ipv6 ospf
Routing Process "OSPFv3 (10)" with ID 10.0.0.1
It is an internal router
SPF schedule delay 1 secs, Hold time between two SPFs 5 secs
Minimum LSA interval 5 secs. Minimum LSA arrival 1 secs
Number of external LSA 2. Checksum Sum 0x001234
Number of AS-scoped unknown LSA 0
Number of LSA originated 15
Number of LSA received 12
Number of areas in this router is 1. 1 normal 0 stub 0 nssa
Area 0
    Number of interfaces in this area is 3
    SPF algorithm executed 10 times
    Number of LSA 8. Checksum Sum 0x045678
    Virtual link to router ID 192.168.2.1 is up

Line 1: OSPFv3 process 10, router ID 10.0.0.1. Line 2: Internal router (not ABR/ASBR). Lines 3-4: Faster SPF timers (delay 1s, hold 5s). Lines 5-8: External LSAs present (2), LSA counts. Line 9: Single area (normal). Lines 10-14: Area 0 with 3 interfaces, SPF executed 10 times, LSA count. Line 15: Virtual link to router 192.168.2.1 is operational (important for non-contiguous area 0).

Understanding the Output

The 'show ipv6 ospf' command provides a summary of the OSPFv3 routing process. Key fields: 'Routing Process' shows process ID and router ID (a 32-bit number, often an IPv4 address). 'It is an area border router' or 'internal router' indicates router role; ABR connects multiple areas, ASBR redistributes external routes. SPF schedule delay and hold time affect convergence speed; default values are 5 and 10 seconds. LSA counts help detect instability: rapidly increasing LSA numbers may indicate flapping routes. 'Number of areas' shows area count and types (normal, stub, NSSA). For each area, 'Number of interfaces' indicates OSPFv3-enabled interfaces; if zero, check interface configuration. 'SPF algorithm executed' count rises with topology changes; frequent SPF runs suggest instability. 'Virtual link' status (if present) shows connectivity to backbone area. Good values: router ID unique, SPF runs stable, LSA counts consistent. Bad values: router ID 0.0.0.0 (not set), zero interfaces in an area, or virtual link down.

CCNA Exam Tips

1.

CCNA exam may ask to identify the OSPFv3 router ID from the output; it is always a 32-bit number, often an IPv4 address even in IPv6 OSPF.

2.

Know that 'show ipv6 ospf' does not show neighbors; use 'show ipv6 ospf neighbor' for adjacency details.

3.

The output indicates if a router is an ABR or internal; exam scenarios may test understanding of area border roles.

4.

Be able to interpret SPF timer values and LSA counts to diagnose network stability issues.

Common Mistakes

Confusing OSPFv3 (IPv6) with OSPFv2 (IPv4); the command is 'show ipv6 ospf' not 'show ip ospf'.

Assuming 'show ipv6 ospf' shows neighbor details; it only shows process and area info.

Overlooking the router ID; if it is 0.0.0.0, OSPFv3 is not properly configured.

Misinterpreting 'Number of areas' as number of interfaces; it is the count of configured areas.

Practice for the CCNA 200-301

Test your knowledge with hundreds of CCNA practice questions covering all exam domains.

Practice CCNA Questions