OSPF Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Release

PDF

OSPF Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Release

Configure OSPF restart and nonstop routing features

Updated: June 26, 2026

Want to summarize with AI?

Log in

Configure OSPF restart and nonstop routing features through a focused workflow that preserves the original OSPF command sequence and result checks. Use this task when you need repeatable configuration steps.

Provide a structured and repeatable workflow for configuring OSPF restart and nonstop routing features, ensuring that the original OSPF command sequence is preserved and results can be verified reliably. Use this task when consistent and accurate configuration steps are required.

Procedure

1.

Configure nonstop routing for OSPFv2.

Example:

Router# configure
Router(config)# router ospf isp
Router(config-ospf)# nsr
Router(config-ospf)# commit

Enters mode.
2.

Configure nonstop routing for OSPFv3

Example:

Router# configure
Router(config)# router ospfv3 isp
Router(config-ospf)# nsr
Router(config-ospf)# commit

Enables OSPF routing for the specified routing process, and places the router in router configuration mode. In this example, the OSPF instance is called isp.

3.

Configure a graceful restart for an OSPFv3 process.

Example:

Router# configure
Router(config)# router ospfv3 test
Router(config-ospfv3)# graceful-restart
Router(config-ospfv3)# graceful-restart lifetime 120
Router(config-ospfv3)# graceful-restart interval 120
Router(config-ospfv3)# graceful-restart helper disable
Router# show ospfv3 1 database grace
4.

Verify the state of the graceful restart capability on the local router:

Example:

Router# show ospfv3 1
  
Routing Process “ospfv3 1” with ID 198.51.100.1
Initial SPF schedule delay 5000 msecs
Minimum hold time between two consecutive SPFs 10000 msecs
Maximum wait time between two consecutive SPFs 10000 msecs
Initial LSA throttle delay 0 msecs
Minimum hold time for LSA throttle 5000 msecs
Maximum wait time for LSA throttle 5000 msecs
Minimum LSA arrival 1000 msecs
LSA group pacing timer 240 secs
Interface flood pacing timer 33 msecs
Retransmission pacing timer 66 msecs
Maximum number of configured interfaces 255
Number of external LSA 0. Checksum Sum 00000000
Number of areas in this router is 1. 1 normal 0 stub 0 nssa
Graceful Restart enabled, last GR 11:12:26 ago (took 6 secs)
Area BACKBONE(0)
Number of interfaces in this area is 1
SPF algorithm executed 1 times
Number of LSA 6. Checksum Sum 0x0268a7
Number of DCbitless LSA 0
Number of indication LSA 0
Number of DoNotAge LSA 0
Flood list length 0
5.

Verify the link state for an OSPFv3 instance.

Example:

Router# show ospfv3 1 database grace
  
OSPFv3 Router with ID (192.0.2.1) (Process ID 1)
Grace (Type-11) Link States (Area 0)

  LS age: 2
  LS Type: Grace Links
  Link State ID: 34
  Advertising Router: 192.0.2.1
  LS Seq Number: 80000001
  Checksum: 0x7a4a
  Length: 36
      Grace Period : 90
      Graceful Restart Reason : Software reload/upgrade
6.

Configure OSPF NSF specific to Cisco on your NSF-capable router.

Note

OSPF Cisco NSF for virtual links is not supported.

OSPF NSF requires that all neighbor networking devices be NSF aware, which happens automatically after you install the Cisco IOS XR software image on the router. If an NSF-capable router discovers that it has non-NSF-aware neighbors on a particular network segment, it disables NSF capabilities for that segment. Other network segments composed entirely of NSF-capable or NSF-aware routers continue to provide NSF capabilities.

Neighbors must be NSF aware.

Example:

Router# configure
Router(config)# router ospf 1
Router(config-ospf)# router-id 192.168.4.3
Router(config-ospf)# nsf cisco enforce global
Router(config-ospf)# nsf interval 120
Router(config-ospf)# nsf flush-delay-time 1000
Router(config-ospf)# nsf lifetime 90
Router(config-ospf)# nsf ietf
Router# commit

The OSPF configuration is committed or verified, and the router reflects the intended operational state.

What to do next

Continue with related OSPF verification or tuning tasks that match your deployment workflow.