Configuring OSPF GR Helper

To avoid traffic interruption and route flapping caused by the active/standby switchover, you can enable OSPF GR.

Usage Scenario

Graceful Restart (GR) is a technology used to ensure normal traffic forwarding and non-stop forwarding of key services during the restart of routing protocols. GR is one of high availability (HA) technologies. HA technologies comprise a set of comprehensive techniques, such as fault-tolerant redundancy, link protection, faulty node recovery, and traffic engineering. As a fault-tolerant redundancy technology, GR is widely used to ensure non-stop forwarding of key services during master/slave switchover and system upgrade.

GR includes the GR restarter and GR helper. NetEngine 8000 F supports the GR Helper only.

Pre-configuration Tasks

Before configuring OSPF GR, complete the following tasks:

Configure IP addresses for interfaces to ensure that neighboring nodes are reachable at the network layer.
Configure basic OSPF functions.

Procedure

Run system-view
The system view is displayed.
Run ospf [ process-id ]
The OSPF view is displayed.
Run opaque-capability enable
The Opaque-LSA capability is enabled.

OSPF supports OSPF GR through Type 9 LSAs (Opaque LSAs). Therefore, before configuring OSPF GR, run the opaque-capability enable command to enable the Opaque-LSA capability.
Configure GR session parameters on the helper.

IETF mode and non-IETF mode are mutually exclusive.
- Configure GR session parameters on the helper in IETF mode.
  1. Run graceful-restart helper-role ignore-external-lsa
    
    The helper does not check AS external LSAs.
  2. Run graceful-restart helper-role planned-only
    
    The helper is configured to support only planned GR.
  3. Choose either of the following configuration as required:
    - Configure a basic ACL rule.
      1. Run graceful-restart [ helper-role { { acl-number acl-number | acl-name acl-name } ^* } | never } ]
        GR session parameters on the helper are configured.
      2. Run quit
        The system view is displayed.
      3. Run acl { name basic-acl-name { basic | [ basic ] number basic-acl-number } | [ number ] basic-acl-number } [ match-order { config | auto } ]
        The basic ACL view is displayed.
      4. Run rule [ rule-id ] [ name rule-name ] { deny | permit } [ fragment-type { fragment | non-fragment | non-subseq | fragment-subseq | fragment-spe-first } | source { source-ip-address { source-wildcard | 0 | src-netmask } | any } | time-range time-name | vpn-instance vpn-instance-name ] ^*
        
        The rule for the basic ACL is configured.
        
        When the rule command is run to configure rules for a named ACL, only the source address range specified by source and the time period specified by time-range are valid as the rules.
    - Configure an IP prefix list.
      
      Run graceful-restart [ helper-role { { ip-prefix ip-prefix-name^* } | never } ]
      
      GR session parameters on the helper are configured.
- Enable the non-IETF mode.
  
  Run graceful-restart non-ietf
  
  GR Helper in non-IETF mode is enabled.
Run commit
The configuration is committed.

Checking the Configuration

Run the display ospf graceful-restart command, and you can view the configurations about OSPF GR.