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Configuring Application-Specific Link Attribute on an OSPF Interface

Starting in Junos OS and Junos OS Evolved Release 22.2R1, you can advertise different te-attributes such as te-metric, delay-metric, or admin-groups for RSVP and flexible algorithms on the same link. This is done using flexible algorithm specific application-specific link attribute as defined in RFC 8920.

To configure application-specific link attribute based flexible algorithm on an OSPF Interface:

  1. Create an OSPF area.

    For example:

  2. Specify the interface.

    For example:

  3. Configure application-specific link attribute on the OSPF interface of the device.
  4. Specify the attribute group.

    For example:

  5. Configure flexible algorithm specific te-attributes such as te-metric, delay-metric, and admin-groups. Specify the te-metric for the attribute group. The te-metric indicates the metric type based on which OSPFv2 calculates the path.

    For example:

  6. Specify the admin-group for the attribute group.

    For example:

  7. Specify delay-metric for the attribute group.

    For example:

  8. In case delay-metric is not configured, specify advertise-interface-delay to fetch the delay values from the interface configuration hierarchy, that is legacy delay values.

    For example:


    The following configuration can be committed only if all of the following criteria match:

    • An application is associated with the attribute group.

    • Delay-metric is not configured in the hierarchy.

    • Interface level delay configurations are present.

  9. Specify the application for the attribute group. In the current implementation, only flexible algorithm can be configured as an application. An attribute group can have more than one applications associated with it and it equates to a single application-specific link attribute with the application bits set in the standard application identifier bit mask field of the application-specific link attribute sub.
  10. Enter commit from the configuration mode.
  11. Specify strict-asla-based-flex-algorithm to mandate that flexible algorithm path computations use only the links which advertise relevant te-attributes through application-specific link attribute.
  12. Enter commit from the configuration mode.

    To verify your configuration results, use the show protocols operational command.

    The Junos OS and Junos OS Evolved implementation supports application-specific link attribute subTLV to comply with RFC 8920. The application-specific link attribute sub-TLV is a sub-TLV of the OSPFv2 extended Link TLV as defined in RFC 7684.

    To verify the presence of application-specific link attribute sub-TLVs in the OSPF database use the show ospf database extensive operational command.

    The output displays application-specific link attribute sub-TLV fields and attributes.