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Configuring IP-AFT Prefix Filtering

In the OpenConfig Abstract Forwarding Table (OC-AFT) model, the Forwarding Information Base Telemetry Daemon (FIBTD) not only translates the FIB state to the external collector, but also enables you to configure prefix filtering on the target device (source). With prefix filtering, you control the flow of data from your device to the collector. Only interfaces with the required prefixes and their corresponding next-hop and next-hop group containers are exported to the OC-AFT collector.

Reducing the set of interfaces to only those with prefixes of interest decreases the overall CPU and resource usage on Routing Engines, FPCs, and MPCs.

To configure prefix filtering:

  1. In configuration mode, go to the [edit system fib-streaming] hierarchy level and add the forwarding information base (FIB) table you want to target using the table statement.
  2. Include the family statement and specify either inet (IPv4) or inet6 (IPv6).
  3. Use the prefix statement to add the address prefix following; here, the address is 2001:db8:0000:0000:250:af:34ff:fe26/64 and the prefix is 2001:db8:0000:0000:250:af:34ff:fe26/64
  4. In Junos OS, to verify if prefix filtering is configured, use the operational mode command show fib-streaming state to display the Operation mode. The value prefix-filter confirms that prefix filtering mode is enabled.

    See below the sample show command output in Junos OS:

    In Junos OS Evolved, the value prefix-filter-on-change confirms that prefix filtering mode is enabled, else the value is on-change for non-prefix filtering mode.

Note:

For Junos OS: Export data from your source (target) to a collector using the sensor /network-instances/network-instance/afts/. When using prefix-filter mode, we recommend you use streaming subscription mode at a sampling frequency of 5 minutes or more and that all collectors have the same sampling frequency. If you are using non-prefix-filter mode, we recommend you use ON_CHANGE subscription mode. You can also export data using User Datagram Protocol (UDP).

For Junos OS Evolved: The recommended usage is always ON_CHANGE subscription mode, for both prefix-filtering and non-prefix filtering mode.

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