To create a BGP prefix list filter

General information

Perform this procedure to create a BGP prefix list filter. To generate a filtered prefix list, see To retrieve a filtered BGP prefix list .

Consider the following when you create a BGP prefix list:

  • BGP prefix lists can be retrieved from only one AS at a time

  • You can filter BGP prefixes based on:

    • protocol—IPv4 or VPN IPv4

    • EVPN

    • RT (VPN IPv4 only)

    • route distinguisher (VPN IPv4 only)

    • prefix health (VPN IPv4 only)

    • originating AS

    • MED

    • local preference

    • next hop

    • route type—internal, external, or both

    • AS path length

Steps
 

Choose Tools→Route Analysis→Prefix List from the NFM-P main menu. The Prefix Form opens.


Click Create and choose BGP Prefix Filter. The BGP Prefix List Filter form opens.


Configure the required parameters.

Note: When you choose EVPN as the address type, the EVPN Route Type panel is available.

The Prefix Lower Range and Prefix Higher Range parameters are configurable only if you enable the Prefix Range option in the Prefix Filters panel.

The Local Preference parameter is configurable only if you enable the Local Preference option in the Prefix Filters panel.

The Min. Health Indicator %, Max. Health Indicator % , Duration, and Duration Unit parameters are configurable only if you enable the Health Indicator option in the Prefix Filters panel, and if the Local Preference, MED, Path Length, and Route Target options are disabled. The Health Indicator option can be enabled for IPv4, VPN IPv4, IPv6, and VPN IPv6 BGP prefixes.

The Originating AS parameter is configurable only if you enable the Originating AS option in the Prefix Filters panel.

The Prefix Type parameter is configurable only if you enable the Prefix Type option in the Prefix Filters panel.

The Next Hop parameter is configurable only if you enable the Next Hop option in the Prefix Filters panel.

The Route Distinguisher Type and Route Distinguisher parameters are configurable only if you enable the Route Distinguisher option in the Prefix Filters panel.

The MED parameter is configurable only if you enable the MED option in the Prefix Filters panel.

The AS Path Length parameter is configurable only if you enable the Path Length option in the Prefix Filters panel.

The Type and Route Target parameters are configurable only if you enable the Route Target option in the Prefix Filters panel.

Note: The Health Indicator option identifies the percentage of time that a prefix has been seen by the BGP for the last few days. The health indicator identifies how stable a prefix is. The health indicator is configured as a percentage from 0% to 100%, for a number of days, from 1 to 7. For example, if you set the health indicator to 90% for the last 3 days, all of the prefixes that have been available for at least 90% of the time during last 3 days are retrieved. When you select only the Health Indicator option, the retrieved prefix list does not contain any route attributes, such as Next Hop or MED.

The CPAA keeps track of all of the VPN IPv4 MP-BGP prefixes for up to 7 days, and calculates how long the prefix has been available. The prefix availability time is aggregated and stored every hour for 24 hours and every day for 7 days. When the BGP is activated on the CPAA, it starts its internal hourly and daily timer to aggregate the prefix availability time. For instance, if BGP comes up at 3:25 AM on the CPAA clock, the CPAA performs the aggregation every hour at the 25 minutes past the hour and every day at 3:25 AM. The CPAA keeps the results of last 24 hourly and 7 daily aggregations. If a user at 10 AM tries to retrieve all of the prefixes that have been available for last day, the prefixes that have a health indicator of 100% for the last 6 hours and 35 minutes—the time since 3:25 AM—are retrieved. To prevent confusion on the BGP Prefix Info tab of the Retrieved BGP Prefixes (Edit) form, the exact duration for the health indicator calculation, (6 hours and 30 minutes in this example), and the start of the 24 hours aggregation period, (3:25 AM in this example), are reported.

The CPAM displays the status of the prefix—present or deleted—for the retrieved prefix health on the BGP Prefix Info tab for the retrieved prefixes. For absent prefixes, the down time since the deletion is displayed.


Perform the following if you enabled the Community Strings option in the Prefix Filters panel:

  1. Click on the Communities tab and click Add.

  2. Configure the Value parameter and click OK.


Save your changes and close the BGP Prefix List Filter form.

End of steps

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