Configure PIM Bidirectional Neighbor Filters

A PIM bidirectional neighbor filter is an ACL that defines the neighbor devices that can participate in the Designated Forwarder (DF) election. If a PIM bidirectional neighbor filter is not configured for an interface, there are no restrictions. If a PIM bidirectional neighbor filter is configured, only those neighbors permitted by the ACL can participate in the DF election process.

Bidirectional PIM allows multicast routers to keep reduced state information. All of the multicast routers in a segment must be bidirectionally enabled to elect a DF.

When a PIM bidirectional neighbor filter is enabled, the routers that are permitted by the ACL are considered to be bidirectionally capable. Therefore, the following is true:

  • If a permitted neighbor does not support bidirectional mode, then the DF election does not occur.

  • If a denied neighbor supports bidirectional mode, then the DF election does not occur.

  • If a denied neighbor does not support bidirectional mode, the DF election can occur.

Procedure

Step 1

Choose Devices > Device Management, and edit the threat defense device.

Step 2

Choose Multicast Routing > PIM.

Step 3

On Bidirectional Neighbor Filter, click Add or Edit.

Use the Add PIM Bidirectional Neighbor Filter dialog box to create ACL entries for the PIM bidirectional neighbor filter ACL. Use the Edit PIM Bidirectional Neighbor Filter dialog box to change existing parameters.

Step 4

Configure the following options:

  • From the Interface drop-down list, select the interface to which you want to configure the PIM bidirectional neighbor filter ACL entry.

  • Standard Access List— From the Standard Access List drop-down list, select a standard ACL or click Add (add icon) to create a new standard ACL. See Configure Standard ACL Objects for the procedure.

    Note

    Choosing Allow on the Add Standard Access List Entry dialog box lets the specified devices participate in the DR election process. Choosing Block prevents the specified devices from participating in the DR election process.

Step 5

Click OK to save the PIM bidirectional neighbor filter configuration.