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Configuring PIM Designated Router Election on Point-to-Point Links

 

In PIM sparse mode, enable designated router (DR) election on all PIM interfaces, including point-to-point (P2P) interfaces. (DR election is enabled by default on all other interfaces.) One of the two routers might join a multicast group on its P2P link interface. The DR on that link is responsible for initiating the relevant join messages. (DR priority is specific to PIM sparse mode; as per RFC 3973, PIM DR priority cannot be configured explicitly in PIM Dense Mode (PIM-DM) in IGMPv2 – PIM-DM only support DRs with IGMPv1.)

To enable DR election on point-to-point interfaces:

  1. On both point-to-point link routers, configure the router globally or in the routing instance. This example shows the configuration for the routing instance.
  2. Verify the configuration by checking the State field in the output of the show pim interfaces command. The possible values for the State field are DR, NotDR, and P2P. When a point-to-point link interface is elected to be the DR, the interface state becomes DR instead of P2P.
  3. If the show pim interfaces command continues to report the P2P state, consider running the restart routing command on both routers on the point-to-point link. Then recheck the state.Caution

    Do not restart a software process unless specifically asked to do so by your Juniper Networks customer support representative. Restarting a software process during normal operation of a routing platform could cause interruption of packet forwarding and loss of data.

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