Understanding PIM Register Messages

When a source in a multicast network becomes active, the source’s designated router (DR) encapsulates multicast data packets into a PIM register message and sends them by means of unicast to the rendezvous point (RP) router.

To prevent unauthorized groups and sources from registering with an RP router, you can define a routing policy to reject PIM register messages from specific groups and sources and configure the policy on the designated router or the RP router.

• If you configure the reject policy on an RP router, it rejects incoming PIM register messages from the specified groups and sources. The RP router also sends a register stop message by means of unicast to the designated router. On receiving the register stop message, the designated router sends periodic null register messages for the specified groups and sources to the RP router.
• If you configure the reject policy on a designated router, it stops sending PIM register messages for the specified groups and sources to the RP router.

Note: If you have configured the reject policy on an RP router, we recommend that you configure the same policy on all the RP routers in your multicast network.

Note: If you delete a group and source address from the reject policy configured on an RP router and commit the configuration, the RP router will register the group and source only when the designated router sends a null register message.

Related Topics

• Junos OS Feature Support Reference for SRX Series and J Series Devices
• Multicast Overview
• Example: Rejecting Incoming PIM Register Messages on an RP Router (CLI)
• Example: Stopping Outgoing PIM Register Messages on a Designated Router (CLI)
• Filtering Multicast Messages in the Junos Multicast Protocols Configuration Guide
• Routing Policies Overview