process-non-null-as-null-register

Syntax

Hierarchy Level

Description

When process-non-null-as-null-register is enabled on a PTX device serving as PIM Rendezvous Point (RP) for multicast traffic, it allows the device to treat non-null registers, such as may be sent from any first hop router (FHR), as null registers, and thus to form a register state with the device. This statement is required when RP is enabled on PTX devices running Junos OS Evolved.

More Information

In typical operation, for PIM any-source multicast (ASM), all *,G PIM joins travel hop-by-hop towards the RP, where they ultimately end. When the FHR receives its first traffic, it forms a register state with the RP in the network for the corresponding S,G. It does this by sending a PIM non-null register to form a multicast route with the downstream encapsulation interface. The RP decapsulates the non-null register and forms a multicast route with the upstream decapsulation device. In this way, multicast data traffic flows across the encapsulation/decapsulation tunnel interface, from the FHR to the RP, to all the downstream receivers until the RP has formed the S,G multicast tree in the direction of the source.

Without process-non-null-as-null-register enabled, for PIM ASM, PTX devices can only act as a PIM transit router or last hop router. These devices can receive a PIM join from downstream interfaces and propagate the joins towards the RP, or they can receive an IGMP/MLD join and propagate it towards a PIM RP, but they cannot act as a PIM RP itself. Nor can they form a register state machine with the PIM FHR in the network.

Required Privilege Level

routing—To view this statement in the configuration.

routing-control—To add this statement to the configuration.

Release Information

Statement introduced in Junos OS Evolved Release 19.3R1.