Nonstop Active Routing PIM Support

Nonstop active routing supports Protocol Independent Multicast (PIM) with stateful replication on backup Routing Engines. State information replicated on the backup Routing Engine includes information about neighbor relationships, join and prune events, rendezvous point (RP) sets, synchronization between routes and next hops, and the forwarding state between the two Routing Engines.

To configure nonstop active routing for PIM, include the same statements in the configuration as for other protocols: the nonstop-routing statement at the [edit routing-options] hierarchy level and the graceful-restart statement at the [edit chassis redundancy] hierarchy level. To trace PIM nonstop active routing events, include the flag nsr-synchronization statement at the [edit protocols pim traceoptions] hierarchy level.

Note: The clear pim join, clear pim register, and clear pim statistics operational mode commands are not supported on the backup Routing Engine when nonstop active routing is enabled.

Nonstop active routing support varies for different PIM features. The features fall into the following three categories: supported features, unsupported features, and incompatible features.

Supported features:

• Auto-RP
• BFD
• Bootstrap router
• Dense mode
• Sparse mode (except for some subordinate features mentioned in the following list of unsupported features)
• Source-specific multicast (SSM)
• Static RPs

Unsupported features: You can configure the following PIM features on a router along with nonstop active routing, but they function as if nonstop active routing is not enabled. In other words, during Routing Engine switchover and other outages, their state information is not preserved and traffic loss is to be expected.

• Internet Group Management Protocol (IGMP) exclude mode
• IGMP snooping
• PIM for IPv6 and related features such as embedded RP and Multicast Listener Discovery (MLD)
• Policy features such as neighbor policy, bootstrap router export and import policies, scope policy, flow maps, and reverse path forwarding (RPF) check policies.
• Upstream assert synchronization

Incompatible features: Nonstop active routing does not support the following features, and you cannot configure them on a router enabled for PIM nonstop active routing. The commit operation fails if the configuration includes both nonstop active routing and one or more of these features:

• Anycast RP
• Draft-Rosen multicast VPNs (MVPNs)
• Local RP
• Next-generation MVPNs with PIM provider tunnels
• PIM join load balancing

JUNOS software provides a configuration statement that disables nonstop active routing for PIM only, so that you can activate incompatible PIM features and continue to use nonstop active routing for the other protocols on the router. Before activating an incompatible PIM feature, include the nonstop-routing disable statement at the [edit protocols pim] hierarchy level. Note that in this case nonstop active routing is disabled for all PIM features, not only incompatible features.

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