Protocol Independent Multicast (PIM) nonstop active routing (NSR) for Virtual Extensible LANs (VXLANs)

The Layer 2 address learning daemon (l2ald) passes VXLAN parameters (VXLAN multicast group addresses and the source interface for a VXLAN tunnel vtep-source-interface to the routing protocol process on the primary Routing Engine. The routing protocol process forms PIM joins with the multicast routes through the pseudo-VXLAN interface based on these configuration details. Because the l2ald daemon does not run on the backup Routing Engine, the configured parameters are not available to the routing protocol process in the backup Routing Engine when NSR is enabled. The PIM NSR mirroring mechanism provides the VXLAN configuration details to the backup Routing Engine, which enables creation of the required states. The routing protocol process matches the multicast routes on the backup Routing Engine with PIM states, which maintains the multicast routes in the Forwarding state.