Multicast Non-Stop Routing
Multicast non-stop routing (NSR) provides hitless-failover support on all platforms
for IPv4 multicast features (default and non-default VRFs): PIM-DM, PIM-SM, and PIM-SSM.
By default, multicast NSR is enabled. The software state is kept in sync between the active and standby modules. The standby module is NSR ready when the software state of the standby and active modules are in sync. When the standby module is NSR ready, a hitless-failover does not result in a disruption to the multicast forwarding state or traffic
The following message is displayed on the console of the active and standby modules to indicate that the standby module is NSR ready:
Mcastv4 is NSR ready
Unicast routing must be protected by NSR or graceful restart on all multicast virtual routing and forwarding (VRF).