Non-Stop Forwarding (NSF): The ability of the forwarding plane to continue running “headless” if the control plane stops. NSF allows you to switch from a primary to a backup control plane without disrupting forwarding.

The objective of NSR is to prevent, or at least minimize, the effect of broken peering sessions. A  newer generation of NSR uses internal processes to keep the backup control plane aware of routing protocol state and adjacency maintenance activities, so that after a switchover the backup control plane can take charge of the existing peering sessions rather than having to establish new ones. NSR process is internal (and vendor specific) there is no need for the neighbors to support any kind of protocol extension.

Graceful Restart (GR) protocol extensions.