which BGP process can be distributed into multiple instances?

Another BGP optimization option that is available on Cisco IOS XR Software platforms is process restartability. Critical control-plane processes (such as the BGP routing process) can be both manually and automatically restarted in response to a process failure, as opposed to restarting the entire operating system.

You can manually restart the BGP process by entering the admin mode and using the process restart command, followed by the job ID of the BGP process. You can determine the BGP process ID using the show processes bgp command.

Distributed BGP splits BGP functionality into three process types with several instances:
– BGP process manager (one instance)
– brIB process (one instance per address family)
– BGP speaker process (up to 15 instances)

Distributed BGP is used to reduce the impact that a fault in one address family has on another
address family.

Distributed BGP also allows more CPU capacity for receiving, computing, and sending BGP
routing updates. When in distributed BGP mode, you can control the number of distributed
speakers that are enabled, as well as which neighbors are assigned to each speaker.

Instruct the router to clear the current BGP mode and switch to distributed, using the clear bgp current-mode command.