Netbackup communication process between client and servers.

Bpcd is the connection daemon on clients (and servers). When a media server wants to initiate a backup job for a client it will do this via bpcd (connection will usually goto pbx first before bpcd or sometimes vnetd if pbx is not available) Bpcd will then check if that server is allowed to request that backup or restore by checking incoming ip of the media server resolves to a hostname in the clients SERVER list. Bpcd is then responsible for launching the client process such as bpbkar or tar for backups and restores depending on the incoming request (usually from bpbrm on the media server)